Pool Leak Calculator — Leak Business Academy

Location

Conditions

Water Loss

Pool Size

📍

Location & Water Temperature

Step 1 of 4

ZIP Code *

US ZIP codes only (5 digits)

Valid 5-digit US ZIP required.

Water Temperature — °F *

Take an actual reading with a thermometer

Temperature required (40–110°F).

⚙️

Pool Conditions

Step 2 of 4 — affects evaporation calculation

Wind Shelter

Sun Exposure

Pool Cover

Water Movement

📏

Measured Water Loss

Step 3 of 4 — rainfall fetched automatically

Start Date *

Start date required.

End Date *

End date required.

Select start and end dates above

Total Water Drop — inches *

Measure from your mark to the current water level

Measured water drop is required.

💡 How to Measure

Mark the water level with tape on the pool wall (or use the skimmer).
Turn off any auto-fill valve — it will mask real water loss.
On the end date, measure the total drop from your mark.
Rainfall during the period is fetched automatically.

📐

Pool Dimensions

Step 4 of 4 — used to estimate leak volume only

Optional

Entering dimensions lets the calculator show estimated gallons lost per day. Skipping this does not affect the leak verdict.

Pool Shape

Length — ft

Width — ft

Expected Evaporation

—

in / day

Unexplained Loss

—

in / day

✅

—

Measurement Confidence

—

Measured Loss / Day

—

Unexplained Loss / Day

—

Total Unexplained Loss

—

Rainfall (Auto-Fetched)

—

Measurement Window

—

📡 Weather Data — Averaged Over Measurement Period

Location

—

Total Rainfall

—

Avg Air Temp

—

Avg Dew Point

—

Avg Wind

—

Avg Pressure

—

Days Analyzed

—

Data Source

Open-Meteo Archive

What To Do Next

Fill a bucket with pool water to about 1 inch from the top.
Place the bucket on a pool step — submerged to the same depth as the pool water line.
Mark the water level inside the bucket AND the pool level on the outside.
Turn off the pump and auto-fill. Wait 24–48 hours.
If the pool lost more than the bucket, you likely have a leak.
If both dropped equally, the loss is evaporation — consistent with this result.

Disclaimer: Estimates based on historical weather records and user-entered measurements. Evaporation varies with conditions not fully captured by any model. Always consult a licensed pool leak detection professional for confirmed diagnosis and repair.

Learn More

How This Pool Leak Calculator Works

This tool compares your pool's expected evaporation — calculated from real local weather data — against your actual measured water drop to determine whether a leak is likely.

Enter your ZIP code and the dates you measured your pool water level. The tool retrieves hourly weather records including temperature, humidity, wind speed, and rainfall to estimate how much water your pool should have lost to evaporation using the Meyer evaporation formula — the standard open-water equation for residential pools, based on vapor pressure difference between the water surface and the air, driven by wind speed. Because this tool averages weather data across the full measurement period (including overnight when wind is calm), results will typically read lower than Anderson Manufacturing's estimator, which uses instantaneous daytime conditions. Both are correct for their purpose.

If measured loss significantly exceeds expected evaporation, the calculator indicates that a pool leak may be present.

📋 Professional Tips

Turn off your auto-fill valve before measuring. Even a slow trickle will mask a real leak and make your numbers unreliable.
Measure over at least 7 days for best accuracy. A 1–2 day reading can be skewed by splashing, backwash, or a single evaporation spike.
Rainfall is fetched automatically for your ZIP code and factored into the calculation.
Undetected leaks erode soil, undermine decks, and cause structural damage that compounds over time. Do not delay if you suspect a leak.

What Is Normal Pool Evaporation?

Most outdoor swimming pools lose ¼ inch to ½ inch of water per day due to evaporation. The exact amount varies based on several weather and pool conditions.

🔺 Increases Evaporation

High air temperature
Strong or consistent wind
Low humidity / dry air
Full sun exposure
Water features, fountains, waterfalls
Zero-edge / infinity designs
Pump running continuously

🔻 Reduces Evaporation

High humidity
Wind barriers / screen enclosures
Heavy shade
Pool cover (especially overnight)
Cooler water temperature
Pump off / still water

Because evaporation changes daily with weather conditions, comparing your measured loss to real local weather data is the most reliable way to determine whether your pool is leaking.

Signs Your Pool May Have a Leak

If you're noticing any of the following, your pool may be losing water to a leak rather than normal evaporation:

💧Losing more than ½ inch of water per day
🔁Constantly needing to refill the pool
🌱Wet, soft, or eroded soil around the pool deck
🪨Cracks in the pool shell, tile line, or coping
💨Air bubbles coming from return jets
💸Unexplained increase in water bills
⏸️Water level always stops dropping at the same point
🔧Wet spots around equipment pad or pump

Common leak locations: Skimmer housings · Return fittings · Pool light niches · Underground plumbing · Structural cracks · Main drain fittings

Frequently Asked Questions

How much water should a pool lose per day?

Most pools lose between ¼ and ½ inch per day due to evaporation. Weather conditions — temperature, wind, and humidity — affect this daily. Losing more than ½ inch consistently may indicate a leak.

How can I tell if my pool is leaking or just evaporating?

Measure your pool water level over several days and compare the loss to expected evaporation for your local weather. If water loss significantly exceeds evaporation, a leak may be present. This calculator does that comparison automatically using real local weather data.

Does rain affect pool leak testing?

Yes. Rainfall can temporarily raise the pool water level and mask actual water loss. This calculator automatically retrieves rainfall data for your ZIP code and adjusts the calculation accordingly.

How long should I measure pool water loss?

At least 7 days gives a reliable result because it smooths out daily evaporation fluctuations. This tool accepts measurement windows from 2 to 14 days — longer periods produce higher-confidence results.

Can I add this tool to my phone?

iPhone / Safari: Tap the Share button → scroll down → tap "Add to Home Screen" → tap Add.

Android / Chrome: Tap the three-dot menu → tap "Add to Home Screen" or "Install App" → confirm. The tool opens full screen like a native app.

About Leak Business Academy

Leak Business Academy was created by professional pool leak detection experts with decades of real field experience diagnosing residential swimming pool leaks across Southeast Florida and beyond.

The training and tools developed by Leak Business Academy are based on the H.U.N.T.E.R. Detection System — a systematic method used by leak detection professionals to locate leaks quickly and accurately using hydrophones, pressure testing, dye testing, and acoustic equipment.

This free pool leak calculator was developed to help homeowners determine whether their water loss is normal evaporation or a potential leak — before calling a professional.

Professional leak detection specialists use acoustic listening equipment, dye testing, and pressure testing to locate leaks without damaging the pool structure. Early detection prevents costly structural damage — a small undetected leak can undermine decking and cause foundation damage that costs far more to repair than the leak itself.

Learn more at Leak Business Academy →