The right moves in the final weeks of use decide what condition a private outdoor pool will be in come next spring. Here’s what matters most.
Seen from the outside, a pool can look flawless right up to the last swim of the season. That’s because summer isn’t actually when the worst damage shows up — the pool gets used and checked daily during that time. Real problems tend to emerge during the shift into winter dormancy, when small management mistakes pile up over months of inactivity and turn into structural issues that are hard to catch in time.
An unused pool, in other words, isn’t simply on pause. For weeks or months, it stays exposed to chemical and physical stress that keeps working on it even without swimmers around.
Rebalance the Water Before Shutting Down
Closing the pool with water in the same condition as the last swim is one of the most common — and costly — mistakes to fix later. Before the seasonal shutdown, it’s worth bringing every value back into range:
- pH between 7.2 and 7.4: outside this range, water can corrode gaskets and metal parts, or encourage limescale and cloudiness.
- Alkalinity and calcium hardness under control, to stop the water from staying aggressive toward surfaces all winter long.
- Adequate chlorine and stabilizer levels, so the pool doesn’t offer ideal conditions for algae to return in the first weeks of shutdown.
Skipping these checks before closing means letting the water work — on its own — against linings and technical components for the entire cold season.
Water Level Matters More Than the Cold
When people think about winterizing a pool, frost is usually the first thing that comes to mind. Yet for many in-ground pools, the real danger comes from the surrounding soil.
Industry technical sources agree on one point: draining the pool completely is almost always a mistake. Once the pool is empty, it loses the hydrostatic pressure that water exerts on the walls and floor. That opens the door to pressure from rain-saturated soil pushing back, with a real risk of structural sinking, cracking, or deformation.
The most common practice among industry professionals is to:
- Never fully drain the pool — the water itself acts as a natural counterweight to the pressure from the ground.
- Lower the water level only where needed (typically 10 cm below skimmers and inlets) in areas with harsh winters, to protect pipes and equipment from freezing.
- Visually inspect the structure before closing, to catch any early signs of movement or subsidence.
Covers Keep Working Even When the Pool Doesn’t
Not all protection requires repeated manual work. A well-chosen cover keeps doing its job even while the pool is closed, without needing constant supervision.
According to data from leading manufacturers in the sector, thermal and bubble covers can cut water evaporation by up to 90-95% under the most unfavorable conditions, which also reduces the amount of chemical product needed for top-ups.
At the same time, heat loss — which overnight can reach around 70% of the heat built up during the day — gets contained, along with direct exposure to UV rays, debris, and weather that would otherwise wear down linings and components.
Why Water Quality Matters So Much
There’s still a common assumption that caring for pool water is only about keeping it clear and swimmable. The technical data and guidance tell a different story: how the water is managed in the weeks before closing has a direct impact on the durability of linings, joints, equipment, and even the pool’s balance with the surrounding soil.
That’s why pre-winter maintenance deserves to be treated not as a season-end formality, but as the single most decisive step in a pool’s yearly care — the one that truly determines how long the structure will hold up over time.
Sources: ibluepiscine.it, edilfare.it, piscineitalia.it, momentospiscina.com, blogpiscine.com, osnaghipiscine.it, quimipool.com, favarettigroup.it
Image by mrsiraphol on Magnific
