Every gallon of water that leaves your pool and comes back has to travel through a pipe. The pipe looks boring — just white plastic bolted to a wall — but the choice of material, wall thickness, and how it's protected determines whether your plumbing lasts three years or thirty.
Schedule 40 PVC is the baseline — know why
The industry standard for residential and commercial pool circulation is Schedule 40 PVC. Pool codes typically require piping that meets ANSI/NSF Standard 14, which certifies plastic piping for potable and recreational water. Schedule 40 is the floor, not the ceiling. Where pressure, temperature, or mechanical abuse is higher, step up to Schedule 80 — same outside diameter, thicker wall, much more strength.
- Schedule 40 PVC — standard suction and return lines up to ~140°F and ~130 psi at room temperature.
- Schedule 80 PVC — commercial manifolds, high-pressure sections, anywhere with mechanical risk. Gray color by convention.
- CPVC — chlorinated PVC, rated to ~200°F. Used on the hot side of heaters when local code requires it or when salt-cell return is unusually warm.
- Flexible PVC — convenient for curves, but more prone to termite and rodent damage when buried. Avoid under pool decks where you can't re-pull it.
Pipe sizing: bigger is cheaper to run
A counterintuitive fact that homeowners almost never hear: the pump doesn't get to pick its flow. The plumbing picks its flow. Friction loss climbs with the square of velocity, so doubling the flow through the same pipe roughly quadruples the resistance. The practical rule: size the pipe generously on the front end.
- 1.5" PVC → up to ~45 gpm before velocity-related friction and noise take over.
- 2" PVC → up to ~75 gpm.
- 2.5" PVC → up to ~120 gpm.
A variable-speed pump on oversized pipe runs slower for the same turnover and uses a fraction of the energy. Undersized pipe is permanent; you can't un-make that decision without cutting concrete.
Two things that kill PVC in Florida
UV exposure. White PVC left in direct sun will chalk, yellow, and embrittle. Any pipe above grade should be painted with a latex exterior paint or wrapped in UV-resistant sleeving. Pay special attention to the equipment pad where a decade of afternoon sun will eventually crack a fitting at the slightest mechanical stress.
Freeze cycles. It does freeze in North and Central Florida. Pipe subject to freezing should have a continuous slope toward a drain point, so the pump room can be blown down when a hard freeze is forecast. A single split fitting under a deck will leak every spring until someone jackhammers the concrete to find it.
Fittings rules you should never break
- Don't mix schedules at threaded joints. A Schedule 40 male thread into a Schedule 80 female coupling is an easy crack waiting to happen.
- Use unions at the pump, filter, and heater. You will service them. Glued joints at equipment are a service call you'll pay for twice.
- Support long runs. PVC should be strapped every 3–4 feet horizontally. Sagging pipe holds standing water and becomes the first thing to crack.
- Leave a thermal break. Always install 18–24 inches of PVC (or CPVC per manufacturer) between the heater outlet and any plastic plumbing downstream.
Color-coding (why you'll see painted pipe on commercial pads)
Commercial equipment rooms often color-code pipe so operators can read the system at a glance. Common convention: aqua for filtered water, black for main-drain suction, olive green for skimmer/gutter lines, yellow for chlorine, pink for acid, dark brown for backwash waste. On a residential pad, even a few dabs of paint and a labeled valve chart save hours the next time someone unfamiliar works on it.
Rule of thumb before you cut anything: photograph the existing piping first. Every re-plumb job where someone skipped the photo adds 30 minutes and at least one incorrect fitting.