Why Is My Water Bill So High?

Opening a water bill that is 30%, 50%, or even 100% higher than normal is alarming — and it almost always has a specific, fixable cause. Here are the most common reasons for a high water bill and how to diagnose each one.

How to Determine If You Have a Leak

Before checking individual fixtures, perform this simple test:

1. Turn off every water-using appliance and fixture in the house (including ice maker, humidifiers, irrigation)
2. Find your water meter and note the reading (including the leak indicator — a small triangle or dial on most digital meters)
3. Wait 30 minutes without using any water
4. Check the meter again — if it has moved, you have a leak

If the meter moves with water off, proceed to identify the source below.

The Most Common Causes

1. Running Toilet — Up to 200 Gallons Per Day

A silent running toilet is the single most common cause of unexplained high water bills in the US. The flapper (the rubber seal between tank and bowl) wears out over time, allowing water to constantly trickle from tank to bowl. You often cannot hear it.

Test: Add a few drops of food coloring to the toilet tank. Do not flush. Wait 15 minutes. If color appears in the bowl, you have a leaking flapper.

Fix: A toilet flapper costs $5–$10 at any hardware store and is a simple DIY replacement. If the fill valve is also faulty, the repair costs $15–$30 in parts. A plumber can replace both for $75–$150.

2. Dripping Faucets — Up to 3,000 Gallons Per Month

A faucet dripping once per second wastes 3,000 gallons per month — that is 36,000 gallons per year. Multiply by multiple leaking faucets and the impact on your bill is substantial. Worn washers, O-rings, or ceramic cartridges are usually the cause.

3. Underground Leaks in Supply Lines

The supply line from the street meter to your home can develop leaks underground that are completely invisible. Signs include wet or soft ground in the yard, green patches following a linear path, or reduced water pressure throughout the house. Professional leak detection is required to locate these.

4. Irrigation System Leaks or Programming Errors

Irrigation systems can develop broken heads, cracked valves, or faulty controller programming that runs zones longer than intended. A broken sprinkler head spraying directly into the ground can waste 25+ gallons per minute. Check all zones manually and inspect for wet spots and controller settings, especially after winter shutoff and spring startup.

5. Hot Water Slab Leak

Hot water supply lines under concrete slabs are subject to corrosion from the inside and abrasion from concrete movement on the outside. A slab leak can waste hundreds of gallons per day, heating water that immediately escapes into the ground — simultaneously raising both your water and gas/electric bill.

Signs include: warm spots on floors, the sound of running water in the floor, or your hot water heater running more frequently than usual.

6. Water Softener or Filtration System Malfunction

Water softeners regenerate regularly using water, but a stuck control valve can cause a softener to run a continuous regeneration cycle. Some filtration systems have bypass valves that fail, sending water continuously to drain. Check these systems if other sources don't explain the usage.

7. Pool Leak

Pools require some water addition for evaporation (typically 1/4 inch per day in summer), but a leaking pool can lose 1–2 inches per day — hundreds of gallons. Perform the bucket test: fill a bucket with pool water, place it on the pool step, and mark both the bucket and pool water lines. After 24 hours, if pool level has dropped more than the bucket, you have a leak.

8. Increased Household Usage

Guests visiting, kids home from school, or new appliances like a high-efficiency washing machine that runs multiple loads can legitimately increase usage. Compare bills to the same month in prior years, not just the previous month.

What to Do About a High Water Bill

• Perform the meter test to confirm there's a leak
• Check all toilets with the food coloring test
• Inspect all visible faucets for drips
• Walk the yard looking for wet ground or green patches
• Check the water softener for continuous operation
• Call a professional if you can't identify the source

Professional leak detection typically costs $150–$500 and is almost always covered by the water savings achieved once the leak is fixed. Call Plumbing Crew USA at (888) 766-7573 to schedule a leak inspection.