Water level dropped after I covered pool for winter

[Silvestor]

Closed my pool last week, but today I noticed the water level is much lower under the cover. Is it normal evaporation or do I have a leak?

 

[syedsam]

Unlikely to be evaporation in cold weather. Could be a small liner tear or leak at the return line plugs.

 

[Manikshaw]

Check around the cover edges sometimes rainwater on top pushes pool water out if cover isn’t secured tight.

 

[John Faulkner]

I’d do a bucket test inside the covered pool just to confirm if it’s really losing water.

 

[George Kelly]

When the water level drops after closing, another thing to check is whether the cover pump or siphon hose (if you’re using one) might be accidentally pulling water from underneath instead of just from the top. It’s not super common, but it happens if the setup shifts during heavy rain. Before assuming it’s a leak in the pool itself, I’d rule out any equipment or cover drainage causing the loss.

 

[Jacob Foster]

It’s usually not normal evaporation in cold weather, so I’d check a few things first. Make sure the cover pump or any siphon setup isn’t accidentally pulling water from the pool itself. Also inspect the skimmer and return plugs, sometimes a small leak there or a loose liner can let water escape.

 

[John Harrison]

A drop like that isn’t usually normal evaporation in cooler weather. First, check your cover setup, if you’re using a cover pump or siphon, make sure it’s only removing water from the top, not pulling from underneath. Also inspect skimmer and return plugs, and any liner seams near the edges. Small leaks or loose plugs are often the culprit. Doing a simple bucket test under the cover can help confirm if it’s a true leak or just equipment/cover-related loss.

 

[Liam Brooks]

I had the same thing happen a couple of winters ago and it turned out to be a loose return plug that was slowly seeping water. At first, I thought it was just normal settling or evaporation, but once I pulled the cover back in spring, the water had dropped a lot more than expected.

If you can safely peek under the edge of the cover, check if the waterline is sitting below the returns or if the plugs look damp. Sometimes even a tiny air gap or cross-threaded plug can cause a slow loss that adds up over weeks.