Why Is My Water Bill So High? Common Causes & What to Do Next

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Published May 20, 2025 | Updated May 15, 2026

A high water bill is usually caused by one of four things: increased water usage, a hidden plumbing leak, high water pressure creating intermittent water loss, or, in some cases, a defective water meter. In this guide, we’ll explain how to narrow down the cause of a sudden increase in your water bill, how to check for hidden leaks, and when it may be time to call a plumber or contact your local water utility.

Why Is My Water Bill So High?

If your water bill suddenly increases, most homeowners immediately assume they have a major leak somewhere in the house. Sometimes that’s true. But not always.

In our experience, unusually high water bills usually fall into one of four categories:

1. You’ve been using more water than you realized
2. There’s a leak somewhere outside on your main water supply
3. There’s a leak somewhere inside the home
4. The water meter itself may be reading incorrectly

The good news is that most of these situations can usually be narrowed down fairly quickly once you know what to look for.

1. Have You Been Using More Water Than You Realized?

Sometimes the answer is simpler than homeowners expect.

Water usage often changes seasonally without people noticing it right away. A few longer showers, extra laundry, watering the lawn, filling a pool, kids home from college, or out-of-town guests staying for a week can add up surprisingly fast.

Spring and summer are especially common times for water bills to rise because irrigation systems begin running again and outdoor water usage increases.

Even small changes in daily habits can create a noticeable difference on your monthly bill, especially in areas that use tiered water pricing where the cost per gallon increases after certain usage thresholds are reached.

Before assuming there’s a leak, it’s worth honestly asking whether your household has simply been using more water lately.

2. A Leak Outside on the Main Water Line

If your water usage habits haven’t changed, the next possibility is often a leak on your main water supply line, somewhere between the water meter and your home.

Your main water line runs underground, which means leaks can waste a tremendous amount of water without creating obvious signs inside the house.

Some homeowners notice:

• Wet spots in the yard
• Soggy areas near the driveway or sidewalk
• Areas of unusually green grass
• A sudden drop in water pressure
• Water pooling near the meter

But in many cases, there are no visible symptoms at all besides the higher water bill.

If you believe the problem may be outside underground, our water line repair team can help diagnose and locate the issue.

3. A Leak Somewhere Inside the Home

Interior plumbing leaks are one of the most common causes of high water bills.

And not all leaks look dramatic.

Many homeowners imagine a plumbing leak as water pouring through the ceiling, but some of the worst water waste comes from slow, hidden leaks that continue 24 hours a day.

Running Toilets Are Extremely Common

A running toilet is essentially a leak from the toilet tank into the bowl.

If your toilet won’t stop running, it can waste hundreds of gallons of water per day without drawing much attention.

Common causes include:

• Worn flappers
• Fill valve problems
• Misadjusted floats
• Loose or deteriorated components inside the tank

A quick test is to place food coloring in the tank. If color appears in the bowl without flushing, the toilet is leaking.

Slab Leaks

Slab leaks occur underneath the concrete foundation of the home and can sometimes go unnoticed for a long time.

Common signs include:

• Warm spots on floors
• Damp flooring
• Buckling hardwood floors
• Mold or mildew odors
• The sound of running water when no fixtures are on
• Low water pressure

These leaks can waste a tremendous amount of water before they become visible.

Leaks Inside Walls

Leaks inside walls are another common issue.

Sometimes homeowners notice discoloration, bubbling paint, or soft drywall. Other times, the leak is small enough that the only symptom is a higher water bill.

Even small drips behind walls can waste a surprising amount of water over time.

Dripping Faucets Add Up Faster Than Most People Realize

Even a slow drip can waste thousands of gallons of water over time.

If you want to estimate how much water may be going down the drain, try our faucet drip calculator.

High Water Pressure Can Cause Intermittent Water Loss

High water pressure can quietly contribute to water loss throughout a home.

Pressure that is too high can worsen small leaks, force water through weak seals, and cause toilets or faucets to slowly seep water around the clock.

In some homes, pressure fluctuations happen mostly at night when fewer people in the neighborhood are using water. During these periods, pressure can spike significantly higher than normal.

We sometimes see situations where the temperature and pressure relief valve on the water heater intermittently opens because of excessive pressure. Since this discharge often drains away unnoticed, homeowners may receive a high water bill without ever seeing visible water anywhere in the house.

In situations like this, a 24-hour pressure test may be the best way to determine whether excessive pressure is contributing to the problem.

How to Check for a Plumbing Leak

One of the easiest ways to determine whether you may have a hidden plumbing leak is by checking your water meter.

This simple test can help determine whether water is flowing somewhere in the home even when nothing is actively being used.

Step 1: Turn Off All Water Usage

Make sure nobody is using water inside or outside the home.

Turn off or avoid using:

• Faucets
• Showers
• Washing machines
• Dishwashers
• Ice makers
• Irrigation systems
• Hose bibs

Even a small amount of active water usage can affect the test.

Step 2: Locate Your Water Meter

Most water meters are located near the curb, sidewalk, or street in a covered utility box.

Once you find the meter, watch it carefully for several minutes.

If the meter continues moving while all water is off, water is flowing somewhere in the plumbing system.

Step 3: Narrow Down Where the Leak May Be

If the meter is moving, the next step is to turn off the main water shut off valve to the house.

Then check the meter again.

• If the meter stops moving, the leak is likely somewhere inside the home
• If the meter continues moving, the leak is more likely between the meter and the house underground in the main water line

This test will not always pinpoint the exact problem, but it can often help narrow down whether the issue is inside the house or outside underground.

4. Sometimes the Water Meter Is Wrong

This is much less common than plumbing leaks, but it does happen.

If a plumber has thoroughly checked the home and confirmed there is no plumbing leak, it may be worth contacting your local water utility to discuss the possibility of a defective meter.

We have occasionally seen situations where meters were reading incorrectly or where utility-side issues contributed to unexpectedly high bills.

In many areas, the utility provider can perform additional testing or investigate the meter further if requested.

Understanding Your Water Bill

Many homeowners are surprised to learn that water bills are not always charged at a flat rate.

Many utilities use tiered pricing structures where the cost per gallon increases as usage rises. Sewer and stormwater fees are also often tied to water consumption.

This means that even a moderate increase in water usage can sometimes create a disproportionately large increase in the total bill.

Comparing your current bill to the same month last year is often more useful than comparing it to the previous month, since seasonal usage changes can affect water consumption significantly.

When you understand your water bill and how it handles utility billing, tiers, sewer charges, and average household usage, you can more easily compare bills to determine what changed.

Can You Get a Credit for a High Water Bill?

Many counties and water authorities offer leak adjustment programs if a plumbing leak caused the increase.

In most cases, you’ll need:

• Documentation showing the leak was repaired
• A plumber’s invoice
• A completed adjustment request submitted within a certain timeframe

The amount of the adjustment varies depending on the utility provider, but it can sometimes significantly reduce the impact of a leak-related bill spike.

At Aaron Plumbing, we provide detailed invoices and documentation to help homeowners through this process when applicable.

Aaron Services Can Help

If your water bill suddenly increased and you’re not sure why, our experienced plumbers can help identify the cause.

Our general plumbing services team can:

• Perform leak detection
• Test water pressure
• Diagnose running toilets and hidden plumbing leaks
• Inspect water lines
• Help determine whether the issue may involve the utility meter

Our team focuses on clear explanations and honest recommendations so homeowners can confidently understand what’s happening and what their options are.

If you think your home may have a hidden plumbing leak, it’s usually best to investigate sooner rather than later before additional water loss or damage occurs.

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