Your FREE Plumber Flashcards 2026 – 250+ Cards

IAPMO (International Association of Plumbing and Mechanical Officials).

The International Code Council (ICC).

To safeguard public health, safety, and welfare relating to plumbing systems.

No — licensing is state-administered by each state's plumbing board (some delegate to municipalities).

The permit holder or their authorized agent — not the inspector.

Rough-in (before concealment), top-out, and final.

By a water test (a 10-ft head of water) or an air test, held for the required time.

By a water or air pressure test held for the required duration.

Only if the code official approves it as an alternate.

Where adopted, a local amendment governs over the base-code provision it modifies.

Western/some South & Midwest states lean UPC; many Eastern/Midwest/Southeast states use the IPC.

The total measured length of a pipe run along its centerline, including the equivalent length of fittings.

A 45-degree single-line drawing that shows piping in three-dimensional form.

At 45 degrees left or right; vertical pipes stay vertical.

A vertical schematic showing how the supply and DWV piping connect floor to floor.

Counting and listing all fixtures from the plans to determine fixture-unit loads and pipe sizes.

Cleanout.

Floor drain.

The plan shows WHERE fixtures are; the riser/isometric shows HOW they connect vertically.

Pull permits, design plumbing, and supervise journeymen and apprentices — often after a business/law exam.

A journeyman works under a master/contractor; a master can supervise and pull permits.

Installations properly supported, aligned, and protected from freezing and physical damage.

With nail/striker plates to guard against punctures by nails and screws.

The state plumbing board / board of contractors (sometimes a municipality), not IAPMO or ICC.

Yes — many states let you bring the adopted code book and a calculator.

Commonly PSI or Prometric (computer-based, proctored).

To confirm it is watertight and gas-tight before it is concealed and put in service.

A 10-foot head of water above the section being tested (held for the required time).

Centerline length including fitting equivalents, used in the sizing tables.

Technical design guidance (fixture units, sizing methods, venting theory) from plumbing engineers.

Drain–Waste–Vent — the gravity drainage and venting side of a plumbing system.

The lowest horizontal drain inside a building that collects all stacks/branches and conveys them to the building sewer.

The piping from the building drain (about 30 in. outside the wall) to the public sewer or septic.

A vertical line of drain, waste, soil, or vent pipe extending through one or more stories.

A soil pipe carries discharge containing fecal matter; a waste pipe carries liquid waste without fecal matter.

Copper (K/L/M), PEX, and CPVC.

PVC, ABS, and cast iron.

K > L > M (K thickest, M thinnest).

Type K (the thickest wall).

No — PVC is a DWV material; use CPVC or copper/PEX for hot water.

Hot and cold water distribution (it tolerates hot water, unlike PVC).

Cross-linked polyethylene — flexible water-supply tubing, freeze-tolerant, needing fewer fittings.

3 inches, regardless of how few fixture units it carries.

About 3 DFU (a public water closet is about 4).

About 1 DFU.

About 2 DFU each.

1¼ inches.

1½ inches.

So surfaces can be readily cleaned and won't harbor filth or bacteria.

The top edge from which water would first overflow — the reference for measuring an air gap.

A weighted average of no more than 0.25% lead on wetted surfaces (and 0.2% for solder and flux).

NSF/ANSI 61 (health effects) and NSF/ANSI 372 (lead content).

A support (chair carrier) that carries the load of a wall-hung fixture such as a wall-hung water closet.

To prevent the fixture from overflowing onto the floor if the drain is blocked.

The spout outlet is kept above the flood-level rim of the tub (an air gap).

Each compartment contributes to the sink's assigned fixture-unit load per the fixtures table.

It is durable and quiet (deadens drainage noise); available as hub-and-spigot or no-hub.

Water that is safe for human consumption.

A fitting that separates dissimilar metals (e.g., copper to steel) to prevent galvanic corrosion.

Galvanic corrosion accelerates at the joint; a dielectric union or brass nipple prevents it.

Water closets, lavatories, drinking fountains, etc., set by occupancy and occupant load.

The occupancy classification and number of occupants.

It corrodes and scales internally over time, restricting flow; rarely used for new water supply.

Solvent cement (one-step), unlike PVC's primer-plus-cement.

A coupling with a neoprene gasket and stainless band/shield clamping two pipe ends together.

The fitting that connects a water closet to the drain and anchors it to the floor.

A wax (or waxless) ring that forms a gas- and water-tight seal.

To carry their weight at the base and at each floor so joints aren't stressed.

The demand value assigned each fixture; summed to size water-distribution pipe.

An air gap — a physical vertical separation with no parts to fail.

At least twice the supply-pipe diameter, and never less than 1 inch.

Any actual or potential link between the potable water supply and a contamination source.

The undesired reverse flow of contaminants into the potable supply.

Back-siphonage is caused by a vacuum (negative supply pressure); back-pressure is caused by downstream pressure exceeding supply pressure.

Reduced Pressure Zone backflow preventer — two checks plus a relief port; for high-hazard connections; installed above grade.

An atmospheric vacuum breaker (AVB) or pressure vacuum breaker (PVB).

Its relief port discharges water, so it must never be submerged in a pit that could flood.

The banging shock wave when fast-moving water is stopped suddenly by a quick-closing valve.

With a sealed water-hammer arrestor installed near the quick-closing valve.

About 2.31 feet of water column (1 ft of rise ≈ 0.433 psi).

Total WSFU demand is read against the table to pick a pipe size that delivers adequate flow and pressure.

To prevent sagging that stresses joints and disrupts flow.

A hose connection vacuum breaker (admits air to break any vacuum).

High hazard could cause illness/death (needs RPZ or air gap); low hazard is non-health (a double check may suffice).

Two independent check valves in series; used for low-hazard cross-connections.

No — an AVB cannot be under continuous pressure and must sit above the flood-level rim.

To prevent contaminants or pollutants from entering the potable water supply.

An air gap is a physical separation (no moving parts); a backflow preventer is a mechanical device that can fail.

At least a set distance above the flood-level rim of the fixture it protects.

A cross-connection that must be eliminated or protected with a backflow preventer.

Washing-machine and dishwasher solenoid valves.

Adequate pressure at the highest, farthest fixture after friction and elevation losses.

Moderate — roughly 5–8 ft/s — to limit erosion and noise.

Both back-siphonage and back-pressure — it is the most complete protection.

Through an air gap (or high loop) so wastewater can't siphon back into the dishwasher.

Yes — these assemblies require periodic testing by a certified backflow tester (often annually).

The EPA Cross-Connection Control Manual.

The piping from the public main (or well) to the building's water-distribution system.

A valve that lowers high street pressure to a safe level for the building (and creates a closed system).

When static street pressure exceeds about 80 psi.

Backflow into the public main — often by a backflow preventer at the service.

At least twice the supply outlet diameter, never less than 1 inch above the flood-level rim.

It forms a cross-connection that allows back-siphonage of contaminants into the potable supply.

It causes erosion, noise, and water hammer; keep velocity moderate.

An exterior faucet for a garden hose; it requires a vacuum breaker to prevent back-siphonage.

Typically ½ inch.

A check valve stops reverse flow but isn't a tested assembly; a backflow preventer is a listed, testable device.

The mark that must be set above the flood-level rim for the device to work.

Its valve seat sits inside the heated wall so the exterior portion drains and won't freeze.

The water pipe connecting the fixture to its branch; minimum sizes are tabulated (e.g., ⅜ in. lavatory).

Hot and cold systems must not allow contamination; heaters use check valves and proper connections.

¼ inch per foot (about a 2% grade).

⅛ inch per foot (about 1%).

A value the code assigns each fixture for its probable discharge load; summed to size drainage pipe.

To maintain a flow velocity that keeps solids in suspension so they don't settle and clog.

The liquid races ahead and strands the solids, leading to stoppages.

About 2 feet per second.

1⁄16 inch per foot (about ½%).

A capped, accessible fitting that lets a plumber rod or clear a stoppage in the drainage piping.

At the base of stacks, near the building-drain/sewer junction, and at major changes of direction.

It must be extended to remain accessible.

As DFUs increase, the minimum required pipe size increases.

The maximum DFU for that diameter, plus a per-branch-interval limit.

40 × ¼ = 10 inches of total fall.

Increase it to the next larger diameter that can carry the load.

Sanitary carries fixture wastewater; storm carries rainwater. They are kept separate.

A vertical storm pipe that carries rainwater from a roof drain down to the horizontal storm drain.

For the contributing roof area and the local rainfall rate.

Their combined area.

So heavy rain doesn't surcharge (overload) the sanitary sewer.

A length of stack (about one story) within which horizontal branches connect; used in stack sizing.

Typically about 30 inches (762 mm) outside the building wall.

Same nominal size as the pipe up to 4 in.; a 4-in. cleanout is acceptable on larger pipe.

A DFU value is assigned based on the flow rate in gpm (a special rule for continuous-flow connections).

Waste that discharges into a receptor through an air gap rather than connecting directly to the drainage system.

An air gap prevents drainage water from siphoning back into the dishwasher (a cross-connection).

An open fixture that receives indirect waste through an air gap.

A device that prevents sewage from backing up into fixtures below the level of the street sewer.

Where fixtures are below the next upstream manhole cover and could back up during a surcharge.

To pump waste up from fixtures below the gravity drain to the building drain or sewer.

A long-sweep (gentle radius) eases flow direction changes in drainage; short-radius fittings are restricted in some drainage uses.

They obstruct flow or trap solids (e.g., certain double fittings on a single connection).

A drain that receives discharge from one or more fixtures and conveys it to a stack or building drain.

A vertical stack that receives the discharge of water closets or fixtures with fecal matter.

A vertical stack that receives the discharge of fixtures other than water closets.

An older single trap on the building drain; modern codes generally prohibit it (it impedes venting).

Sum all upstream DFUs, pick the slope, then read the minimum diameter from the table.

It keeps a self-scouring velocity while leaving cross-section for air movement.

The standard, code-approved fixture trap; its outlet turns horizontally into a vented drain, so it holds its 2–4 in. water seal.

Its outlet turns straight down into the drain, so it self-siphons and pulls its own seal out.

Between 2 and 4 inches (deeper only for special deep-seal traps).

To admit air so flowing waste can't create pressure swings that siphon or blow out trap seals.

A drain pipe that also serves as the vent for one or more fixtures, common in a bathroom group.

A battery of up to eight fixtures, with the vent taken off ahead of the last fixture.

Air Admittance Valve — a one-way mechanical vent; IPC allows it broadly, UPC restricts it.

A device that adds water to a trap (e.g., a floor-drain trap) to keep its seal from evaporating.

Because it is used infrequently, its seal would evaporate and let sewer gas in without one.

To admit air to the drainage system and protect trap seals from siphonage and back-pressure.

One vent serving two fixtures connected at the same level (e.g., back-to-back lavatories).

The dry extension of a soil or waste stack above the highest branch connected to it.

A separate vertical vent pipe supplying air to the drainage system independent of waste flow.

A supplemental vent that adds air to a circuit-vented branch under heavy load.

At least half the diameter of the drain it serves, and never less than 1¼ inches.

2 inches (half the drain diameter).

When its developed length exceeds 40 ft (IPC) — increase one nominal size for the whole length.

To equalize air pressure between the drainage stack and the vent stack and protect trap seals.

The distance from the trap weir to the vent, to protect the trap seal from siphonage.

The fall across the trap arm must not exceed one pipe diameter, or the vent drops below the trap weir.

Self-siphonage, induced (momentum) siphonage, back-pressure, and evaporation.

S-traps, bell traps, drum traps (except special uses), crown-vented, and mechanical-seal traps.

Through the roof, away from doors, openable windows, and air intakes (set clearances apply).

A device on a commercial-kitchen drain that captures fats, oils, and grease (FOG) before the sewer.

By the flow rate / drainage load of the fixtures connected to it.

Capturing oil, sand, and flammable liquids at garages, repair shops, and car washes.

At least ¼ inch per foot.

The top of the trap's outlet, where water spills over — the top of the trap seal.

The seal is below the 2-in. minimum (likely siphoned), so it can pass sewer gas.

Keeping the vent opening away from windows/intakes so sewer gas doesn't re-enter the building.

A relief vent connecting a drainage stack to its vent stack to equalize pressure on tall buildings.

Determining whether the vent must be upsized (over 40 ft) and its required size.

The developed length of the vent and the drainage fixture-unit load it serves.

An oversized horizontal drain that vents fixtures (like floor drains) where conventional venting is impractical.

The horizontal drain from the trap weir to the vent connection.

Loss of a trap seal caused by flow in a connected pipe pulling water out of the trap.

Positive pressure downstream pushing the trap seal back up and out of the fixture.

A vent stack with relief/yoke vents that equalize pressure.

A cylindrical trap with a large seal; generally prohibited except as a special interceptor.

The stack vent (the dry portion that vents the stack through the roof).

Fewer vent pipes — the drain doubles as the vent — when sized and arranged per code.

No more than one pipe diameter total, or the trap can self-siphon.

The trap holds a seal against sewer gas; the vent keeps the seal from being siphoned or blown out.

A temperature & pressure (T&P) relief valve, which opens on excess heat or pressure.

About 210°F (temperature) and 150 psi (pressure).

The full size of the valve outlet — it is never reduced.

Runs downhill, not trapped or valved, no threads on the end, terminates with an air gap ~6 in. above the floor/drain.

So no one can cap or plug it, which would defeat the relief valve.

To absorb the volume of thermally expanding hot water on a closed system, protecting the heater and relief valve.

A check valve, pressure-reducing valve, or backflow preventer on the supply that traps expansion.

About 120°F to limit scald risk (higher storage with a mixing valve fights Legionella).

Where a leak would damage the structure; the pan drains to an approved location.

In high-seismic areas (e.g., much of California); typically two straps, upper and lower third of the tank.

The International Fuel Gas Code (IFGC) and NFPA 54 (National Fuel Gas Code).

Black steel, listed CSST (bonded), copper where the gas is non-corrosive; PE for underground only.

A capped nipple below the gas line near the appliance inlet that catches moisture and debris.

Within about 6 ft of the appliance, in the same room, accessible.

By appliance load in BTU/hr (÷ ~1,000 BTU/ft³ for natural gas) over the longest run, from the code tables.

About 1,000 BTU per cubic foot.

To dissipate electrical energy (lightning/arc) and prevent a puncture that could leak gas.

At 5 ft deep or more (unless cut entirely in stable rock).

Sloping, benching, shoring, or a shield (trench box).

A competent person — daily, before entry, and after rain.

Deeper than 20 feet.

At least 2 feet.

Stable rock, Type A (most stable), Type B (medium), and Type C (least stable).

A space like a sewer, manhole, or tank — requiring air testing, ventilation, and an attendant before entry.

No more than 0.2% lead (the system as a whole: ≤0.25% on wetted surfaces).

Lead leaches into drinking water; the Safe Drinking Water Act requires lead-free joints.

Travel = Offset × 1.414 (the run equals the offset).

10 × 1.414 = 14.14 inches.

2.613 (travel = offset × 2.613).

1.155.

Drop = Length × Grade.

1 psi ≈ 2.31 ft of water column; 1 ft of rise ≈ 0.433 psi.

V = πr²L; multiply cubic feet by 7.48 to get gallons.

About 13 psi (30 ÷ 2.31).

Keep a fire watch, an extinguisher, and heat shields; ventilate flux fumes.

So the burner gets enough air to burn cleanly and vent safely (per IFGC/NFPA 54).

A ladder or ramp within 25 ft of any worker.

Ranges, clothes dryers, outdoor grills, and certain listed appliances.

A valve that admits air to prevent a vacuum that could siphon the tank and damage it.

The visible separation at the end of the T&P discharge pipe so a leak is observable and can't be siphoned.

So occupants notice if the relief valve is leaking or discharging — a sign of a problem.

No — it must terminate to the air over an approved receptor, not be hard-piped into the drain.

A valve that blends hot and cold water to deliver a safe, set temperature and prevent scalding.

Higher storage temperature suppresses Legionella; a mixing valve then delivers ~120°F safely.

The International Fuel Gas Code — governs fuel-gas piping, appliances, and venting.

About 7 inches of water column.

Polyethylene degrades from UV and is not rated for above-ground or interior gas use.

60 × ⅛ = 7.5 inches of fall.

To safely release excess pressure or heat before a tank or system fails.

Pressure rises on a closed system, repeatedly tripping the T&P valve and stressing fixtures.

Someone able to identify hazards and authorized to take prompt corrective action.

1½ horizontal to 1 vertical (about 34 degrees).

¾ horizontal to 1 vertical (about 53 degrees).

It equals the offset (the two legs of a 45-45-90 triangle are equal).

About 7.48 gallons.

About 16.3 gallons.

About 43.3 psi (100 ÷ 2.31).

Q = A × V (flow equals cross-sectional area times velocity).

It is the National Fuel Gas Code — companion to the IFGC for fuel-gas piping and appliances.