Plumbing words, in plain English

A to Z

Aerator

The small screen that screws into the end of a faucet. It mixes air into the stream and it is the first thing to check when one faucet loses pressure, because hard water blocks it.

Angle stop

The small shutoff valve under a sink or behind a toilet. It isolates that one fixture so the rest of the house keeps its water.

Anode rod

A sacrificial rod inside a water heater tank. It corrodes instead of the tank, and once it is used up the tank starts corroding itself. More on this

Backflow preventer

A device that stops water flowing back into the supply. It matters most where irrigation or equipment connects to the house water.

Brine tank

The second tank beside a water softener, holding the salt. The softener draws brine from it to recharge the resin that removes hardness. More on this

Caliche

A cemented layer in desert soil. It makes trenching hard and makes it harder to bed a buried pipe evenly, which is one reason Valley sewer lines settle unevenly. More on this

Cartridge

The replaceable insert inside a single lever faucet or shower valve that controls flow and temperature. A dripping faucet is very often just this.

Cleanout

A capped access point on a drain or sewer line, usually outside. It is how a line gets opened and inspected without going through the house.

Expansion tank

A small tank that gives heated water somewhere to expand into. Without one, pressure climbs every time the water heater runs. More on this

First hour rating

How much hot water a tank can deliver in one hour starting full. It matters more than the gallon number on the side, because it includes how fast the unit reheats. More on this

Flange

The fitting that joins a toilet to the drain pipe in the floor. A failed flange is why a toilet rocks and why it leaks at the base. More on this

Flapper

The rubber seal at the bottom of a toilet tank. When it stops sealing, water passes into the bowl silently, which is the most common cause of a bill that climbs for no reason.

Grains per gallon

The usual unit for water hardness in the United States. Water quality reports sometimes give hardness in parts per million instead; divide by about 17 to convert. More on this

Hose bib

An outdoor faucet. In the Valley they take full sun year round, which is why their washers and packing fail faster than indoor valves. More on this

Ion exchange

How a salt based softener works. It swaps the hardness mineral in the water for sodium or potassium held on resin inside the tank. More on this

Manifold

A junction where one supply line splits into several, each with its own shutoff. It makes isolating one part of the house straightforward.

P-trap

The curved section of drain pipe under a fixture. The water sitting in it is what keeps sewer gas out of the room, which is why an unused bathroom starts to smell once it evaporates.

PEX

A flexible plastic supply pipe used widely in newer houses. It is run differently from copper, which changes how a repair or a repipe is approached.

Pressure regulator

A valve on the main supply that holds house pressure down to a safe band. They wear out, and they usually fail by letting pressure climb. More on this

psi

Pounds per square inch, the unit water pressure is measured in. Household fixtures are built for roughly 40 to 80 psi.

Reverse osmosis

A filtration system, usually under one sink, that produces drinking and cooking water. It treats that one faucet rather than the whole house. More on this

ROC

The Arizona Registrar of Contractors, the state body that licenses contractors and keeps the public register. Ours is ROC #359690. More on this

Scale

Mineral left behind by hard water. Inside a water heater it insulates the burner from the water; on a tankless heat exchanger it costs you output. More on this

Sediment

Grit and mineral that settles at the bottom of a tank or collects in a filter. How much comes out of a flush tells you how overdue the flush was.

Slab leak

A leak in a supply line running beneath the concrete slab a house sits on. A warm floor and a bill that climbed are the classic signs. More on this

Softener loop

The stubbed-out pipes a builder leaves in the garage so a softener can be installed later. It is preparation, not equipment. More on this

Static pressure

The pressure in the system with no water moving. It is what you read with a gauge on a hose bib with everything in the house closed.

T and P valve

The temperature and pressure relief valve on a water heater. It lets water out if either goes too high, and a valve that weeps is usually reporting a pressure problem. More on this

Tankless

A water heater that heats water as it flows through, with no stored tank. It is sized by flow rather than by gallons held. More on this

Thermocouple

A safety part on a gas water heater that senses the pilot flame and shuts the gas off if it goes out. A pilot that will not stay lit often points here.

Vent stack

The pipe that lets air into the drain system. Without it drains gurgle, glug and empty in surges rather than running freely.

Water hammer

The bang when moving water is stopped suddenly by a fast closing valve. Arrestors absorb the shock at the fixture causing it. More on this

Wax ring

The seal between a toilet and its flange. When it fails, water appears at the base of the toilet rather than anywhere obvious.