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Slab Leak Guide

Is a Slab Leak Causing Your High Water Bill?

A sudden spike in your water bill often means a hidden slab leak. You can check with a simple water-meter test, and repair options start under $500.

Reviewed by SlabSleuth Team9 min read
Check Your Bill

The short answer

A sudden, unexplained spike in your water bill is a classic slab-leak sign. Turn off all water and watch your meter for 15 minutes. If it moves, you likely have a leak under the slab. Repairs typically cost $630-$4,400, depending on the fix.

Key takeaways

  • Check your water meter: The quickest way to confirm a slab leak is the 15-minute meter test.
  • Don't ignore a high bill: Even a small slab leak can waste thousands of gallons and cause structural damage.
  • Repair costs vary widely: Spot repairs start around $150, but complex reroutes can hit $15,000.
  • Insurance rarely covers the leak: Standard policies only pay if the leak was caused by a covered event, not wear and tear.

A high water bill is often the first red flag for a slab leak. Before you panic, you can run a simple DIY test to narrow down the cause. This guide walks you through checking for a slab leak, understanding the costs, and deciding when to call a pro.

What does a slab leak do to your water bill?

A slab leak is a continuous water loss, so it shows up fast on your bill. Even a small leak can waste thousands of gallons each month.

  • A slab leak runs continuously, so your water bill can jump unexpectedly without a change in your habits.
  • Compare your bill to the same month last year: a 20-30% increase without explanation often points to a leak.
  • Check for other signs like warm spots on the floor, the sound of running water, or low water pressure.
  • Mold or mildew in a normally dry area can also signal a hidden leak.

Learn more about slab leak signs and detection.

If you see these signs alongside a high bill, it's likely a slab leak.Checklist of 5: Water meter moves with everything off; Sound of running water when no taps are open; Warm or damp spots on floor; Unexplained mold or mildew; Low water pressure.If you see these signs alongside a highbill, it's likely a slab leak.Water meter moves with everything offSound of running water when no taps are openWarm or damp spots on floorUnexplained mold or mildewLow water pressure

How do I check if my high water bill is from a slab leak?

The water-meter test is the go-to DIY check. It takes 15 minutes and no tools.

  • Turn off all water-using appliances and fixtures, including ice makers and irrigation systems.
  • Locate your water meter and record the reading.
  • Wait at least 15 minutes without using any water; then check the meter again.
  • If the dial has moved, you have a leak somewhere on your property.
  • To rule out a toilet or faucet leak, shut off individual supply valves and repeat the test. If the meter still moves, the leak is likely underground or in the slab.

Use our Slab Leak Triage tool for step-by-step instructions.

The 15-minute water-meter test confirms a slab leak.Timeline. 1: Shut off all water; 2: Record meter reading; 3: Wait 15 minutes, no water use; 4: Check if meter dial moved; 5: Meter moved? Slab leak likely.The 15-minute water-meter test confirms aslab leak.1Shut off all water2Record meter reading3Wait 15 minutes, no water use4Check if meter dial moved5Meter moved? Slab leak likely

How much does a slab leak repair cost?

Repair costs depend on the leak's location and the fix method. Below are typical ranges as of 2026. Costs vary by region, access, and contractor. Ranges on this page are compiled from the sources on our methodology page. Get at least two local quotes.

  • Detection: $150 to $400.
  • Spot repair: $150 to $2,000 (a burst-pipe spot repair can reach $3,000).
  • Epoxy lining: $500 to $3,500 flat, or $80 to $250 per linear foot.
  • Reroute: $600 to $7,500, extensive up to $15,000.
  • All-in repair: typically $630 to $4,400 (average about $2,280).

Estimate your costs with our Slab Leak Cost Calculator.

A full slab leak repair typically falls between $630 and $4,400.Bar chart. Detection only: 150; Spot repair (low): 150; Epoxy lining: 500; Reroute (partial): 600; All-in typical low: 630.A full slab leak repair typically fallsbetween $630 and $4,400.Detection only150Spot repair (low)150Epoxy lining500Reroute (partial)600All-in typical low630

What mistakes do homeowners make with a high water bill?

A high bill can trigger panic, but rushing into the wrong fix wastes time and money.

  • Ignoring a single high bill: even if it drops next month, the leak is still active.
  • Paying the bill without investigating: the leak will only worsen and cost more later.
  • Assuming it's a toilet or faucet leak without testing: do the meter test before dismissing a slab leak.
  • Calling a plumber before doing the water-meter test: the test saves you a service call fee.
  • Expecting insurance to pay for the repair: standard policies rarely cover the leak itself, only sudden and accidental damage; confirm with your carrier.
The biggest mistake is overlooking the simple 15-minute meter test.5 fact cards: Ignoring the bill, Paying the bill without investigating, Skipping the water-meter test, Calling a plumber without the test, Assuming insurance will pay.The biggest mistake is overlooking thesimple 15-minute meter test.Ignoring the billThe leak continues, wasting water anddamaging your slab.Paying the bill withoutinvestigatingYou're still losing water and moneyevery day.Skipping the water-meter testThis free test can confirm a slab leakin minutes.Calling a plumber without thetestYou may pay a service fee just forthem to do the same check.Assuming insurance will payMost policies exclude slow leaks,confirm with your carrier.

Slab leak vs. other causes: why is my water bill so high?

A slab leak is just one possibility. First rule out cheaper and more common culprits.

  • Running toilets are the most common cause, they can waste 200 gallons a day. Check by listening or adding food coloring to the tank.
  • Irrigation leaks show up as soft spots in the yard or wet patches when the system is off.
  • Yard pipe leaks might be visible but sometimes are underground outside the slab; they'll still show up on the meter.
  • A slab leak is inside the foundation: the meter test with the main valve helps isolate, if the meter stops when you shut off the house valve, the leak is indoors, making a slab leak more likely.

Try our Slab Leak Triage tool to narrow it down.

Use the water-meter test to narrow down the cause.4 fact cards: Running toilet, Irrigation leak, Yard pipe leak, Slab leak.Use the water-meter test to narrow downthe cause.Running toiletCheck by adding food coloring to thetank, often a $10 fix.Irrigation leakLook for wet spots or broken sprinklerheads.Yard pipe leakMay surface as soggy ground, can becostly to dig.Slab leakNo visible water, meter moves withhouse valve open.

When should I call a plumber for a slab leak?

After the meter test indicates a slab leak, it's time for a pro. Breaking into the slab is not a DIY job.

  • If the water-meter test shows a leak and you've ruled out accessible fixtures, call a licensed plumber with slab leak detection equipment.
  • If you hear water running inside walls or floors but can't pinpoint it, pros use acoustic listening devices.
  • If your water bill has doubled or tripled suddenly, the leak is likely severe and needs urgent attention.
  • Do not attempt to break into the slab yourself: this is dangerous and can worsen the damage.
  • Get at least two quotes for detection and repair; costs vary widely, and some companies offer free inspections. Use our Repair Method Finder to compare approaches.
These signs mean it's time to call a licensed plumber.4 fact cards: Meter test confirms a leak, Unexplained water sound, Spike in water bill > 50%, Warm floor spots.These signs mean it's time to call alicensed plumber.Meter test confirms a leakYou've ruled out toilets and faucets.Unexplained water soundRunning water noise with no visiblesource.Spike in water bill > 50%A major leak is wasting hundreds ofgallons daily.Warm floor spotsHot-water line leak under the slab.

Questions this page answers

Can a slab leak cause a high water bill?

Yes, it's one of the most common causes. Even a small leak can waste thousands of gallons a month, leading to a sudden spike in your bill. If your usage jumps with no explanation, do a water-meter test.

How much water does a slab leak waste?

It depends on the leak size, but a leak the size of a pencil lead can waste over 6,000 gallons a month. Your water bill will often double or triple from normal.

Will homeowners insurance cover my high water bill from a slab leak?

Standard HO-3 policies may cover damage from sudden and accidental events, but they rarely cover the leak repair itself or the excess water usage. You might have coverage for access and restoration if the leak is from a covered peril. Always confirm with your carrier.

Can I check for a slab leak without calling a plumber?

Yes, the water-meter test is a simple DIY check. Turn off all water, record the meter reading, wait 15 minutes, and recheck. If the dial moved, you have a leak.

How much does it cost to fix a slab leak?

All-in repair costs typically range from $630 to $4,400, as of 2026. Simple spot repairs can be as low as $150, while extensive reroutes or repipes can exceed $15,000.

Should I pay the high water bill first or fix the leak?

Contact your water utility immediately; many offer a one-time leak adjustment once you prove the repair. Fix the leak first to stop ongoing waste, then provide the repair receipt to your utility.

Can a high water bill be from something other than a slab leak?

Absolutely. Running toilets, irrigation leaks, and yard pipe breaks are more common. Rule these out with the meter test and by checking fixtures before assuming a slab leak.

How long does it take to fix a slab leak?

Detection usually takes an hour, and most repairs can be completed in one to two days, depending on the method. Spot repairs are quicker, while reroutes may take longer.

A high water bill is often the first sign of a slab leak. Use the 15-minute water-meter test from our Slab Leak Triage tool to confirm it, then explore repair costs with our Repair Method Finder. Remember, repair costs average around $2,280, but get local quotes to nail down your number.