High Water Bill
Updated February 20, 2026
Unexplained spike in your water bill usually means a hidden leak, running toilet, or dripping fixture. Finding and fixing it saves hundreds per year.
Overview
Water bill jumped and you cannot explain it? Something is using water you do not know about. A running toilet wastes 200+ gallons per day. A dripping faucet wastes 3,000+ gallons per year. A hidden slab leak or underground pipe leak wastes even more and you never see it. Diagnosing starts with the water meter: shut everything off, check if the meter is still moving. If it is, you have a leak. Then work through the house systematically -- toilets first (most common), then faucets, then supply lines, then outdoor irrigation, then hidden leaks.
Symptoms
- Water bill significantly higher than previous months with no change in usage
- Meter dial or flow indicator spinning when all fixtures are off
- Sound of running water when nothing is on -- check toilets, supply lines, water heater
- Wet spots in the yard, driveway, or foundation with no obvious source
- Warm spot on the floor (possible hot water slab leak)
- Musty smell or mold growth in areas near plumbing
Common Causes
- Running toilet -- most common cause. Worn flapper leaks water from tank to bowl continuously. Can waste 200+ gallons per day. Often silent.
- Dripping faucet -- seems minor but adds up. One drip per second = 3,000+ gallons per year. Multiple dripping faucets multiply the waste.
- Leaking supply line or shut-off valve -- slow drip behind a wall, under a cabinet, or at the water heater. May not be visible until damage appears.
- Outdoor irrigation leak -- broken sprinkler head, cracked irrigation line, or stuck valve running water into the ground. Easy to miss if the system runs overnight.
- Slab leak or underground pipe leak -- pipe under the foundation or in the yard leaking into the ground. No visible sign except the water bill and possibly warm/wet spots.
- Faulty water softener or treatment system -- stuck in regeneration cycle, backwashing continuously, or bypass valve leaking.
What You'll Need
How to Fix It
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Check the Water Meter
Turn off every water-using fixture and appliance in the house. Dishwasher, washing machine, ice maker, irrigation -- everything. Find the water meter (usually near the street in a ground box). Look at the flow indicator (small triangle or dial). If it is moving with everything off, you have a leak somewhere. Note the meter reading, wait 2 hours without using any water, check again. Numbers changed? Confirmed leak.
Tip: The meter test tells you IF there is a leak, not WHERE. But it is the essential first step. If the meter is not moving, the high bill may be from increased usage you forgot about (filling a pool, watering new sod, house guests). -
Check All Toilets First
Toilets are the number one cause of high water bills. Add food coloring to each toilet tank. Wait 15 minutes without flushing. Color in the bowl? The flapper is leaking. Check every toilet in the house -- a silent leak in a guest bathroom can run for months unnoticed. Also listen: a toilet that cycles on briefly every few minutes (phantom flushing) has a slow flapper leak.
Tip: A worn flapper costs $3-8 to replace and takes 5 minutes. It is the cheapest fix for the biggest water waste. Check every toilet, not just the ones you use daily. -
Inspect All Faucets and Fixtures
Walk through the house and check every faucet, shower head, and hose bib for drips. A drip every few seconds seems minor but wastes thousands of gallons per year. Check under sinks for supply line drips -- open cabinet doors and feel the connections. Check the water heater T&P valve discharge pipe for dripping.
Tip: Check hose bibs outside too. A dripping hose bib that you never look at wastes just as much as an indoor faucet. -
Check Outdoor Irrigation
Run each irrigation zone manually and walk the system. Look for broken heads (geysers), cracked pipes (soggy spots in the yard), and stuck valves (zones that run when they should be off). Check the irrigation timer for incorrect programming -- a zone running daily instead of weekly multiplies water use by 7x. Disconnect the irrigation system from the main line and recheck the meter.
Tip: If the meter stops moving after disconnecting irrigation, the leak is in the irrigation system. If it keeps moving, the leak is inside the house or in the main supply line. -
Look for Hidden Leaks
If the meter is moving but you cannot find a visible leak: check for warm or wet spots on floors (slab leak). Listen at walls near plumbing runs for the sound of running water. Check the water heater area, washing machine connections, and any accessible plumbing in the basement or crawl space. Look for water stains on ceilings below bathrooms.
Tip: A hot water slab leak often shows as a warm spot on the floor and an unusually high gas or electric bill (the water heater is working overtime to replace the lost hot water). -
Call for Professional Leak Detection
If the meter confirms a leak but you cannot find it, call a plumber with leak detection equipment. They use acoustic listening devices, thermal cameras, and tracer gas to locate leaks behind walls, under slabs, and underground without tearing anything apart. The diagnostic fee ($150-300) is worth it to pinpoint the exact location before any demolition.
Tip: Some water utilities offer free leak detection or will credit your bill if you can show a repair was made within a certain timeframe. Call your utility first.
When to Call a Pro
Call a plumber if the meter confirms a leak but you cannot find it, if you suspect a slab leak or underground pipe leak, if the leak is behind a wall or under the floor, or if you need professional leak detection equipment. Also call if your water utility is threatening penalties for excessive usage and you need the leak found and fixed urgently.
Prevention Tips
- Check the water meter monthly. A 2-minute check catches leaks before they run up your bill for weeks.
- Dye-test all toilets every 6 months. Replace flappers every 3-5 years proactively.
- Fix dripping faucets immediately. A slow drip is 3,000+ gallons per year.
- Walk outdoor irrigation monthly during the watering season. Broken heads and stuck valves waste enormous amounts.
- Know your baseline water usage. If your bill has a graph, watch for sudden jumps. Most utilities also offer high-usage alerts.
- Install a whole-house water monitor ($150-300) that tracks usage in real time and alerts you to unusual flow patterns. Catches leaks within hours instead of months.