In this guide: Balance first · Lower the water · Clear the plumbing · Protect equipment · Cover it · Calculators
Winterizing protects your pool from the one thing that does the most expensive damage: water freezing inside pipes and equipment. A careful close in the fall saves a costly repair — and a much easier open in spring. The steps are the same for in-ground and above-ground; the plumbing detail differs.
Balanced water sitting all winter won't stain, scale, or corrode. Adjust pH, alkalinity, and calcium into range, and bring sanitizer up (or add a winterizing/algaecide kit) a few days before closing. Water you leave slightly off will be far worse by spring.
For pools that freeze, drop the level below the skimmer and returns (typically 4–6 inches, or per your cover type) so expanding ice doesn't crack the skimmer. Don't drain the pool completely — a full pool's weight resists ground pressure, and an empty in-ground shell can even float or heave.
This is the step that prevents cracked pipes. Blow the water out of the lines (a shop vac or blower), then seal the returns with winter plugs and add non-toxic pool antifreeze to in-ground lines where recommended. Above-ground pools usually have the hoses disconnected and drained instead.
Empty the pump, filter, heater, and chlorinator — remove drain plugs and store them in the pump basket so you find them in spring. Backwash and drain the filter (bring cartridges indoors). Store the pump somewhere dry if you can. Any water left in equipment is what freezes and cracks a housing.
A secure winter cover keeps out debris, blocks sunlight (which suppresses algae), and protects the water you balanced. A good cover also cuts evaporation and heat loss, and it's the biggest lever on your off-season and running costs — the same reason covers pay for themselves in heating savings during the season.
These calculators turn the steps above into your exact numbers:
This guide is built on published health codes, national standards, and government energy guidance. For the exact equations behind the linked calculators, see our formula reference.
This guide is general information, not a substitute for your local health code or a licensed professional. Always follow the dosing instructions on your chemical labels and confirm readings with a test kit.