Water level keeps rising after I lower it for winter!

[Zephyr]

This is my first year closing the pool myself and I ran into something weird. I drained the water down below the skimmer line like everyone suggests, but a few days later the level had crept back up almost to normal. We didn’t get much rain, so I’m confused how it filled itself back up. Do I have some kind of groundwater issue or did I miss a step in the closing process?

 

[Freddie]

This is my first year closing the pool myself and I ran into something weird. I drained the water down below the skimmer line like everyone suggests, but a few days later the level had crept back up almost to normal. We didn’t get much rain, so I’m confused how it filled itself back up. Do I have some kind of groundwater issue or did I miss a step in the closing process?

Double check that your return lines are properly plugged. Sometimes water seeps back in through a poorly sealed line if the plugs aren’t snug. Happened to me once, and I thought I had a leak when it was just the return slowly refilling the pool.

 

[Isabella]

This is my first year closing the pool myself and I ran into something weird. I drained the water down below the skimmer line like everyone suggests, but a few days later the level had crept back up almost to normal. We didn’t get much rain, so I’m confused how it filled itself back up. Do I have some kind of groundwater issue or did I miss a step in the closing process?

That’s not unheard of in areas with a high water table. Groundwater can push its way back into the pool, especially if you don’t have a hydrostatic relief valve in the main drain. It’s basically nature trying to balance pressure.

 

[Ethan Wells]

I’ve seen this happen a couple of different ways, and it can be confusing the first time around. Aside from groundwater or loose plugs, sometimes the issue is as simple as backflow through equipment that wasn’t fully winterized. For example, if the pump or filter still has water inside and isn’t properly drained, that water can slowly trickle back into the pool and bring the level up over a few days.

Another possibility is seepage through the cover if it’s collecting melt or condensation, doesn’t take a ton of extra water for the level to look higher again. It’s worth checking both your plugs and making sure the equipment is dry and sealed off. If your area does have a higher water table, adding a hydrostatic relief valve like Isabella mentioned is a long-term fix, but ruling out the simpler stuff first will save you a lot of worry.

 

[Megan Lawson]

I’ve run into the same head-scratcher before, and it turned out not to be a “mystery leak” at all. Even a small amount of water sneaking back in, whether from a return plug that isn’t quite sealed, leftover water in the filter system, or groundwater pressure- can make it look like the pool is refilling itself.

One quick check you can do is mark the current level and see if it keeps rising. If it does, that usually points to groundwater intrusion. If it stabilises, then it was probably just residual water draining back from the lines or equipment. Either way, it’s worth double-checking your plugs and making sure everything is fully drained before winter sets in.

 

[Ella Robinson]

I mark the water line and check again in 1–2 days. If it rises then levels off, it’s usually groundwater; if it keeps climbing, it’s likely seeping back through a plug/equipment. Tighten plugs/valves, close the line to the pump, and if your area has a high water table, a hydrostatic relief valve helps.

 

[Matthew Collins]

One other possibility that catches a lot of first-time closers off guard is an auto-fill or equalizer line. If your pool has an automatic water leveler tied into the plumbing (or even a manual fill line that wasn’t fully shut off), it can quietly add water back in over a few days. Because it’s slow and steady, it doesn’t look like “filling,” just a creeping waterline.

You can usually spot this by listening near the deck box or skimmer for a faint hiss, or by shutting off the house water feeding the pool and seeing if the level stops rising. If there’s an equalizer line between the skimmer and main drain, that can also allow water to migrate back depending on pressure differences.

The good news is this kind of rise is usually harmless once you identify it. Once the source is isolated and shut off, the level should stay where you set it for winter.

 

[Lily Allen]

The water level rising after draining could be caused by groundwater seeping back into the pool, especially if there’s an issue with drainage or barriers around the pool. I usually recheck the drain lines or make sure the pool cover is sealed tightly. If I’m concerned about groundwater issues, I sometimes use AquaDoc Leak Sealer to ensure no leaks are occurring.

 

[Alma Weber]

Double check that your return lines are properly plugged. Sometimes water seeps back in through a poorly sealed line if the plugs aren’t snug. Happened to me once, and I thought I had a leak when it was just the return slowly refilling the pool.

I’ve seen this happen a couple of different ways, and it can be confusing the first time around. Aside from groundwater or loose plugs, sometimes the issue is as simple as backflow through equipment that wasn’t fully winterized. For example, if the pump or filter still has water inside and isn’t properly drained, that water can slowly trickle back into the pool and bring the level up over a few days.

Another possibility is seepage through the cover if it’s collecting melt or condensation, doesn’t take a ton of extra water for the level to look higher again. It’s worth checking both your plugs and making sure the equipment is dry and sealed off. If your area does have a higher water table, adding a hydrostatic relief valve like Isabella mentioned is a long-term fix, but ruling out the simpler stuff first will save you a lot of worry.

Reading what Freddie and Ethan mentioned, I’ve had that same panic moment before. It turned out not to be mysterious groundwater or the pool magically refilling, but leftover water in the filter and lines slowly draining back in. I also once didn’t tighten a return plug enough and a tiny seep was enough to raise the level a few inches over days. I’d check the simple stuff first like plugs, valves, and making sure the system is fully drained before assuming it’s something bigger.