Keep an inground pool empty for the shortest time possible — ideally a few days, not weeks. Two things damage an empty pool: groundwater pressure pushing up on the shell (which can crack or "pop" a pool out of the ground), and sun and heat drying the exposed surface, which causes cracking, chalking, and delamination. In Arizona the heat is the bigger everyday risk, especially in summer. Drain only for a reason (a chem wash, repair, or resurface), do the work immediately, and refill as soon as it is done.
What an empty pool is up against.
A full pool is in balance. The weight of the water presses down and holds the shell in place, and it keeps the interior surface wet and cool. Take the water out and both of those things stop.
1. Pressure from below
Concrete pools are built to hold water in, not to hold the ground out. When the water table is high — after heavy rain, near canals and washes, in low-lying lots — groundwater pushes up on the empty shell. The pool can crack, or in the worst case lift out of the ground, which is called a "pop-up." That's why most pools have a hydrostatic relief valve in the main drain. It lets groundwater into the pool instead of under it.
In most of the East Valley the water table is deep and pop-ups are rare. They are not impossible. Risk goes up after monsoon storms and in neighborhoods with irrigation or lakes nearby.
2. Sun and heat from above
This is the Arizona problem. A pool finish is a cement product that wants to stay wet. Exposed to 110° air and direct sun, it dries out, shrinks, and can crack, chalk, or separate from the shell underneath. Fiberglass pool walls can bulge inward without water holding them. Vinyl liners shrink and don't go back. The longer the exposure and the hotter the day, the worse it gets.
So how long is "too long"?
| Situation | How long is reasonable |
|---|---|
| Draining for a chem wash | A day or two. Drain, wash, rinse, refill — done. |
| Draining for a resurface | Roughly one to two weeks, but the surface is being worked the whole time — chipped out, prepped, re-finished — not sitting bare in the sun. The new finish is wet-cured and the pool fills the day after it goes on. |
| Draining to "let it sit" over summer | Don't. Weeks of exposure in Arizona heat is how finishes fail and shells crack. |
| Draining in or right after a monsoon | Avoid if you can. Saturated ground is when groundwater pressure is highest. |
When draining is the right call.
- A chem wash and tile cleaning. Calcium scale and set-in staining can't be fixed with the water in. Acid and chlorine washes are done on a drained pool, and the tile gets cleaned in the same visit.
- A new finish. Resurfacing requires chipping out the old surface — obviously an empty pool.
- Very high total dissolved solids or cyanuric acid. Sometimes the water chemistry is so far gone that fresh water is the only fix. Most Valley pools need a partial or full drain every few years for this reason alone.
- Structural or plumbing repairs below the waterline.
Where the water goes matters. Most Valley cities require pool water to be drained into your home's sewer cleanout, not the street, the alley, or a wash. Your city's website has the rule. A pool company doing the drain handles this for you.
How we keep the empty window short on a remodel.
A remodel is the one time a pool is empty for more than a day, so the schedule is built around it:
- Drain and chip-out — 1 to 2 days. The old finish comes off down to a sound surface.
- Repairs and prep. Cracks, hollow spots, and plumbing or equipment work happen now, while the pool is already open. Doing it all in one drain is the whole point.
- Tile and coping. New waterline tile goes in before the finish.
- Pebble finish — 1 day. The new surface goes on in a single day.
- Next day: acid wash and fill. The finish is washed to expose the pebble and the hoses go in the same day. From there the pool is filling, not drying.
- Startup once it's full. Chemistry is set and the new surface is brushed daily for the first couple of weeks while it cures.
Resurface and tile typically run about one to two weeks start to finish. Many remodels are done in 2 weeks or less; bigger scopes with decking and equipment take longer, and we tell you that up front.
Already drained and stuck?
If your pool is sitting empty — a contractor walked away, a DIY project stalled, the home was vacant — the best thing you can do today is keep the surface shaded and damp (a sprinkler on a timer helps) and get the work scheduled. Text us a photo and we'll tell you what we see.
