Inground & Above-Ground Swimming Pool Plumbing Parts

Repair, replace, and upgrade your pool's plumbing system with pool plumbing parts from Waterway, Pentair, Hayward, Waterco, CMP, AquaStar, and Lasco. PST Pool Supplies stocks the fittings, valves, gaskets, and connectors used in residential and commercial pool plumbing systems — multiport valves, eyeball fittings, barb adapters, square-ring seals, wall fittings, schedule 40 plugs, and more, starting from $9.90.

The most critical plumbing valve in a pool system is the multiport valve (MPV) — it controls filter operation modes (filter, backwash, rinse, recirculate, waste, closed). The Pentair sand filter MPV and Baker Hydro/Waterco MPV are direct replacement valves for their respective sand filter brands — using the correct brand MPV is essential for proper port alignment and flow rates. Eyeball fittings (1.5" and 2" threaded) are the adjustable directional fittings installed in return ports — they direct return flow to create pool circulation and can be angled to improve mixing or assist skimming. Barb adapter fittings connect flexible hose to rigid PVC plumbing — used extensively in above-ground pool plumbing and for connecting cleaner hoses, solar systems, and bypass lines. Buna-N square rings are the rectangular-profile seals used in MPV spider gaskets and certain pump port connections — failing square rings cause MPVs to leak between ports, sending unfiltered water to the pool during backwash cycles or bypassing the filter entirely. Schedule 40 plugs (threaded PVC) are used to cap off unused ports in manifolds, equipment bypasses, and winterization plugs. AquaStar and CMP wall fittings are the inlet and outlet fittings installed in pool walls for main drains, returns, and vacuum ports. For general pool equipment parts, see our pool replacement parts collection.

Most pool plumbing is Schedule 40 PVC — glued with PVC primer and cement and rated for the pressure and temperature ranges of pool circulation systems. Threaded fittings in pool plumbing should use PTFE thread tape (Teflon tape) on male threads, not pipe dope, to prevent seizing and allow disassembly for future service. When replacing MPVs, shut off the pump and relieve system pressure before removing the valve — MPVs on pressurized sand filters can retain significant pressure. Eyeball fittings and wall fitting gaskets are common sources of small return-line leaks — inspect the gasket behind the fitting's flange if you notice water loss near a return port. Buna-N square rings in MPVs should be replaced at least every 3–5 years or whenever port-to-port leakage is observed during normal filter operation.

Shop pool plumbing parts at PST Pool Supplies and keep your pool's circulation system tight and efficient.