01
The purpose
What does this calculator estimate?
Add up every source of water loss — evaporation, splash, backwash, leaks — into one yearly total and cost.
Water Loss & Leaks · E5
Annual Pool Water Loss Cost Calculator
Add up every source of water loss — evaporation, splash, backwash, leaks — into one yearly total and cost.
Measure the inputsEvaporation is almost always the biggest slice — covers attack it directly.
Read the full resultA leak that shows up here as a large slice justifies professional detection fast.
Check the boundaryCompare your total loss to pool volume — losing more than your volume yearly is a lot.
Useful forWater Loss & LeaksPlanningComparisonVerification
Live calculation
Annual loss inputs
✓ Checked May 2026
Enter yearly gallons from each source.
Estimated rate
—
Enter the required values to calculate.
Enter the known values. Let the engine handle the calculation.
✓ Formula checked↻ Live result○ No account needed
Planning estimate only. Confirm product labels, equipment specifications, qualified-professional advice and local requirements before acting.
The result, explained
Use the Annual Pool Water Loss Cost Calculator result with context.
Add up every source of water loss — evaporation, splash, backwash, leaks — into one yearly total and cost.
02
The tool
What information does it use?
- Pool volume: For the percent-of-volume figure.
- Evaporation per year: From the evaporation tool.
- Splash-out per year: From the splash-out tool.
- Backwash per year: From the backwash tool.
- Leak per year: From the bucket test (0 if none).
- Water rate: $ per 1,000 gallons from your bill.
03
The method
How to use this calculator
- Pool volumeFor the percent-of-volume figure.
- Evaporation per yearFrom the evaporation tool.
- Splash-out per yearFrom the splash-out tool.
- Backwash per yearFrom the backwash tool.
- Leak per yearFrom the bucket test (0 if none).
- Water rate$ per 1,000 gallons from your bill.
04
The relationship
The formula in plain English
Total loss = evaporation + splash + backwash + leak
Cost = (total ÷ 1000) × rate per 1,000 gal. Each source shown as a % of the total.05
Worked through
A worked example: 34,000 evap + 2,160 splash + 1,440 backwash + 2,400 leak
- Total = 34,000 + 2,160 + 1,440 + 2,400 = 40,000 gal
- Cost = (40,000 ÷ 1000) × $5 = $200/yr
- Evaporation = 85% of the total
| Source | Gallons/year | % of total | Cost* |
|---|---|---|---|
| Evaporation | 34,000 | 85% | $170 |
| Splash-out | 2,160 | 5% | $11 |
| Backwash | 1,440 | 4% | $7 |
| Leak | 2,400 | 6% | $12 |
| Total | 39,000 | 100% | $200 |
06
Why it matters
How the result supports the next decision
Evaporation is almost always the biggest slice — covers attack it directly.
A leak that shows up here as a large slice justifies professional detection fast.
07
Good inputs
Improve the estimate before relying on it
- Evaporation is almost always the biggest slice — covers attack it directly.
- A leak that shows up here as a large slice justifies professional detection fast.
- Compare your total loss to pool volume — losing more than your volume yearly is a lot.
- Backwash and splash are usually small; don't over-invest there before evaporation.
- Track this yearly — a sudden jump in the total often means a new leak.
08
The boundary
How to interpret the result
Measurements, equipment specifications, site conditions and local requirements can change the practical result.
The engine reports invalid inputs and safety warnings beside the result. Resolve those messages before using the estimate.
09
Before acting
What should override this estimate?
- Measured site conditions and current test results
- Product labels and manufacturer specifications
- Qualified-professional advice and applicable local codes
10
Common questions
Frequently asked questions
How much does pool water loss cost per year?
It varies widely with climate, pool size, and whether you use a cover, but evaporation alone can run tens of thousands of gallons a year for an uncovered pool — often well over a hundred dollars in water, plus the chemicals that go with replacing it. Adding splash, backwash, and any leak gives the full annual figure.
What's the biggest source of pool water loss?
Evaporation, in almost every case. For an uncovered pool in a warm or windy climate, it dwarfs splash-out and backwash combined. A leak, if present, can rival or exceed it. This calculator breaks the total into percentages so you can see exactly where your water — and money — is going.
How do I lower my pool's water costs?
Tackle the biggest slice first, which is usually evaporation — a cover cuts it by around 90 percent. Fix any leak promptly, backwash on pressure rather than schedule, and accept that splash-out is mostly unavoidable. Addressing evaporation typically delivers the largest savings by far.
Is losing my whole pool volume in water each year normal?
Replacing a substantial fraction of your volume annually is common for an uncovered pool, mostly through evaporation. Losing well over your full volume each year, though, suggests heavy evaporation plus possibly a leak, and is worth investigating with a bucket test and a cover.
Why track water loss by source?
Because the fix differs for each. Evaporation calls for a cover, a leak calls for repair, backwash calls for better timing, and splash is largely unavoidable. Seeing the breakdown stops you from, say, obsessing over backwash while ignoring the evaporation that's actually costing you most.
How much water does a pool lose in a year?
Often tens of thousands of gallons, mostly to evaporation, for an uncovered pool — varies with climate and cover use.
What costs the most in pool water loss?
Evaporation almost always dominates; a leak can rival it. Splash and backwash are usually minor.
How do I cut pool water costs?
Use a cover to slash evaporation, fix leaks fast, and backwash on pressure — the cover saves most.
Primary sources
Use the result with current guidance.
These official references support safe planning context. Product labels, local requirements and qualified-professional advice take priority over a general calculator estimate.