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How Far Do You Lower the Water in an Inground Pool for Winter?
Active Pool Supply · Updated September 22, 2026
For a solid winter cover, a few inches below the skimmer opening, commonly 4 to 6. For a mesh or solid safety cover, the cover manufacturer's manual decides it, and the number is a floor rather than a target: several brands void the warranty if the water sits more than about 18 inches below the top of the pool, because the water is what supports the cover under snow. With an Aquador or a skimmer plate already fitted, you may not need to lower it at all. Never drain an inground pool.
Start with what kind of cover you have
There is no single number, and anyone who gives you one has not asked what is going on the pool. The three cases are genuinely different.
| Cover | Where to put the water | Why |
|---|---|---|
| Solid winter cover | About 4 to 6 in below the skimmer opening | Freeze protection. The cover keeps precipitation out, so the level will not climb. |
| Mesh safety cover | Follow the cover's manual. Commonly no more than about 18 in below the top of the pool | The water supports the cover under a snow load. Too low strains the cover and the springs. |
| Solid safety cover | Follow the cover's manual. Several brands want 12 to 16 in below the top of the pool | Same support reason, and solid panels shed rather than drain. |
| Fiberglass shell, or an automatic cover | Leave it full, or close to it | The usual advice is wrong here. Check with the builder. |
Why the numbers online disagree, and how to read them
This is the part that makes the topic confusing, and it is not really a disagreement about depth.
Sources measure from three different starting points and almost never say which one they mean. Cover manufacturers measure down from the top of the pool or the deck. Retailers measure down from the skimmer mouth. Some measure down from the tile line. A skimmer throat already sits several inches below the coping, so "12 inches below the skimmer" is a deeper level than "12 inches below the deck", and a figure that sounds cautious in one system can land past a cover manufacturer's warranty limit in another.
The direction differs too, and this matters more than the inches. A cover manufacturer's number is a maximum you must not go past. A retailer's number is a target to hit. They are not the same kind of instruction.
No source we could find publishes a dependable inch-for-inch conversion between the skimmer mouth and the top of the pool, so we will not invent one. If your cover's manual gives a figure from the top of the pool, measure it from the top of the pool.
The way to hold all three in your head
- A floor set by the cover. Do not go below what the cover manufacturer allows. For safety covers that is commonly about 18 inches from the top of the pool, and several brands say in as many words that lower voids the warranty.
- A ceiling set by the freeze. Go far enough that the skimmer and the returns are not holding water, unless a plug or a faceplate is doing that job instead.
- A note about mesh. Mesh drains through, so the level climbs all winter. Set it once and check it again in a month.
Skimmer plugs, Gizzmos and Aquadors
You will read that a skimmer device means you do not need to lower the water at all. As a blanket claim that is wrong, because the two common devices do opposite jobs.
A Gizzmo threads into the skimmer's plumbing and is a sacrificial crush space: ice forming in the skimmer collapses the Gizzmo instead of the skimmer wall. Its own instructions call for the water to be below the skimmer and the skimmer drained before it goes in. It does not remove the need to lower the water. It is one layer among several.
An Aquador works from the other side, sealing the skimmer mouth so water never enters. Fitting the faceplate for the first time does need the water dropped an inch or two so the plate can be screwed on. After that the plate stays put permanently and the lid snaps over it every autumn with no draining at all. So "no need to lower it" is true of an Aquador from the second year onward, and not true in the first.
Never drain an inground pool
An empty inground pool is not a safe inground pool. Groundwater presses up under the shell all year, and the weight of the water inside is what holds it down. Take the water out and the shell can float: a gunite pool can lift and heave the deck around it, and a vinyl liner left dry in the sun can shrink until it will not stretch back into the corners.
An above ground pool has the same instruction for the opposite reason. There, the water holds the walls in shape from the inside. Either way, lower the level, never empty it.
If there is a real reason to empty a pool, such as a liner replacement, that is a job with a hydrostatic relief valve and a plan for the groundwater, and it is not a winter job.
After it is closed
Check the level again once in midwinter, especially under mesh. If a solid cover has standing water on it, get it off with a cover pump: standing water is heavy enough to drag a cover into the pool, and it is a drowning risk in its own right.
If an ice sheet has formed, leave it alone. Breaking it up does more damage than the ice does.
Products in this guide
Questions
How far below the skimmer should the water be?
For a solid winter cover, about 4 to 6 inches below the skimmer opening. For a safety cover, ask the cover's manual instead, because its limit is measured from the top of the pool and is a floor you must not go below rather than a depth to aim for.
Why do the numbers I find online disagree so much?
Because they are measured from three different places and almost nobody says which. Cover manufacturers measure down from the top of the pool or the deck. Retailers measure down from the skimmer mouth. Some measure from the tile line. A skimmer throat already sits some inches below the coping, so "12 inches below the skimmer" and "12 inches below the deck" are not the same depth. No source publishes a reliable conversion between them, so we do not either.
Can I drain my inground pool for the winter?
No. The water in the pool is what holds the shell down against the groundwater around it. Empty, a gunite shell can float and heave the deck with it, and a vinyl liner left dry can shrink so much it will not go back. This is the opposite reason from an above ground pool, where the water holds the walls up, but the instruction is the same.
Do I need to lower the water if I have a Gizzmo or an Aquador?
They do opposite jobs, and the blanket answer of "no" is wrong for one of them. A Gizzmo goes into a drained skimmer and gives ice something to crush, so its own instructions want the water below the skimmer first. An Aquador seals the skimmer mouth from outside: fitting the faceplate the first time needs a 1 to 2 inch drop, and after that the plate stays on and the lid snaps over it each year with no draining.
What about a fiberglass pool?
Leave it full. Fiberglass is the case where the usual advice is wrong: the shell needs the water in it, and dropping the level 12 to 18 inches is exactly what you should not do. Same for a pool with an automatic cover.
The water rose over winter. Is that a problem?
Under mesh, yes, it is expected: mesh drains through, so rain and snowmelt go into the pool and the level climbs. Check it through the winter. Under a solid cover the level should not climb, but snowmelt sitting on top can push the cover down until it cannot drain, which is what the cover pump is for.