One of the most persistent pool maintenance myths is that you should drain your pool entirely for winter. Don’t. Draining a pool fully creates real risks — structural, financial, and chemical — that proper winterization avoids. Here’s why and what to do instead.
Why you don’t drain a pool for winter
1. Hydrostatic pressure can pop the pool out of the ground
An empty in-ground pool has no water weight holding it down. Groundwater in saturated soil exerts upward pressure that can crack the shell or float the entire pool out of place. We’ve seen vinyl-liner above-ground pools collapse from being drained.
2. Plaster surfaces crack from drying
Plaster pools rely on being underwater. Drain them and the plaster shrinks unevenly as it dries, creating spider cracks that fill with water (and freeze) in the first winter.
3. Vinyl liners lose shape
An empty vinyl pool loses the water pressure that holds the liner stretched against the walls. The liner contracts. When you refill, it often doesn’t re-stretch correctly — you end up with wrinkles, gaps, and ultimately needing a new liner.
4. You pay to refill
Refilling 20,000 gallons of water from municipal supply often costs $80–$200, plus the chemicals needed to balance from scratch.
What to do instead: proper winterization
Lower the water level just below the skimmer, blow out the plumbing lines, install freeze plugs, drain the equipment, and cover the pool. The pool stays mostly full all winter. See our winterization tutorial.
When you SHOULD drain (rare)
- Re-plastering or resurfacing — the whole point of draining.
- Replacing a vinyl liner — the old liner has to come out.
- Lowering chemistry that’s out of range — partial drain only (50% max), see our partial drain tutorial.
In all of these scenarios, work with a professional and check the local water table before draining fully.
Winterization chemicals
If you’ve been told to drain your pool fully, reach out to PST Pool Supplies before doing it — we’ll help you confirm whether it’s actually necessary or just an unnecessary expense.