Is hot water seeping under your concrete slab? Then better fix it right away! Otherwise, you’ll end up with a damaged home, not to mention higher bills.

If you don’t know what to do, you’re in luck! Here is a simple guide to help you understand and address water leaks under slabs. From finding the source of the leak to a few troubleshooting tips, everything you need is down below!

How to Find a Hot Water Leak Under a Slab

When you discover a hot water leak under a slab, it’s essential to locate it promptly to prevent further damage. Doing that can be challenging. So to make your life easier, here are a few expert tips to follow:

Check Your Water Bills

Browse through your most recent water bills and look for sudden spikes in usage. If you spot any, then that could indicate that there’s something wrong with your plumbing. It can be useful to check your year-on-year usage. Don’t just look at a single month to determine an issue, check to see what your usage was like for the same month last year as well.

Watch Out for Hotspots

Walk barefoot around your home, especially on tiled or concrete floors. If you notice warm spots, it could indicate a hot water leak beneath the slab.

Listen for Water Noises

Turn off all appliances that use water and find a quiet time in your home. Listen carefully near floors and walls for any sound of running water. A leak might be present if you hear continuous water movement.

Use a Moisture Meter

A moisture meter designed for concrete surfaces can help you identify areas with higher moisture levels. Concentrated moisture points can point to a potential leak.

Look for Mould and Mildew

Keep an eye out for mould or mildew growth on your floors or walls. Excess moisture from a leak can create the perfect conditions for these to flourish.

Inspect Foundation Cracks

Cracks in the foundation or the slab can indicate shifting caused by water leakage. If you notice new or expanding cracks, it’s worth investigating further.

Use an Infrared Camera

Infrared cameras can detect temperature variations on surfaces. A hot water leak can cause a temperature difference, which an infrared camera can help visualise.

Try a Listening Device

Alternatively, acoustic leak detection devices can pick up sounds from water escaping through a small opening. Through these tools, you’ll be able to pinpoint the source of the leak more precisely.

Call a Professional

If you still can’t find the leak even after trying the previous tips above, phone your trusted professional plumber. With their tools and expertise, they can quickly locate even the most hard-to-find leaks within your house.

How to Repair a Hot Water Leak Under a Slab

Once you find the source of the leaks, you need to act quickly to prevent further damage and restore your plumbing back to normal. Here are the steps you need to promptly repair leaks under your concrete slab:

Step 1

Turn off your water supply. For good measure, switch off nearby electrical or gas power sources, too. Then make sure the work area is adequately ventilated.

Step 2

Drain your hot water system. Open the faucets and valves to release the water inside the pipes. This will also help remove any pressure inside the system.

Step 3

Clear the area above the concrete slab where the leak is located. Remove anything that obstructs access to the damaged pipes. Depending on the situation, you might need to cut through the slab.

Step 4

Repair or replace the damaged pipes. Use appropriate tools to remove the old lines from the floor. Then measure and cut the replacements. Make sure they have the same specs as the old ones. Gently connect it to the system with fittings.

Step 5

Make sure the new pipes are correctly installed and secure to prevent future leaks. Use soldering or compression connectors to ensure a tight fit. A study by Mohamed A. Safan and his colleagues also suggests using polyurethane resin injection.

Step 6

Test for other leaks by turning your water supply back on. Make sure you do this gradually rather than suddenly, as doing the latter might damage your system again. Check the recently repaired section for any signs of leaks. And monitor the circulation of the hot water to assess your system’s performance.

Step 7

Fix your excavated floor by backfilling it with suitable material or repositioning the slab you removed earlier. Just do the job right to restore the area to its original state.

Step 8

Check the pipes near the system for wear and tear. If you spot any issues, fix them immediately to prevent future leaks.

Alternative Techniques to Repair Slab Leaks

The steps above are great when excavating the slab to get to the leaks. If you don’t want to do that, then you can try the alternate techniques below:

Pipe Rerouting

This involves bypassing the damaged section altogether by redirecting the hot water line away from the slab. While less invasive, this method sometimes requires extensive plumbing work, making it more costly. In fact, Thissoldhouse noted that it can cost between $1,500 and $15,000, especially if multiple lines are damaged.

Tunnelling Beneath the Slab

This technique involves creating a tunnel underneath the foundation to access and repair the hot water leak. This can be the best option in case the other methods are not feasible (due to the layout or construction of the property). However, bear in mind that it’s a labour-intensive process, not to mention a pricey one.

Trenchless Pipe Repair

This method involves using specialized tools and techniques to repair or replace the damaged pipe without significant excavation. Trenchless pipe repair is a quick and cost-effective solution. However, it may only be suitable for some leaks or slab configurations.

Cost of Repairing a Hot Water Leak Under a Slab

In Australia, the cost to repair slab leaks can be as low as $840 or as high as $5,800 (sometimes more). This might not include leak detection services, which can fetch around $200 to $530.

Factors Affecting The Cost to Repair Slab Leaks

Location of Leak

The leak’s location will influence the repair’s difficulty, thus affecting the overall cost. The closer the leak is to the surface, the cheaper it could be. But you might spend more if the problem lies deep under the slab.

Pipe Material

The type of pipe you use can also affect repair costs due to their respective prices and labour fees. Different types of tubes include PVC, PEX, and copper, among others.

Extent of Damage

The number of leaks and the severity of the damage will play a role in repair costs. If there’s more than one leak or the system’s problem is too complex, you’ll end up with a bigger tab to pay.

Slab Removal

Sometimes, repairing leaks involve removing the flooring materials covering your pipes. This can further add to your labour and restoration expenses.

Local Labour Rates

The labour cost to repair slab leaks will ultimately depend on the provider. So make sure you pick the expert near your area and compare rates from different companies.

Sealing and Insulation

Fixing slab leaks allows you to enhance your plumbing system’s performance via sealing and insulation. If you want to give it a go, then consider these tips:

  • Add Pipe Insulation. This helps reduce condensation, regulate water temperature, and prevent future leaks.
  • Use Quality Sealants. This helps ensure water-tight connections and minimise leaks at the fittings and joints.
  • Use Expansion Joints. This will help your plumbing system cope with movement caused by temperature changes, minimising leaks and stress.
  • Add Anti-Corrosion Coating. If you’re using metal pipes, apply anti-corrosion coatings to prevent rusting and extend the overall lifespan.
  • Do a Pressure Test. After repairing the leak, conduct a thorough pressure test to check the system’s performance and see if other leaks are missed.

Safety Precautions

Repairing slab leaks can sometimes be risky. So to prevent accidents, injuries, or further damage, follow these safety precautions:

  • Turn Off the Water and Power. As mentioned above, you need to switch off your water, electricity, and gas before getting started.
  • Wear Protective Gear. This includes gloves, safety goggles, respiratory masks, and other personal protective equipment (PPE).
  • Use a Gas Detector. If the leak is near gas lines, keep a gas detector on hand to avoid toxic fumes.
  • Ensure Proper Lighting. Make sure there’s adequate lighting in the work area so you can see everything clearly.
  • Ensure Proper Ventilation. Again, as mentioned above, make sure the work area is well-ventilated to prevent hazardous gases from causing trouble.

Troubleshooting Tips

Lastly, properly troubleshooting slab leaks is vital to effectively diagnose and address the problem. Here are a couple of great tips to follow on specific issues:

Insufficient Water Flow

If you’re experiencing low water flow, it could be due to leaks, blockage, sediment, or corrosion. Test your faucets and other fixtures. Compare the water pressure coming from each fixture. This will help you pinpoint where the issue is.

Uneven Water Temperature

Inconsistent water temperature is likely due to problems with your water heater or mixing valve. To troubleshoot this issue, start with your heater’s thermostat settings. Make sure it’s properly adjusted. If the problem persists, call your trusted plumber.

Prolonged Repair Time

Sometimes it takes longer to repair slab leaks. This could be due to multiple factors, from difficult-to-reach spots to complexities within the pipe system. If you don’t have the time or patience to deal with these issues, consider seeking professional assistance.

Reoccurring Leaks

Reoccurring leaks can result from underlying issues like corroded pipes or excessive water pressure. It’s essential to address these root causes before embarking on any water leak repairs. Otherwise, you’ll deal with new leaks even after you fix previous ones.

Water Flow Interruptions

If you’re experiencing water flow interruptions, there might be issues with your main water line or valves. So start checking those areas to troubleshoot the problem. If the problem is too complex for you to handle, feel free to call your trusted plumber.