Q&A for How to Find a Water Leak in Your House

That is probably one of the most difficult leaks to detect. Every meter has what's called a leak dial. If your meter is spinning and there's nothing being used in the house, then you either have a running toilet or you have a leak under the slab. Determining where that leak is exactly can be tricky, and I recommend calling a professional for help.

It sounds like the line between the meter and the main shutoff valve.

It's probably the main cold water supply or the branch of supply that has the leak. If you have that volume of water running through your pipes, it's underground, under the slab or flooring. Turn off your shutoff at the water heater to determine if it's on the hot or cold. If it's on the hot, walk around with a laser thermometer to try and find the source of leak. To pin point cold water unfortunately, you need a listening device.

The county and the city water department generally are only responsible for the meter at the water main. Anything between the main and the house, including the water supply pipe, is the responsibility of the home owner. Contact a plumber or contractor in your area.

No, but if you don't you could end up digging again to repair any new leaks. If your pipes are getting to the point that they are breaking down, then it could happen anywhere, so you have the choice of either doing only what is broken or the whole line. If you call a plumber, they will tell you the whole line (as explained), but if you do it yourself it will be cheaper. The only thing is that you won't know when it will happen again.

Most municipalities will replace the meter if you make a request, start there.

Water flows from high to low, follow the traces back toward the source. For leaks associated with pipes, look for joints, elbows, and connections as these are the weak points (poor seals or corrosion begins here). Know the different piping materials you have as they all fail or get damaged differently. For roof leaks, water spots on ceilings and walls will need to be traced back to the source as a hole (sometimes very tiny) allows water to weep in and flow down the roof supports.

There could be a rust spot (easily turns into a hole) or an improper seal around the bathtub drain that is underneath the tub connecting to the drain pipe itself. It will have to be sealed.

You would likely have to dig 2–5 feet before finding any water, so you should probably call a leak detection or plumber to help you.

First, check your water meter to see if you have an underground water leak. If the flow indicator (small red triangle or snow flake) is rotating, you have a leak. For this I would call a reputable leak detection company or plumber. If there is no leak indicated on the flow indicator, you will want to call the water company and have them check the system. If you have a pressure regulator on your main, it may need to be adjusted or replaced.

Maybe there is a leak. You should immediately check and you should put water sensors in your home.

No.

We had that happen in a house from the 50's. They had to find the main drain unit and found that the vent pipe (from junction out to roof) had become dislodged. Because we lived in a very sandy soil area, the water was going into the junction to drain, but was also adding sand that eventually clogged the pipes and the water was backing up under the house. It was built on a slab foundation. You may want to call a professional to see if yours is something similar.

Is there an irrigation line or sprinkler valve outside the window that could be the source? I had this issue and it was a slowly leaking sprinkler valve that saturated the soil in the planter outside the window. After it was fixed and the soil dried the smell went away.

Cut open the wall/ceiling around that area (or get permission to do so if you aren't the homeowner) and try to expose water and drain lines above that area. Water follows the path of least resistance, so start above the wettest part.

If the flow is constant, it's likely a pipe leak. If it is not constant, it could be a drain line or even condensation.

It could be your shower pan needs replacing, or just the drain from the shower pan to the drain under your shower is leaking. The shower pan is (typically) a metal shallow tub underneath the tiled floor of a shower that eventually needs to be replaced. This is typically done by ripping out the shower floor, putting in a new pan, and re-tiling. However, some companies will just go over the existing shower with new fiberglass floor and walls (less time consuming, but often not as attractive as new tile). Be sure to check if you just need a new connection (or new seal) at the base of the shower pan (under the tile) to the drain line. That's far less expensive or disruptive to fix.

If the meter indicator is not spinning, then the source of water is separate - groundwater, or a neighbor's water line. The municipal water department can test the water to see if it is groundwater (no treatment chemicals will be present).

Highly unlikely. Those sounds are probably from other fixtures nearby reverberating through the system.

If the shutoff valve at the house is closed (or at least turned off as far as it will go) and flow is still audible, that may indicate that the valve does not fully close.

Replace all tank hardware and washers and seals. Read directions and check that the washers are installed right. If that does not work, you may have a small crack in the tank.

Most leaks occur without surfacing. Many that do "show" will surface a distance away from where the leak is. In most areas of the USA, the water lines are run 2-4 feet below the surface, depending on the temperature extremes. Call a reputable leak detection company. The price for this varies from region to region. In Cincinnati, for example, the going rate is $350. The process is somewhat involved, but includes adding nitrogen or compressed air to your system, then listening to your line to find the leak. Then, they'll double check those results by adding helium and tracing it with an electronic helium detector. If you have an interior leak, the process is more involved as you are working with a concrete slab.

Start by closely inspecting every tap, faucet, and exposed pipe in the general vicinity of the sound. If that doesn't it up, it may be hidden behind the walls, floor, or ceiling, in which case you'll need to hire a plumber and/or contractor with plumbing experience to pinpoint the source of the leak without unnecessary damage to the surrounding structures.

You'll need to have a water service specialist come in to dig up and replace the loose or ruptured section of pipe. This type of repair can be somewhat expensive, but it's much less costly than leaving the problem unaddressed.

"Phantom" wet spots or discoloration is often a sign that the leak is emanating from a nearby pipe. If there's water dripping from the ceiling, check for leaks in all major fixtures on the floor above. If it appears to be coming through the wall, it means the leak is either in an adjacent room or spreading from a plumbing fixture behind the wall in an abnormal way.

Absolutely. Without a dependable leak indicator, you have no way of knowing whether or not you have a leak in your water lines, and no starting point for determining whether the leak is located inside your home or somewhere in the external lines running between it and the meter.

It's tough to say without seeing the area you're talking about, but if it's not dripping from the ceiling, the source of the leak is probably somewhere behind the wall in the area around the window. It's also possible that it's on the floor immediately below, and that the wet spot is the result of water wicking and spreading up through the wall and floor.

Consider having a plumber come out and run a camera through those lines.