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Water Supply & Distribution — Plumber Practice Questions

103 questions · 18% of the Plumber exam

Worked questions

1. Installing a pressure-reducing valve with an integral check on the water service turned the building piping into a closed system. To satisfy the code, what must be provided on the water heater side of that system?

  • AAn additional hose bibb near the heater to bleed pressure

    Bleeding pressure by hand at a hose bibb is not an approved control. The pressure rise happens every heating cycle, day and night, whether anyone is there to open a valve or not.

  • BA relief valve with a higher pressure rating

    The relief valve rating is matched to the heater and must not be raised. Uprating it removes the last safety device rather than solving the pressure rise that is lifting it.

  • CA check valve on the hot water outlet of the heater

    A check valve on the hot outlet makes the problem worse by trapping the heated volume even more tightly. It adds another barrier instead of providing relief.

  • An approved device or tank to control thermal expansion

Why D is correct

A closed system must be given somewhere for the expanding heated water to go. An approved expansion tank or equivalent device absorbs the volume increase so system pressure stays within the safe range and the relief valve is not used as a pressure regulator.

What this question is testing

Checks that the candidate can recognize when a system has been made closed, understands why heating then raises pressure, and knows that the code demands an engineered control rather than tolerating relief valve discharge.

On the job

This is one of the most common service calls in the trade. A regulator or a new backflow preventer goes in, and within days the water heater relief valve starts weeping onto the pan. Plumbers who do not understand the mechanism replace the relief valve, then replace it again. The real fix is an expansion tank charged to match the static pressure setting, mounted on the cold inlet with support so its weight does not hang on the piping.

Memory technique

Close the system and heated water has nowhere to grow; give it a tank.

Exam tip

Any question that mentions a regulator, check valve or backflow preventer plus a water heater is pointing at thermal expansion.

Where to look it up

IPC Chapter 6, hot water supply and distribution, thermal expansion control. UPC addresses closed system expansion in its water heater chapter instead, so check the code your state adopted.

2. A water service pipe and a building sewer are being installed on the same lot. What does the code require regarding their separation in the ground?

  • AThey must be separated by at least 2 feet measured vertically, with the water service placed on top and no horizontal separation required at all

    A vertical dimension does appear inside one of the code's alternatives, along with a shelf and specific material conditions, so the shape of the answer is familiar. The figure there is 12 inches, and it is not a stand-alone rule.

  • BThey may share a trench without restriction provided both lines are plastic piping with gasketed joints throughout

    Material is part of one of the alternatives, which is where this comes from. That alternative requires the sewer to be built of approved pressure rated material with suitable joints, not simply any plastic pipe.

  • CThey must be at least 10 feet apart horizontally under all conditions, measured from the outside of one pipe to the other

    Ten feet is a genuine separation figure, used between a water well and a septic system. Carrying it into this question swaps a source protection rule for the trench separation rule that actually governs here.

  • They must be separated by 5 feet of undisturbed or compacted earth, unless one of the alternative arrangements the code permits is used

Why D is correct

Five feet of undisturbed or compacted earth is the baseline separation, with named alternatives that allow a shared trench under controlled conditions. The alternatives are conditional, so they must be met exactly rather than approximated.

What this question is testing

Checks whether the candidate knows the baseline separation and, just as importantly, that the code contains conditional alternatives rather than a flat prohibition on shared trenches.

On the job

The excavator will always ask for one trench, and there is a compliant way to give it to him, but it has to be planned. Get the sewer material and the shelf detail approved before the machine shows up. Also confirm the local water purveyor has no stricter rule, because utilities frequently impose their own separation requirements that exceed the plumbing code on their side of the meter.

Memory technique

Five feet of dirt, or meet the exception exactly.

Exam tip

When a rule has exceptions, the exam usually tests whether you know the exceptions exist.

Where to look it up

IPC Chapter 6, water service pipe, separation from the building sewer. UPC uses a different arrangement based on vertical and horizontal offsets, so this is a genuine code-to-code difference; follow the code your state adopted.

3. You are making up a combination relief valve on a new 50-gallon tank. Where does the code require the temperature-sensing element of that valve to end up once the valve is installed?

  • Within the top 6 inches of the tank, in contact with the hottest water in the vessel.
  • BInside the cold water dip tube, so that incoming water passes across the element.

    The dip tube carries incoming cold water. An element there would read cold while the top of the tank boils.

  • CIn the discharge piping just downstream of the valve body, so the element stays dry until relief occurs.

    An element in the discharge line senses nothing until water is already flowing past it, which is far too late.

  • DAt the midpoint of the tank shell, where the average stored temperature can be sensed.

    Mid-tank readings lag the hottest layer, so the valve would open only after the top of the vessel is already dangerously hot.

Why A is correct

A runaway water heater overheats from the top down, so a valve that senses the top 6 inches of stored water sees the hazard first. That is why the code fixes the element location rather than leaving it to the installer.

What this question is testing

Whether the candidate knows the installed geometry that makes a T and P valve work, not just that one is required.

On the job

Field crews sometimes install a pressure-only relief valve on a side tapping, or extend a T and P valve out on a long nipple so the probe never reaches the water. Both defeat the temperature function entirely. When you replace a relief valve, check the probe length against the tapping so the element ends up in the water, and never plug a factory T and P tapping to move the valve somewhere more convenient.

Memory technique

Heat floats, so the probe sits in the attic of the tank.

Exam tip

The T and P element belongs in the top of the tank; anything that keeps it out of the hottest water is wrong.

Where to look it up

IPC Section 504 covers water heater safety devices, including relief valve requirements and installation. UPC states similar requirements in its water heater chapter under different section numbers.

4. A gravity storage tank will supply the top floor of a building. The highest fixture outlet served needs 20 pounds per square inch of flowing pressure. Take these values as given: friction loss between the tank and that outlet is 5 pounds per square inch at design flow, and each foot of elevation is worth 0.433 pound per square inch. How far above that outlet must the water level in the tank stand?

  • AAbout 46 feet.

    This covers the fixture requirement but drops the 5 pounds of friction loss, so the far outlet would fall short at design flow.

  • About 58 feet.
  • CAbout 25 feet.

    This treats 1 pound per square inch as 1 foot of water, which understates the required height by more than half.

  • DAbout 11 feet.

    This multiplies by 0.433 instead of dividing by it, the most common direction error in head conversions.

Why B is correct

Head has to cover both the fixture requirement and the friction between tank and fixture, and converting psi to feet means dividing by 0.433, which is the same as multiplying by 2.31 feet per pound.

What this question is testing

Whether the candidate can convert a pressure requirement into elevation in the correct direction and include friction in the requirement.

On the job

Gravity tanks still serve the upper floors of older mid-rise buildings, and the top floor is always the one that complains. When a renovation adds a shower or a flushometer up there, run this check before promising performance, and remember the usable head shrinks as the tank drains, so design from the low water level rather than the overflow.

Memory technique

Every 2.31 feet of standing water buys you 1 pound.

Exam tip

Feet to pounds, multiply by 0.433. Pounds to feet, divide by 0.433 or multiply by 2.31.

Where to look it up

Gravity tank and booster provisions are in IPC Chapter 6, and design pressure criteria are in Section 604. UPC covers gravity tanks separately, so verify the details against your adopted code.

5. A frost-proof hose bibb is being roughed in on the exterior wall of a commercial building. Under the IPC table of minimum fixture supply pipe sizes, what is the smallest nominal supply permitted to serve that hose connection?

  • A3/8 inch nominal

    Three eighths is the table minimum for low-flow connections such as a flush tank. A hose connection carries several times that demand.

  • 1/2 inch nominal
  • C3/4 inch nominal

    Three quarters is a sensible size for a long run or for a wall hydrant serving a wash-down, but the table does not require it as the minimum.

  • D1 inch nominal

    One inch is the minimum listed for a flushometer valve water closet, not for a hose connection. Carrying that number across rows overstates the requirement.

Why B is correct

A hose bibb is expected to supply a garden hose at a usable rate, so the table assigns it a half inch nominal minimum. Anything smaller would throttle the outlet before the hose ever got a chance to.

What this question is testing

Whether the candidate can locate the minimum fixture supply table and read the hose connection row without confusing it with adjacent fixture rows.

On the job

On commercial work the practical question is not the code minimum but the length of the run: a half inch line feeding a hose bibb sixty feet from the riser will disappoint anyone trying to fill a mop bucket. Contractors routinely run three quarter inch to hose bibbs and wall hydrants for that reason. Knowing the code floor tells you when an existing half inch stub can stay and when the complaint you were called about is a sizing problem rather than a code violation.

Memory technique

Half inch feeds the hose, an inch feeds the flushometer.

Exam tip

Memorize the shape of the fixture supply table rather than every number: small for tank fills, half inch for most fixtures, an inch for flushometers.

Where to look it up

IPC Chapter 6, Table 604.5, minimum sizes of fixture water supply pipes. The UPC publishes its own fixture supply table, so verify the entry in your adopted code.

6. A building's fixtures total 180 water supply fixture units. Of that total, 120 units belong to flushometer valve water closets and urinals and the remaining 60 units belong to lavatories, sinks and flush tank fixtures. Take these conversions as given data: on the predominantly flush tank curve 60 units equals 26 gallons per minute and 180 units equals 52 gallons per minute; on the predominantly flush valve curve 120 units equals 65 gallons per minute and 180 units equals 82 gallons per minute. The design procedure on this project directs that a system containing flushometer valve fixtures be converted on the flush valve curve using the total of all fixture units in the system. What design flow sizes the service?

  • AA design flow of 52 gallons per minute

    This reads the full 180 units on the flush tank curve. The flush tank curve assumes no fixture dumps 25 gallons per minute in a ten second burst, which is exactly what a flushometer valve does, so it undersizes the service badly.

  • BA design flow of 65 gallons per minute

    This converts only the flushometer valve fixtures and forgets the lavatories, sinks and tank fixtures that share the same pipe. Every fixture connected downstream of the section being sized has to be in the total, whatever its type.

  • CA design flow of 91 gallons per minute

    This converts each group on its own curve and adds the two demands, 65 plus 26. Each curve already contains a diversity allowance, so adding two curve readings applies that allowance twice and produces a flow the building will never see.

  • A design flow of 82 gallons per minute

Why D is correct

One curve is entered one time with one number. The flushometer valve fixtures force the flush valve curve, and the total load on the pipe being sized is all 180 fixture units, so the reading is 82 gallons per minute. Converting the two groups on two curves and adding them double counts the diversity that each curve already contains.

What this question is testing

This checks whether you can decide which demand curve a system belongs to and what total belongs in it, which is the first decision in every water sizing problem and the one that costs the most when it goes wrong. It also checks whether you understand that a demand curve is not additive.

On the job

Mixed systems are the normal case in commercial work: a shopping center with tank type closets in the tenant spaces and a flushometer valve restroom in the anchor. The estimator who converts the two halves separately and adds them ends up buying a service one size larger than the job needs, and the plumber who reads the whole thing on the tank curve ends up with flushometer valves that will not complete their cycle when two fire at once.

Memory technique

One pipe, one curve, one total: never add two curve readings together.

Exam tip

If any flushometer valve fixture is on the system, the flush valve curve governs and the whole fixture unit total goes into it once.

Where to look it up

Water sizing procedure and the demand curves live in IPC Appendix E, with the load values in the fixture unit table there. UPC states size water piping from their own fixture unit table and their own sizing appendix, and the numbers are not the same, so confirm against the code your state adopted.

7. A branch carries 55 water supply fixture units. The demand table published for this project lists 50 units at 24 gallons per minute and 60 units at 27 gallons per minute, with no row in between. The design procedure for this project directs that where a fixture unit total falls between published rows, the next higher row is used. What demand sizes the branch?

  • AA design demand of 24 gallons per minute

    This takes the lower row, 50 units at 24 gallons per minute, which credits the branch with less demand than the 55 units connected to it actually produce. Every rounding rule in pipe sizing points toward more capacity, not less.

  • A design demand of 27 gallons per minute
  • CA design demand of 25.5 gallons per minute

    This interpolates halfway between the two rows. The demand curve behind the table is not a straight line, so interpolation is not exact, and the procedure for this project directs the next higher row instead.

  • DA design demand of 55 gallons per minute

    This treats fixture units as though they were gallons per minute. A fixture unit is an index of probable simultaneous use, not a flow rate, and the two are only connected through the conversion table.

Why B is correct

Fifty-five units sits between the two published rows, and the procedure directs that the next higher row be used, so the branch is sized on 27 gallons per minute. Rounding upward keeps the pipe on the safe side of a curve that flattens as fixture counts rise, which is the reason the rule points that way rather than toward the nearer row.

What this question is testing

This checks whether you round in the safe direction when a fixture unit total falls between table rows, and whether you can keep fixture units and gallons per minute apart in your head.

On the job

Every published demand table has gaps, and every jurisdiction has a habit about how to close them. Some accept interpolation, most expect the next higher line, and a plan reviewer who is used to seeing round numbers will stop on a value that could only have come from interpolation. Writing the row you used next to the number on the calculation sheet saves an argument.

Memory technique

Between two lines, step up: a fixture unit is never a gallon.

Exam tip

When a total lands between rows, take the higher one, and never read a fixture unit total as a flow.

Where to look it up

The demand conversion table is in IPC Appendix E; check whether your jurisdiction publishes an interpolation policy. UPC states size water piping from their own fixture unit table and their own sizing appendix, and the numbers are not the same, so confirm against the code your state adopted.

8. A tall building is zoned so that static pressure at the lowest fixture in each zone stays within the 80 pound per square inch ceiling the code places on the water distribution system. The pressure-reducing valve at the top of a zone is set to deliver 62 pounds per square inch. Using 0.433 pound per square inch for each foot of elevation, given, what is the greatest height that zone may extend below the valve?

  • AAbout 18 feet

    This is the pressure difference itself, 18 pounds per square inch, read as though it were a height in feet. Pressure and head are related by 0.433 pound per square inch per foot, so the two numbers are never interchangeable.

  • BAbout 143 feet

    This converts the valve setting itself to a height rather than the difference between the setting and the ceiling. The 62 pounds per square inch is already present at the top of the zone and none of it is available to be spent on falling.

  • CAbout 185 feet

    This converts the entire 80 pound per square inch ceiling to height and ignores the pressure the valve is already delivering at the top of the zone. It would put the lowest fixture at well over twice the permitted static pressure.

  • About 41 feet

Why D is correct

Only the difference between the ceiling and the valve setting is available to be spent on elevation: 80 minus 62 equals 18 pounds per square inch, and 18 divided by 0.433 gives about 41 feet of drop. Below that the static pressure at the lowest fixture passes the limit and a second pressure zone is required.

What this question is testing

This checks whether you can work between pressure and elevation head in the correct direction, and whether you recognize that only the margin between the valve setting and the code ceiling is available to spend on height.

On the job

Zoning a high-rise is this calculation repeated up the building, and the setting chosen for each valve trades zone height against the flow pressure the top floor of that zone receives. Set the valve high and the zone gets short and the valve stations multiply; set it low and the top floor showers disappoint. Field crews meet the same arithmetic in reverse when a homeowner in a hillside subdivision reports leaking fixtures on the lowest floor.

Memory technique

Headroom in pounds, divided by 0.433, becomes headroom in feet.

Exam tip

Subtract the setting from the ceiling first, then convert. Converting first is the trap.

Where to look it up

The 80 pound per square inch limit and the requirement for a pressure-reducing valve are in IPC 604.8. UPC states carry a comparable limit in their own water distribution chapter under different numbering.

95 more in the bank

Answers and explanations for these are in the app.

  • Potable water travels from the utility main to the point where the interior piping of the building begins. Under the code, what is the correct classification for that buried run of pipe?
  • A water service pipe must be sized for the demand of the structure it feeds, but the code also sets an absolute floor on its diameter. What is that minimum nominal size for a water service pipe?
  • You measure static pressure at the building of 96 psi with no water flowing. The code limits the static pressure delivered to the building water distribution system. What corrective work does the code require here?
  • The code requires devices that absorb the shock wave created when flowing water is stopped abruptly. Under what condition does the code call for water hammer arrestors to be installed?
  • The available street pressure is not enough to deliver the required flow and pressure at the highest and most remote fixture outlet. What does the code require the designer to provide?
  • The fixtures in a small office total 60 water supply fixture units. The conversion table given for this problem shows that 60 water supply fixture units of predominantly flush-tank demand equals 26 gallons per minute. The same service must also carry a continuous irrigation demand of 5 gallons per minute. What total design flow should be used to size the water service?
  • A cold water riser serves five identical apartments stacked one above another. Each apartment contains fixtures totaling 9 water supply fixture units. For this problem, use the given conversion values: 9 water supply fixture units equals 8 gallons per minute, and 45 water supply fixture units equals 24 gallons per minute. What design flow governs the riser section below the lowest apartment?
  • Static pressure at the meter measures 62 psi. The highest fixture outlet is 38 feet above the meter. Use 0.433 psi for each foot of elevation. Friction loss through the meter, the piping and the fittings totals 14 psi at the design flow. What pressure remains available at that highest outlet while water is flowing?
  • A regulator on the service is set to deliver 75 psi to the lower zone. The most remote fixture in that zone requires 20 psi flowing at its outlet, and friction loss to that fixture totals 12 psi. Using 0.433 psi per foot of elevation, what is the greatest height above the regulator that this zone can serve?
  • You are preparing to disinfect a newly installed section of water distribution piping consisting of 240 feet of 2-inch pipe. For this problem, use the given value that 2-inch pipe holds 0.163 gallon per foot. How much water does the section contain?
  • A newly installed copper water distribution system must be tested and proved tight before it is concealed. Which test method does the code accept for this piping?
  • A new potable water distribution system must be purged and disinfected before it is placed in service. Which chlorination procedure does the code accept?
  • An air gap is being used to protect a potable water outlet discharging above a receptor. How does the code establish the minimum vertical distance for that air gap?
  • An atmospheric vacuum breaker has been selected to protect a fixture supply against back-siphonage. Which installation condition does the code require for this device to be acceptable?
  • An underground irrigation system has electrically operated zone valves downstream of the point of connection, and the supply to it stays pressurized all season. Which backflow device suits this arrangement?
  • A potable make-up line feeds a boiler whose water is chemically treated, and the connection remains under pressure with the possibility of backpressure from the boiler. What protection does this high hazard connection require?
  • A threaded hose connection on the exterior of a building must be protected against backflow because a hose end can end up submerged. What does the code require at that outlet?
  • Cross-connection control requires that potable water never be exposed to a path back from a nonpotable source. Which of the following installations is a prohibited cross connection?
  • A wet-pipe fire sprinkler system contains no antifreeze or chemical additive and has no auxiliary water supply, so its connection is classified as a low hazard under continuous pressure. What is the minimum backflow protection the code accepts for it?
  • The code requires a shutoff valve so that a storage water heater can be isolated for service without shutting down the rest of the building. Where must that valve be installed?
  • The code requires a valve that opens to the full bore of the pipe at a specific point on the incoming water service. Which location does that requirement cover?
  • A multiple dwelling is being piped from a single water service. Besides the valve at the service entrance, what additional shutoff requirement applies to the individual dwellings?
  • A fixture fitting has separate controls for hot and cold water. The code fixes which side each control is served from so that users encounter the same arrangement everywhere. How must the hot water control be arranged?
  • The developed length of hot water piping from the source to the most remote fixture exceeds what the code allows without additional measures. What must be provided so the system complies?
  • Discharge piping is being run from the temperature and pressure relief valve on a storage water heater. Which arrangement satisfies the code?
  • A storage water heater is installed in a location where a tank leak would damage the building, so a pan is required beneath it. What does the code require of the pan drain?
  • A water distribution run measures 140 feet of pipe, and the fittings in that run have a combined equivalent length of 45 feet. The pressure budget leaves 9 psi to be spent on friction loss in this run. What allowable friction loss per 100 feet should be used to select the pipe size?
  • Fixture fittings are limited by the code to a maximum flow rate measured at a stated test pressure. What is the maximum flow rate permitted for a shower head?
  • Shutoff valves serving a group of fixtures are being installed inside a framed soffit that will be finished with gypsum board. What does the plumbing code require regarding those valves?
  • A potable water storage tank is being installed to feed the suction side of a building water pressure booster system. What does the code require of that tank and its fill?
  • A hydropneumatic pressure tank is installed as part of a water pressure booster system. What protective device does the code require on that tank, and how must it be set?
  • An elevated potable water storage tank is provided with an overflow pipe. How does the code require that overflow to be arranged?
  • A hot water circulation system with a pump is installed to maintain temperature in a long distribution run. What does the code require of the pump arrangement itself?
  • Heat traps are provided at the hot water outlet and the cold water inlet of a storage water heater. What do those devices accomplish in the system?
  • The temperature of the water delivered to a bathtub fill valve has to be limited so a user cannot be scalded. How does the code expect that limit to be achieved?
  • A storage water heater is being set in the corner of an attached private garage where a vehicle is parked. What does the code require at that location?
  • A storage water heater is being installed in an attic above a finished ceiling. What does the code require so the appliance can be serviced and replaced?
  • Threaded hose connections throughout a building are being reviewed for backflow protection. Which statement correctly describes where the code requires a hose connection backflow preventer?
  • A chemical dispensing unit injects cleaning concentrate into the water supply serving a service sink, and the connection stays under pressure. What degree of protection does the code require at that connection?
  • A wet-pipe fire sprinkler system serving an unheated warehouse is charged with an antifreeze solution and is supplied from the building potable water piping. What backflow protection does the code require at that supply connection?
  • Testable backflow prevention assemblies have been installed on the water service and on several process connections in a building. What does the code require regarding testing of those assemblies?
  • A building supplied by the public water system also has a private well on the same property. How may the two supplies relate to the building piping under the code?
  • Nonpotable piping on a campus feeds flush valves and irrigation zones. What does the code require at the outlets and operating valves of that system so the water cannot be drawn for the wrong use?
  • A new potable water distribution system has been chlorinated for the required period and then flushed out. What does the code require before that system is placed in service?
  • A gravity flush tank water closet is being trimmed out, and its fill valve discharges into water standing in the tank. What does the code require to protect the potable supply at that submerged inlet?
  • Piping is being made up between a storage water heater and the relief valve that serves it. What does the code permit in that connection?
  • Static pressure at the meter is 68 pounds per square inch. The most remote outlet is a flushometer valve that requires 25 pounds per square inch of flowing pressure and sits 24 feet above the meter. Take these values as given: the meter loses 6 pounds per square inch at design flow, the reduced pressure principle assembly on the service loses 12 pounds per square inch, elevation costs 0.433 pound per square inch per foot, the developed length of pipe is 180 feet, and the fittings in that run add 60 feet of equivalent length. How much pressure remains for friction loss, and what does that work out to per 100 feet?
  • A gauge at the water meter on the ground floor reads 54 pounds per square inch with no water flowing. A hose bibb is located in a basement 11 feet below the meter. Using 0.433 pound per square inch per foot of elevation, what static pressure should be present at that hose bibb?
  • A cold water branch must carry 45 gallons per minute. Take these values as given: the design criterion limits velocity to 8 feet per second, a 1-1/4 inch pipe has an inside cross-sectional area of 0.0104 square foot, a 1-1/2 inch pipe has an inside cross-sectional area of 0.0141 square foot, and 1 cubic foot per second equals 449 gallons per minute. What is the smallest of those sizes that keeps velocity within the limit?
  • An existing cold water branch was sized for a capacity of 18 water supply fixture units, and the fixtures on it today total 12.5 water supply fixture units. Take these values as given: each added lavatory counts as 1 water supply fixture unit and each added flushometer valve water closet counts as 10 water supply fixture units. Which addition can that branch still carry without being resized?
  • A newly installed section of water main holds 480 gallons, and the disinfection procedure calls for a chlorine concentration of 50 parts per million. Take this value as given: 1 gallon of 5 percent sodium hypochlorite added to 1,000 gallons of water produces approximately 50 parts per million. How much hypochlorite does that section require?
  • A hydropneumatic tank has a total volume of 86 gallons. Take these values as given: at the selected cut-in and cut-out settings the usable drawdown is 25 percent of the tank volume, the replacement pump delivers 12 gallons per minute, and the pump manufacturer requires a running time of at least 1 minute per cycle. What is the drawdown, and does the tank meet the running time requirement?
  • A reduced pressure principle backflow preventer is being installed in a mechanical room. What does the code require of the discharge from its relief port?
  • A potable water line is being installed to fill a swimming pool. What protection does the code require on that connection?
  • You measure 78 pounds per square inch of static pressure at a hose bibb early on a Sunday. The water purveyor reports that pressure in the main serving the site ranges from 42 to 80 pounds per square inch through the year. Which value governs the sizing of the water distribution system?
  • A commercial storage water heater is being installed in a jurisdiction where the building code assigns seismic design requirements to the structure. What applies to that appliance?
  • A frost-proof wall hydrant is being installed on an exterior wall in a freezing climate, and its barrel drains each time the hydrant is shut off. How does the code expect backflow protection to be handled on that hydrant?
  • A tank-type water closet is being roughed in, and the fixture supply that runs from the branch to the closet stop is being sized. Under the IPC table of minimum fixture supply pipe sizes, what is the smallest nominal size permitted for that supply?
  • A storage water heater is being installed and the crew is checking the tank fittings before piping it. What does the plumbing code require so the tank can be emptied when it is serviced?
  • A barometric loop is shown on a set of drawings as the means of protecting a potable water connection. Under the IPC, what height must that loop reach and what condition does it guard against?
  • The code calls for a full-open valve at certain points in the water distribution system. Which valve style satisfies that requirement, and why does it qualify?
  • A tenant fit-out is being priced and the hot water branch has to be routed to every fixture that requires it. Under the IPC, which of the following fixtures must be supplied with hot or tempered water?
  • Self-closing metering faucets are being specified for the lavatories in a public restroom. Under the IPC limits on maximum water consumption for fixture fittings, how much water is one of those faucets permitted to deliver?
  • A cold water branch is being sized and the measured pipe run is 118 feet. That run contains six 90-degree elbows, two gate valves and one tee where the flow turns into the branch. Take these equivalent lengths as given data: each elbow counts as 4 feet, each gate valve counts as 1 foot, and the branch tee counts as 8 feet. What total developed length do you carry into the sizing table?
  • Static pressure at the water meter reads 74 pounds per square inch. The most remote fixture outlet sits 32 feet above the meter and requires 20 pounds per square inch of flowing pressure. Take these values as given: the meter drops 6 pounds per square inch at design flow, the backflow assembly drops 9 pounds per square inch, and elevation costs 0.433 pound per square inch for every foot of rise. How much pressure remains to cover friction loss in the pipe and fittings?
  • A tempering valve blends stored water at 140 degrees F with cold water at 55 degrees F to deliver water at 120 degrees F. For every 10 gallons the valve delivers at the blended temperature, how many gallons come from the hot side?
  • A booster pump must add 46 pounds per square inch to the water pressure entering a building, and the manufacturer's pump curve is published in feet of total head. Take 2.31 feet of head per pound per square inch as given data. What head must that pump produce?
  • A potable water line will supply makeup to an open cooling tower whose circulating water is dosed with biocide and a scale inhibitor. Under the IPC, what protects the potable water system at that connection?
  • Public lavatories in a new office building are served from a hot water system stored well above 140 degrees F. Under the plumbing code, what has to be provided so those lavatories deliver tempered water to the user?
  • You are sizing the water distribution system for a mid-size commercial building and the plan reviewer asks what method you used. Which statement describes what the plumbing code will accept?
  • Laboratory faucets in a school are fitted with serrated outlets so rubber tubing can be slipped over them, and the sinks are deep enough that a tubing end can lie in standing water. Under the IPC, what protects the potable water supply at those outlets?
  • A building has a reclaimed water system that flushes its water closets, and the potable system will supply makeup to the reclaimed storage tank whenever the reclaimed supply runs short. Under the plumbing code, how must that makeup connection be made?
  • A kitchen sink faucet is being submitted for a commercial break room. Under the IPC limits on maximum flow rate for fixture fittings, which statement correctly pairs the limit with the pressure at which it is measured?
  • The highest fixture outlet on a proposed fourth floor needs 25 pounds per square inch while flowing, and it sits 42 feet above the meter. Take these figures as given for the design flow: friction in the pipe and fittings accounts for 11 pounds per square inch, the meter accounts for 5, and each foot of rise costs 0.433. What static pressure must the meter see for that outlet to work?
  • An underground lawn irrigation system protected by a pressure vacuum breaker is being modified so that liquid fertilizer is injected into the irrigation piping downstream of the point of connection. Under the IPC, what does that change require at the potable connection?
  • Potable water is going to be heated indirectly by a heat transfer fluid circulating through a heat exchanger. Under the plumbing code, what governs that heat exchanger when the transfer fluid is anything other than potable water?
  • A thermal expansion tank is being added to a building whose water service now carries a check device, making the piping a closed system. Where does that expansion tank belong?
  • A single appliance will supply both the domestic hot water and the space heating water for a small building, with the same water circulating through the heating coils and the fixtures. Under the plumbing code, what governs that arrangement?
  • An emergency shower and eyewash unit is being piped in an industrial building. What does the plumbing code require of the water supply serving that emergency equipment?
  • A cold water branch carries 27 water supply fixture units. Take these capacities as given for the pressure range and developed length of this run: 3/4-inch pipe carries 14 units, 1-inch pipe carries 25 units, 1-1/4-inch pipe carries 44 units and 1-1/2-inch pipe carries 68 units. What is the smallest of those sizes that will serve the branch?
  • Eight identical hotel guest bathrooms are served from one branch. Each contains one flush tank water closet, one lavatory and one bathtub with shower. Take these load values as given data: a flush tank water closet is 2.2 units where the fixture is private and 5 units where it is public; a lavatory is 0.7 private and 2 public; a bathtub with shower is 1.4 private and 4 public. Fixtures in the guest rooms of a hotel are classified as private use. What total load does the branch carry?
  • A cold water branch must deliver 38 gallons per minute, and the pressure budget for that run allows a friction loss of 2.6 pounds per square inch per 100 feet of pipe. The tables available give capacity at two friction rates. At 2 pounds per square inch per 100 feet, 1-1/4-inch pipe carries 26 gallons per minute, 1-1/2-inch carries 42 and 2-inch carries 88. At 4 pounds per square inch per 100 feet, 1-1/4-inch pipe carries 38 gallons per minute and 1-1/2-inch carries 60. Which is the smallest size that stays inside the pressure budget?
  • A water service must carry 30 water supply fixture units, and its total developed length measures 160 feet. The sizing table is published in rows of total developed length with no row between the ones given. Take these capacities as given data: 1-inch pipe carries 38 units in the 100-foot row, 32 units in the 150-foot row and 27 units in the 200-foot row, while 1-1/4-inch pipe carries 55 units in the 200-foot row. What size is required?
  • The water sizing table is entered with total developed length. On this job the meter sits 25 feet outside the building, the run from the meter to the base of the riser measures 60 feet, the riser rises 42 feet, and the piping from the top of the riser to the most remote fixture outlet measures 18 feet. A separate 9-foot branch off the first floor main serves a janitor sink. What developed length is used?
  • Take these load values as given data: a bathroom group containing a flush tank water closet counts as 3.6 water supply fixture units when the whole group is present, while the same fixtures counted one at a time are a water closet at 2.2 units, a lavatory at 0.7 units and a bathtub at 1.4 units. A dwelling contains one complete bathroom group of that kind, plus a kitchen sink at 1.4 units and a clothes washer at 1.4 units. What total load is carried into the demand conversion?
  • A cold water riser serves six floors and picks up 16 water supply fixture units at each floor, with the top floor counted as the sixth. Take these capacities as given data: 1-inch pipe carries 32 units, 1-1/4-inch pipe carries 60 units and 1-1/2-inch pipe carries 96 units. Working from the top down, in which section does the riser first have to increase from 1 inch to 1-1/4 inch?
  • An existing 1-1/4 inch cold water main is rated to carry 44 gallons per minute at the design friction rate for this building. The fixtures on it today total 62 water supply fixture units and produce a demand of 31 gallons per minute. A tenant proposes to add fixtures totaling 24 water supply fixture units. Take these conversions as given data: 24 units equals 17 gallons per minute, and 86 units equals 40 gallons per minute. What is the correct finding?
  • A cold water main runs from the meter to a tee where one leg feeds the cold water fixtures and the other feeds the water heater. The building's fixtures total 96 water supply fixture units, and 88 of those units belong to fixtures supplied with both hot and cold water. Take as given the design rule that a fixture supplied with both hot and cold water is counted at three-quarters of its total value on each of the hot and cold branches. What load sizes the main between the meter and the tee?
  • A building's fixtures total 240 water supply fixture units. The water closets and urinals, which account for 96 of those units, will be flushed from a reclaimed nonpotable system piped independently of the potable distribution. Take these conversions as given data: 96 units equals 42 gallons per minute, 144 units equals 56 gallons per minute, and 240 units equals 78 gallons per minute. What demand sizes the potable water service?
  • A water service must carry 30 water supply fixture units, and the street pressure at the site measures 38 pounds per square inch. The service sizing table is published in three pressure ranges. Take these capacities as given data for the developed length of this run: a 1-inch service carries 21 units in the 30 to 45 pound range, 33 units in the 46 to 60 pound range and 45 units in the range above 60 pounds, while a 1-1/4 inch service carries 42 units in the 30 to 45 pound range. What size is required?
  • A 1-1/2 inch water service is rated to carry 120 water supply fixture units at the developed length and pressure range of this site, given. A common laundry room on that service accounts for 24 water supply fixture units, and each apartment adds 12 water supply fixture units. How many apartments can the existing service carry?
  • A branch serves six public flushometer valve water closets. Take as given the load value from the sizing table, which assigns a public flushometer valve water closet 10 water supply fixture units, and the fact that the table assigns that value by fixture type without reference to the volume of a single flush. The existing valves consume 1.6 gallons per flush and the replacements consume 1.28 gallons per flush. What load must the branch be sized for after the change?
  • A pressure-reducing valve serves the upper zone of a building. A gauge on its outlet reads 60 pounds per square inch with nothing flowing, and the manufacturer publishes a fall-off of 12 pounds per square inch for that valve at the design flow of this zone, meaning the outlet pressure sags by that amount while water is moving. The most remote outlet in the zone sits 18 feet above the valve and friction in the piping and fittings accounts for 9 pounds per square inch at that flow. Using 0.433 pound per square inch per foot of rise, given, what flowing pressure reaches that outlet?
  • A 1-inch branch has a total developed length of 310 feet once fitting allowances are included. At the design flow, the friction chart for that size shows a loss of 3.5 pounds per square inch for every 100 feet of pipe, given. The pressure budget leaves 9 pounds per square inch to be spent on friction in this run. What does the check show?
  • A gauge on the second floor of an apartment building reads 58 pounds per square inch with no water flowing. The floors are 11 feet apart, and the cold water riser runs straight from the second floor to the seventh with no valve, regulator or pump between them. Using 0.433 pound per square inch per foot, given, what will a gauge on the seventh floor read with no water flowing?

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