Reference
Plumbing glossary - terms a Dillsburg homeowner actually needs.
A plain-English reference for the plumbing words you'll see on quotes, invoices, code reports, and inspection forms in Central PA. Written by the master plumbers at Premier Dillsburg Plumber. If a term isn't here and you want it explained, email emmagrace3270@gmail.com and we'll add it.
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- AAV
- Air Admittance Valve. A one-way valve that allows air into a drain to prevent siphoning of trap seals, used where a vent stack can't be run to the roof. Must be accessible and rated for the application.
- Anode rod
- A sacrificial magnesium or aluminum rod inside a tank water heater that corrodes preferentially so the steel tank does not. Replace every 3 to 5 years; failure to replace is the #1 reason water heaters fail before year 8.
- Backflow preventer
- A device that prevents non-potable water from flowing back into the potable supply. Required by code on irrigation, boilers, and commercial connections. RPZ and double-check are the most common types.
- Black iron
- Schedule 40 carbon steel pipe with a black mill scale finish. Standard material for natural gas and propane piping in residential applications.
- Cleanout
- A capped opening in a drain line that allows access for snaking, jetting, or camera inspection. Required by code at specific intervals on horizontal runs and at every change of direction over 135 degrees.
- CSST
- Corrugated Stainless Steel Tubing - flexible gas piping (TracPipe, Gastite, etc.) that installs faster than black iron. Must be electrically bonded to the building grounding system.
- Dielectric union
- A fitting with a non-conductive insulator between dissimilar metals (e.g. copper to galvanized steel) to prevent galvanic corrosion.
- FOG
- Fats, Oils, and Grease. The leading cause of sewer line clogs, especially in restaurants and households that pour cooking grease down the drain.
- Hard water
- Water containing dissolved calcium and magnesium minerals. Central PA averages 8 to 18 grains per gallon, which scales heat exchangers, water heaters, and shower heads. Treated with a softener.
- Hydro jetting
- High-pressure water cleaning of drain and sewer lines using a 3,500 to 4,000 PSI jet through a steerable nozzle. Removes grease, scale, and roots without breaking the pipe.
- Hydrostatic pressure
- Water pressure caused by the weight of water in soil or against a foundation. Drives basement leaks and sump pump load. Reduced by exterior drainage and interior weeping tile to a sump.
- Lateral
- The sewer line connecting a house to the municipal main or septic tank. Typically owned and maintained by the property owner from the foundation to the connection point.
- Manifold (PEX)
- A central distribution point for PEX plumbing where each fixture has its own dedicated line, allowing isolation and balanced pressure. Sometimes called home-run plumbing.
- PEX
- Cross-linked polyethylene tubing used for water supply lines. PEX-A (made via the Engel method) is the most flexible and freeze-tolerant; PEX-B (Silane) is stiffer and lower-cost.
- Pinhole leak
- A microscopic perforation in copper supply pipe caused by chemical erosion, electrolysis, or cavitation. Common in 30+ year old soft copper and behind walls or under slabs.
- Pressure regulator (PRV)
- A device that reduces incoming municipal water pressure to a safe range (typically 50 to 80 PSI) for residential plumbing. PRVs are required when supply pressure exceeds 80 PSI.
- Re-pipe
- The process of replacing all supply or drain piping in a building, typically with PEX or copper for supply or PVC for drain. Whole-house re-pipes take 1 to 3 days.
- Snake (drain auger)
- A flexible cable with a cutting head that mechanically clears clogs in drain lines. Hand-cranked or motorized; sized from 1/4-inch (sink) to 5/8-inch (sewer main).
- Sump pump
- A pump installed in a basement or crawlspace pit (the sump basin) to remove groundwater that collects below the foundation. Primary, battery-backup, and water-powered varieties.
- T&P valve
- Temperature and Pressure relief valve - a safety device on water heaters that opens if either pressure or temperature exceeds setpoints. Must discharge by gravity to a safe location.
- Tankless water heater
- An on-demand water heater that heats water as it flows through, with no storage tank. Gas and electric versions; typically lasts 18+ years with annual descaling.
- Trap
- A U-shaped section of pipe under every fixture that holds water to prevent sewer gas from entering the building. Must remain primed (filled with water) to function.
- Trenchless sewer repair
- Repair or replacement of buried sewer lines without excavating the entire run. Includes CIPP (cured-in-place pipe) lining and pipe bursting.
- Vent stack
- The vertical pipe extending through the roof that allows sewer gases to escape and equalizes pressure in the drain system. Required for proper drainage.
- Water hammer
- A loud banging in pipes caused by a sudden stop in water flow (often from a quick-closing valve). Solved with arrestors, secured pipes, or a pressure regulator.
- Water softener
- An ion-exchange system that removes calcium and magnesium from water using a bed of resin beads regenerated with salt. Reduces scale buildup in fixtures and appliances.
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