Plumbing Glossary

A

Anode rod

A sacrificial metal rod inside a tank water heater that corrodes so the steel tank doesn't. Replacing it before it is used up can extend a tank's life; a rotten-egg smell in hot water often points to it. Related →

B

Backflow preventer

A device that stops contaminated water from flowing backward into the drinking water supply, required on irrigation systems and many commercial connections. Most must be tested periodically by a licensed tester.

Bid leveling

Adjusting competing subcontractor bids to the same scope by normalizing inclusions, exclusions, alternates and allowances, so they can be compared fairly before award. Related →

C

Change order

A written change to a construction contract's scope, price or schedule. Clear scope and leveled bids reduce plumbing change orders.

Cleanout

An accessible capped opening in a drain line that lets a plumber clear blockages or run a camera. Missing or buried cleanouts make drain work slower and more expensive.

D

Developed length

The total length of a pipe run measured along its centerline, including fittings. Longer developed length means more pressure loss, which affects supply pipe sizing.

DFU (drainage fixture unit)

A load value the plumbing code assigns to each fixture to size drain, waste and vent piping. Totals determine the minimum size of branches, stacks and building drains. Related →

E

Expansion tank

A small tank on the water heater supply that absorbs the water's thermal expansion in a closed system (one with a PRV or check valve). It protects the heater, T&P valve and fixtures.

F

First-hour rating (FHR)

How many gallons of hot water a tank water heater can deliver in one hour starting full. Match it to your household's peak hour of use when sizing. Related →

G

Galvanized pipe

Zinc-coated steel water pipe common in homes built before about 1970. It corrodes from the inside, causing low flow, rusty water and leaks, and is usually worth replacing. Related →

Grease interceptor

A tank that separates fats, oils and grease from commercial kitchen wastewater before it reaches the sewer. Sizing, placement and maintenance are set by the plumbing code and the local pretreatment program. Related →

H

Hunter's curve

The probability-based curve that converts total water supply fixture units into an estimated peak demand in gallons per minute, used because not every fixture runs at once. Related →

Hydro jetting

Cleaning a drain or sewer line with high-pressure water to remove grease, scale and roots. Best paired with a camera inspection before and after.

Hydrostatic test

A test that plugs the sewer and fills the under-slab drains with water to see whether the system holds. A dropping level indicates a drain leak. Related →

I

Impact fee

A one-time charge many Texas cities and utilities levy on new connections to fund water and wastewater capacity. It can be a large, easily overlooked line in a commercial budget.

IPC (International Plumbing Code)

A model plumbing code published by the International Code Council and adopted by many U.S. jurisdictions, often with local amendments.

L

Lift station

A pump system that raises wastewater to a higher sewer when gravity flow isn't possible, such as on sites where the public sewer is too shallow.

M

Meter size

The size of the water meter serving a property, which limits peak flow and sets the monthly base charge and tap fees. It should be sized from fixture-unit demand, not guessed. Related →

O

Owner's representative

An independent advisor who protects a building owner's interests on design, bids, change orders and installation quality. Related →

P

PEX-A

Cross-linked polyethylene pipe made by the peroxide method. It is the most flexible PEX type and uses expansion fittings that keep the bore open; a common Central Texas repipe material. Related →

PEX-B

Cross-linked polyethylene pipe made by the silane method. It is stiffer than PEX-A and usually joined with crimp or clamp fittings that slightly reduce the inside diameter. Related →

Polybutylene (PB)

A gray flexible plastic supply pipe used widely from about 1978 to 1995 that is prone to sudden failure. Homes that still have it should plan a repipe. Related →

PRV (pressure-reducing valve)

A valve where the water service enters the house that lowers street pressure to a safe level. The plumbing code calls for one when static pressure exceeds 80 psi; they typically last around 7–12 years. Related →

R

Recirculation pump

A pump that moves hot water through the piping so it reaches distant fixtures faster. Controls such as timers or on-demand buttons keep energy use reasonable.

RMP (Responsible Master Plumber)

A Texas master plumber licensed by TSBPE who carries the required insurance and is responsible for a plumbing company's work. Sasquatch Plumbing Consultant is led by an RMP. Related →

Rough-in

The construction stage when supply, drain, waste and vent piping are installed in walls and floors before they close. The best time for a third-party review.

RPZ (reduced pressure zone assembly)

A high-hazard backflow preventer used where contamination risk is significant, such as many commercial and irrigation connections. It requires periodic testing.

S

Scale

Mineral deposits, mostly calcium carbonate, left by hard water when it is heated or evaporates. Scale shortens water heater life, clogs tankless heat exchangers and fouls fixtures. Related →

Sediment

Loose mineral and debris that settles in the bottom of a tank water heater. It causes popping noises, lost capacity and overheating of the tank bottom; flushing removes it.

Sewer camera inspection

A video inspection of drain and sewer lines that shows cracks, roots, sags, separated joints and blockages. It should back up any large sewer repair recommendation.

Slab leak

A leak in water or drain piping beneath a concrete slab foundation. Expansive clay soils in Central Texas and San Antonio make them common. Related →

Softener (water softener)

Equipment that removes hardness minerals from water by ion exchange, protecting water heaters and fixtures. It should be sized to hardness and peak flow.

T

T&P valve (temperature and pressure relief valve)

A safety valve on a water heater that opens if temperature or pressure gets too high. It must discharge through an approved line to a safe location.

Takeoff

A detailed count and measurement of every fixture, pipe, fitting and piece of equipment on a set of drawings, used to estimate or check bids. Related →

Tap fee

A utility charge to connect a property to the public water or sewer main, usually scaled to meter or connection size.

Temperature rise

How many degrees a water heater must raise incoming water to reach the set temperature. Tankless units are sized by flow at the winter temperature rise. Related →

Top-out

The construction stage when the plumbing above the slab, including vents through the roof, is complete and tested, before insulation and drywall.

Trap arm

The section of drain between a fixture's trap and the vent. Its length and slope are limited by code so the trap seal isn't siphoned.

Trim-out

The final construction stage when fixtures, faucets, trim and water heaters are set and the system is put into service.

TSBPE

The Texas State Board of Plumbing Examiners, the state agency that licenses and regulates plumbers in Texas. Licenses can be verified at tsbpe.texas.gov.

Type L copper

Medium-wall copper tube widely used for water supply piping. It is thicker than Type M and a premium choice for repipes and commercial work. Related →

U

UPC (Uniform Plumbing Code)

A model plumbing code published by IAPMO. Austin and many Central Texas cities enforce it with local amendments. Related →

V

Value engineering

Finding lower-cost ways to deliver the same function and performance on a project without sacrificing code compliance or quality. Related →

Vent stack

A vertical pipe that admits air to the drain system and carries sewer gases out through the roof, protecting trap seals and allowing drains to flow freely.

W

Water hammer

A banging noise caused by a pressure surge when flowing water stops suddenly. High pressure, loose pipes and fast-closing valves are common causes.

WSFU (water supply fixture unit)

A load value the plumbing code assigns to each fixture for sizing water supply piping. Totals are converted to peak demand using Hunter's curve. Related →