Pool Losing 1 Inch of Water Per Day? What It Really Means

How Much Water Is 1 Inch Per Day?

An inch doesn’t sound like much until you spread it across the whole pool.

Rough ballpark:

• Smaller/medium pools (around 12′ × 24′):
  about 150–200 gallons per day
• Common 15′ × 30′ or 16′ × 32′ pools:
  about 250–350 gallons per day

Over a week, that can easily be 1,500–2,000+ gallons. So if that 1 inch per day is real and
repeating, it’s not minor.

Can Evaporation Alone Reach 1 Inch Per Day?

Typical Florida evaporation ranges look more like this:

• Unheated, mild days: about ⅛"–¼" per day
• Hot, dry, breezy days: up toward ¼"–⅜" per day
• Heater on + features + cool nights: sometimes around ⅜"–½" per day

To hit a full inch per day from evaporation alone, you’d usually need a perfect storm:

• Hot sun and warm water,
• Dry air and steady wind,
• No cover,
• Spa spillover and water features running a lot.

Even then, that’s on the high side. If you’re seeing about an inch per day, day after day, in normal
conditions, you should treat it as suspicious, not “definitely just evaporation.”

Quick Checks Before You Assume the Worst

Run through these fast:

• Heavy use?
  Big weekend with kids, guests, or dogs in the pool?
  Splash-out alone can drop the level quickly.
• Heater + spillover + features?
  Heater running, spa spilling over all day, fountains or bubblers on?
  That combination drives evaporation way up.
• Weather spike?
  Did you just go from mild to a stretch of hotter, windier, drier days?

If the big drop only happened once right after a rare “perfect storm” of those factors, it might be a temporary
spike. If it keeps happening in normal conditions, that’s different.

Step One: Confirm the Drop Is Real

Before anything else, make sure the 1 inch is real and not just a rough eyeball guess.

1. Turn autofill off if you have one.
2. Mark the waterline on the tile or inside the skimmer.
3. Run the pool normally for 24 hours.
4. Measure how far the level dropped from the mark.

If the mark shows you’re really losing close to an inch again, treat it seriously and move to a bucket test.

Step Two: Use a Bucket Test to Separate Evaporation from a Leak

A bucket test tells you if the pool is dropping faster than evaporation.

Basic idea:

• Put a bucket of pool water on a step and mark:
  • The water level inside the bucket,
  • The water level in the pool.
• Run the pool 24–48 hours the way you normally do.
• Compare how far each waterline dropped.

How to read it:

• Pool drop ≈ Bucket drop:
  Loss is likely evaporation and/or splash-out, even if it feels like a lot.
• Pool drop > Bucket drop (by a clear margin):
  The extra loss is usually leak territory, not just weather.

If you’re seeing around 1 inch per day in the pool but only a fraction of that in the bucket, assume you’re
beyond simple evaporation.

Extra Clues Around a 1-Inch-Per-Day Loss

Alongside the numbers, look for:

• Soft or soggy spots along the outside of the deck or in the yard.
• Areas that stay damp long after everything else dries.
• New deck cracks or settling near the pool’s edge.
• Pump pulling air or losing prime more than it used to.
• Autofill running a lot just to hold level.
• Water bill higher than normal for the season.

One clue alone doesn’t prove anything. But fast loss plus a bucket test gap plus one or two
of these signs should push you firmly into “treat this as a leak” mode.

How Long Can You Ignore an Inch Per Day?

If that inch per day is genuine and repeating, ignoring it is expensive:

• It can wash out soil under the deck.
• It can create voids that turn into cracks and settling.
• It constantly wastes water, chemicals, and heat.
• If the leak is in plumbing, it can eventually damage lines and equipment.

It’s usually cheaper to pay for one proper leak detection visit than to feed a leak for months.

When to Treat 1 Inch Per Day as a Leak

Act like it’s a leak when:

• A marked test shows around 1 inch in 24 hours, more than once.
• A bucket test shows the pool dropping clearly more than the bucket.
• Weather and use don’t explain that kind of loss.
• You see a mix of soft ground, damp areas, deck changes, pump issues, or a busy autofill.

At that point, the main question isn’t “Is it a leak?” It’s:

“Where is it, and what’s the cleanest way to fix it?”

Helpful Tools for Checking a 1-Inch-Per-Day Loss

You don’t need fancy gear, but a few small tools make this easier:

• A sturdy bucket for the bucket test.
• A grease pencil or painter’s tape for marking waterlines.
• Optional: a basic pool leak detection dye kit to check cracks, skimmers, and fittings more closely.
  
  View simple leak detection dye kits

For a full walk-through of the bucket test itself, see
How to Do a Bucket Test for Pool Leaks (Step-by-Step).

Bottom Line

A true 1 inch per day loss is a big number for most Florida pools. Evaporation can be
aggressive in the right conditions, but if your own tests show the pool outpacing a bucket, you’re likely in
leak territory.

A simple mark test plus a bucket test will tell you quickly whether this is just hard-working evaporation or a
problem you need a leak detection pro to track down.

When the numbers and signs line up, it’s better to find and fix the source than keep refilling and hoping it
goes away.