Slab Leak and High Water Bill: Getting Credits From Your Utility
A slab leak can waste 50 to 500 gallons per day depending on the severity, which adds $50 to $500 or more to a single monthly water bill. If the leak ran undetected for multiple billing cycles, the cumulative overpayment can reach $200 to $1,500. The leak adjustment process exists specifically for situations like this, where a hidden infrastructure failure caused usage the homeowner did not intend and could not reasonably have prevented. The following steps walk you through how to recover as much of that cost as possible.
Gather Your Repair Documentation
The single most important document for your leak adjustment request is the plumber's invoice for the slab leak repair. The utility needs this to confirm that a real leak existed, that it was on your side of the water meter (making you responsible for the usage), and that it has been repaired so the excess usage has stopped.
The invoice should include the date the repair was completed, a description of the work performed (slab leak repair, pipe replacement, reroute, or similar), the plumber's name and license number, and your property address. If the plumber provided a separate detection report, include that as well because it documents the leak type, the pipe material, and the estimated flow rate, all of which help the utility understand the scope of the problem.
If the plumber can include a note on the invoice stating that the leak was concealed beneath the concrete slab and was not visible from the surface, this strengthens your case. Utilities are more generous with adjustments for hidden leaks than for visible leaks (like a running toilet or a dripping faucet) that the homeowner could have noticed and fixed sooner.
Calculate Your Excess Usage
Before contacting the utility, figure out how much extra water the leak consumed. Pull up your billing history online or request copies of the last 12 to 24 months of bills. Identify the billing periods where usage spiked above your normal pattern.
The simplest calculation method is to compare each affected month to the same month in the prior year. For example, if you used 6,000 gallons in March 2025 and 14,000 gallons in March 2026, the excess is approximately 8,000 gallons. Do this for every affected billing period and total the excess gallons. Then multiply by your utility's rate per gallon (or per thousand gallons, which is how most utilities bill) to calculate the dollar amount of excess charges.
Many utilities do this calculation themselves as part of the adjustment process, but arriving at the appointment with your own numbers shows that your request is specific and documented, not a vague complaint about a high bill. It also helps you verify that the utility's calculation is reasonable when they respond.
Note that some utilities bill at tiered rates, meaning higher usage pushes you into more expensive tiers. A slab leak that pushed your usage from Tier 1 into Tier 3 pricing cost you more per gallon than the base rate suggests. Make sure the adjustment accounts for the tiered pricing difference, not just the raw gallon excess.
Contact Your Water Utility
Call or visit your water utility's customer service office and ask specifically about their "leak adjustment" or "high bill adjustment" policy. Almost every municipal water utility in the United States has a formal leak adjustment program, though the name and specific terms vary by jurisdiction.
Questions to ask during this call:
What documentation do you require? Most utilities need the plumber's invoice at minimum. Some also require a completed application form, a copy of the repair receipt, or a letter from the plumber confirming the repair.
What is the filing deadline? Most utilities require the adjustment request within 30 to 90 days of the repair date. Some allow requests within 30 days of the first high bill. Missing the deadline can disqualify your request entirely, so ask this question first.
How many billing periods does the adjustment cover? Some utilities adjust only one billing cycle, while others adjust all billing periods affected by the leak. If you can demonstrate through billing history that the leak was active across multiple months, request adjustment for the full duration.
What percentage of excess charges is credited? Most utilities credit 50% to 100% of the usage above your normal baseline. The 50% approach splits the cost between the utility and the customer. The 100% approach credits the full excess. Some utilities credit 100% of the water charge but not the sewer charge, since the leaked water did not enter the sewer system. Ask about sewer charge adjustments separately if your utility bills for sewer based on water usage.
Is this a one-time or repeating benefit? Most utilities allow one leak adjustment per account per year, or one per account per lifetime. If you have had a previous adjustment for a different leak, mention it upfront to avoid a denial later in the process.
Submit Your Adjustment Request
Complete the utility's leak adjustment application form. Attach the plumber's invoice, your usage comparison showing the excess gallons, and any other documentation the utility requested. Submit the package within the stated deadline.
Most utilities accept applications by mail, in person at their customer service office, or online through their account portal. If you submit by mail, send copies of your documents rather than originals, and consider using certified mail so you have proof of submission date.
In the application or cover letter, state the facts clearly: you had a concealed slab leak that was repaired on a specific date by a licensed plumber, the leak caused abnormally high usage during specific billing periods, and you are requesting an adjustment for the excess usage. Keep the tone factual rather than emotional. Utility employees process these requests routinely and respond best to clear documentation.
If your utility does not have a formal application form, write a brief letter covering the same points: your account number, the repair date, the plumber's name and license number, the billing periods affected, and the excess usage amount. Attach the plumber's invoice and mail it to the customer service address on your bill.
Follow Up and Appeal if Needed
Most utilities process leak adjustments within two to six weeks. If you have not received a response after four weeks, call customer service and ask for a status update. Reference your application date and any confirmation number you received.
If the adjustment is approved, the credit will appear on your next bill or as a direct refund. Review the credit amount to make sure it matches the excess usage calculation. If the credit seems lower than expected, call and ask how the utility calculated the adjustment. Sometimes the calculation excludes certain billing periods or uses a different baseline than what you submitted.
If the adjustment is denied, ask for the specific reason. Common denial reasons include missing documentation (easy to fix by resubmitting with the missing item), filing after the deadline (harder to overcome, but some utilities allow exceptions with a written appeal), or a prior adjustment on the account (the one-time limit). If the denial is based on a technicality rather than the merits of your case, ask about the formal appeal process. Most utilities have a review board or supervisor who can override a front-line denial.
For sewer charge adjustments, you may need to contact your sewer utility separately if it is a different entity than your water provider. The same documentation applies: the water from a slab leak soaked into the ground beneath the foundation and never entered the sewer system, so you should not be charged sewer fees on those gallons.
What the Adjustment Typically Covers
Water charges: The adjustment credits the cost of the excess water above your normal usage baseline. Most utilities use your average usage from the same season in prior years as the baseline. The credit is calculated on the excess gallons at your applicable rate tier.
Sewer charges: If your sewer bill is based on water meter readings (common in many municipalities), you are being charged sewer fees for water that never entered the sewer. Most utilities will adjust the sewer portion as well, either automatically as part of the water adjustment or upon separate request. The sewer adjustment is often the larger dollar amount because sewer rates are typically higher than water rates.
What is not covered: The adjustment does not cover the plumbing repair cost, detection fees, restoration expenses, or any other costs associated with fixing the slab leak. It only covers the excess charges on the water and sewer bill. The plumbing and restoration costs fall under your homeowners insurance or out-of-pocket expenses.
Special Situations
Rental properties: If the slab leak occurred at a rental property, the property owner is typically the account holder and must submit the adjustment request. If the tenant pays the water bill directly, they may be able to submit the request themselves, but they will need the plumber's invoice from the property owner to document the repair.
HOA or multi-unit buildings: In condos and townhouses where the HOA pays the master water bill, the HOA submits the leak adjustment request. Individual unit owners can request that the HOA pursue the adjustment and pass the credit through to the affected units. If the leak was in a common element, the HOA should file automatically as part of their financial management of the repair.
Well water: If your home is on a private well rather than municipal water, there is no water bill to adjust. The cost of a slab leak on a well system is the electricity to run the well pump (typically $10 to $50 per month in increased electric bills) and the repair cost. Contact your electric utility if you can document increased pump run time attributable to the leak, though electric utilities rarely have formal leak adjustment programs comparable to water utilities.
Most water utilities will credit 50% to 100% of the excess charges from a slab leak once you provide a plumber's invoice showing the repair. Submit your adjustment request promptly, include clear documentation, and ask about sewer charge adjustments separately if applicable. The credit can recover hundreds to over a thousand dollars of the overpayment.