The Pipes Nobody Sees: What's Buried Under Your Pool Deck and Why You Can't Change It Later

Every conversation about pool design starts with the things you can see — the shape, the finish, the water features, the coping stone. Almost no conversation starts with the pipes. That's a problem, because the decisions made underground during a two-day rough-in are the most permanent decisions in your entire pool build.

Change your mind about tile later? You'll write a check. Change your mind about the plumbing layout after the deck is poured? You're breaking concrete and starting over.

Here's what's actually being buried in your backyard, and why it deserves more of your attention than it usually gets.

A typical concrete pool has six categories of plumbing running beneath the deck and inside the shell.

Main drains sit at the deepest point of the pool floor, usually in pairs for safety compliance. They pull water toward the pump for filtration. Two drains spaced at least three feet apart is code — not a luxury — designed to prevent entrapment if a drain cover fails.

Skimmers are the intakes mounted into the pool wall at the waterline. A standard residential pool gets one; larger pools get two or three. Skimmers capture floating debris before it sinks, so sizing and placement directly affect how clean your pool stays between service visits.

Returns push filtered water back into the pool. Their placement, angle, and quantity determine how water circulates — and poor circulation is the single biggest driver of algae growth. A well-designed return layout keeps the whole body of water moving, not just the deep end.

Feature lines serve waterfalls, bubblers, deck jets, scuppers, spillover spas, and any other hydraulic feature you've added. Each one needs its own dedicated line or a shared line sized to handle the combined flow.

Cleaning system ports run underground if you've included an in-floor cleaning system or a pressure-side cleaner with a dedicated booster pump. These lines have to go in before the shell is shot.

Bonding wire isn't plumbing exactly, but it runs along every metal component — rails, ladders, light niches, all equipment — and connects them to a common ground. It's installed at the same phase, and it's just as permanent.

Every inch of pipe has a maximum flow rate before friction loss becomes a performance problem. Undersized pipes mean higher velocities, which mean noise at the returns, increased pump strain, and wasted energy. The difference between 1.5-inch and 2-inch pipe isn't obvious on a blueprint, but it's significant in operation — especially on pools over 20,000 gallons or on equipment pads located far from the shell.

Your equipment pad placement and the distance it sits from the pool directly affect pipe run length, which affects friction loss, which affects pump sizing. This is why a competent designer considers equipment location and the plumbing layout together — not sequentially.

Most homeowners who wish they'd done something differently aren't talking about the finish or the coping. They're talking about things that required plumbing they never put in.

Not enough returns. Adding a second skimmer or two additional returns to improve circulation costs almost nothing during construction. After the deck is poured, each return requires cutting concrete, digging, and re-running pipe back to the equipment pad — typically $1,500–$3,000 per return.

No cleaning system stub-out. If you're not ready to commit to an in-floor cleaning system yet, ask your builder to at least stub out the lines during the rough-in. A stub-out costs a few hundred dollars. Trying to add in-floor cleaning to an existing pool costs $8,000–$15,000 and involves excavation.

Skipping spa jets to save money. A spa without jets is just a raised plunge pool. Jet plumbing has to be in the shell before shotcrete is applied. 'Adding jets later' isn't a realistic option on a concrete pool — you're talking about core-drilling into a finished structure and re-plastering at minimum.

No lines for future water features. That waterfall you're not sure about yet? If the line isn't there now, it's not happening without a jackhammer. Same for deck jets, bubblers, or a scupper wall. The marginal cost during rough-in is low. The cost after the deck is poured is not.

Go through your design with your contractor and ask one question for each potential upgrade: 'If I wanted to add this in five years, what would it take?' If the answer involves breaking concrete, the follow-up is: 'What does it cost to run the line now?'

Almost always, the answer is a few hundred dollars to stub something out or pre-size a pipe for a feature you're uncertain about. That's a reasonable insurance policy against a decision you'll feel strongly about once you're actually using the pool.

A good designer walks you through this automatically — not because they want to upsell, but because they've watched too many homeowners cut corners underground and regret it from day one.

Rock Water Pools designs custom concrete pools throughout Lake Norman, Mooresville, and the greater Carolinas — and we walk every client through the underground decisions before a single shovel hits the ground. Call us at 704-450-1023 to schedule a consultation and start with a plan you won't need to undo later.