Why is my water bill so high?
High bills are usually leaks or usage changes. Use this checklist to find the cause fast.
Direct answer
The #1 cause of unexplained high water bills is a silent leak — most often a running toilet. The average home wastes 9,300+ gallons/year from leaks (EPA). A single running toilet can add $50–200+ to a monthly bill depending on rates.
Diagnostic table: common causes vs. checks
| Cause | How to check | Typical waste |
|---|---|---|
| Running toilet (flapper) | Dye test: food coloring in tank; color in bowl after 15 min | 30–200 gal/day |
| Dripping faucet | Listen/collect drips for 1 min; multiply by 1,440 | 3,000+ gal/year per drip/sec |
| Underground/service leak | Overnight meter test (all water off) | Variable, often large |
| Irrigation / pool | Check timer, valves, autofill; meter test with outdoor isolated | Hundreds of gal/day |
| Rate/tier change or sewer | Compare usage on bill vs prior; check tiers | Can double cost without more gallons |
Worked example
Bill shows 12 CCF this month vs 4 CCF last (1 CCF = 748 gal). Extra 6,000+ gal. Overnight meter test: reading moved 12 gallons with all fixtures off. Dye test positive on master bath toilet. Repair flapper: $12 part. Next bill dropped 8 CCF.
Primary sources
- EPA WaterSense Fix a Leak Week: epa.gov/watersense/fix-leak-week
- EPA Understanding Your Water Bill: epa.gov/watersense/understanding-your-water-bill
- AWWA and local utility leak calculators referenced in EPA materials.
Always verify numbers on your utility bill and site. Rates and policies vary.