How to Detect Water Leaks in Walls

Water pipe malfunctions are often the cause of leaks, but this issue can also occur when rainwater seeps into the walls or when the foundation of the house cracks and opens up. Long-term water infiltration can damage the internal structure of the walls and lead to serious mold problems. You can spot water leaks by observing visible signs of water damage, such as peeling paint or wallpaper, or patches of walls that have discoloration or stains. A musty smell inside the house could also be a sign of water penetration. To pinpoint the exact location of the leak, you can use a water meter or even cut through the wall.

Look for water puddles near the walls. This is the simplest way to detect if water is leaking into the walls. You can be certain there's a leak if you notice carpets getting suspiciously wet or spots on the floor that are consistently damp in a particular area of the house.

• You'll usually find wet floors near areas where water-using appliances are located (washing machine, dishwasher) or in bathrooms near sinks, toilets, or showers.

Look for discoloration on the walls. If there is water leaking behind the walls, the surface of the wall will gradually change color. Search for areas of the wall that appear slightly faded or lighter than the surrounding area, whether it's wallpapered, drywall, or even wooden paneling.

• The discolored patches usually do not have a defined shape.

Observe changes in the texture of the wall surface. Walls with water leaks behind them often show signs of bulging, similar to bubbles. Paint or wallpaper will wrinkle or sag, forming tears or blisters when the water damages their normal structure.

• Drywall with trapped water will sag. Small bubbles or sections of the wall bending downward can also indicate the presence of water inside the walls.
• Heavily waterlogged walls may even bend outward. Eventually, drywall will sag due to the weight of the water trapped within it.

Pay attention to signs of mold. If a leak persists for a while, mold may begin to grow inside the walls and on the wall surfaces. In the early stages, mold appears as dark or brown spots grouped together densely. Even if you can't see it, mold may still be developing inside walls that have absorbed water from a leak.

• Mold can cause allergies and lead to other serious health issues. If you see mold on your walls, you should remove the mold and repair the leaks in the wall.

Notice the musty smell. If you don't visibly see water behind the walls, you can detect it using your sense of smell. Water that seeps into the walls doesn’t have a chance to dry out, causing the walls to start emitting a damp, musty odor.

• Musty-smelling walls often come with other signs of leakage (such as discoloration), but this doesn't always happen; sometimes, the musty smell is the only indicator that water has deeply penetrated the walls.
• Drywall can absorb water very well (almost like a sponge), which may prevent obvious signs of water leaks from showing.

Listen for dripping sounds. Even if there is no visible damage, you can still detect a water leak. Pay close attention for a few seconds after you turn off the shower, flush the toilet, or turn off the faucet. If you hear a faint dripping sound coming from a nearby wall, this sound could be caused by a leaking pipe.

• Newer PVC pipes amplify the sound of water dripping, making it easier to hear. If your house uses older metal pipes, you may find it harder to hear the drip.

Watch for increases in your water bill. If there is significant water seepage into the walls, you may notice a rise in your monthly water consumption. For example, the U.S. Environmental Protection Agency states that a family of four typically uses no more than 45,000 liters per month during the colder months. If your usage exceeds this amount without explanation, it may be due to a water leak.

• Of course, this won't tell you exactly where the leak is, but it at least lets you know that there is water leaking somewhere inside the walls.

Determine if the leak is due to a broken water pipe. Turn off all faucets and water-using appliances in your home, then note the reading on your water meter. Three hours later, check the meter again: if the reading has increased, then a pipe inside your house is leaking.

• If the meter reading hasn't changed in 3 hours, then the water seepage isn't coming from the pipes. Water might be dripping from the roof, down the walls, or entering through the basement walls.

Inspect the gutters and downspouts. If the issue isn't with the pipes, the water infiltration could be due to clogged gutters or downspouts. Rainwater (or melting snow) with no proper drainage will eventually seep through the roof and walls. If you find that the gutters or downspouts are blocked, you’ll need to clear debris (such as leaves) and restore the flow.

• Even if you don't see water seeping into the walls, it's a good idea to check your gutters and downspouts annually to ensure they aren't clogged.

Check for water seepage in the foundation walls. Under the right conditions, water can infiltrate the home through the foundation walls. This type of leak is rarely caused by the water pipes. Cracked and damaged foundation walls allow water to enter, eventually flowing into the basement. Water leakage in foundation walls is typically dealt with in two ways:

• Outside: Excavate around the foundation and seal the entire below-ground portion of the foundation with caulking material or a protective retaining wall.
• Inside: Remove damaged columns and drywall, then seal the cracks with epoxy resin.

Detect moisture in walls with a moisture meter. A moisture meter is a device that is applied directly to the wall to analyze the moisture level. If you suspect water seepage in the wall but can't pinpoint the exact leak location, place the meter at 5 or 6 spots on the wall. The area with the highest reading will be the one closest to the leak.

• You can purchase or rent a moisture meter at stores selling home repair tools. This equipment is commonly used by home inspection professionals to detect leaks or damp walls.

Use an infrared camera to locate cold, water-damaged spots in the wall. An infrared camera detects heat and can show the temperature of the wall. Areas affected by water tend to have lower temperatures than the surrounding areas. Scan the wall with the infrared camera to identify the coldest spots, as they are likely closest to the leak.

• When viewed through an infrared camera, hot objects appear red or orange, while colder areas show up in blue or purple.
• You can rent infrared cameras from home repair centers or photo shops.

Cut through drywall to find the leak source. Use a utility knife to make a cut approximately 25 cm long in the drywall at the area showing signs of water damage (such as mold, discoloration, etc.), then use a saw to cut along the incision. Make the hole large enough for your head to fit through. Look around inside until you find the source of the leak. If necessary, you can expand the hole to allow for a flashlight to illuminate the inside of the wall more clearly.

• Typically, the wall with water damage is not located directly in front of the leaking pipe. Water might travel along the outside of the pipe or drip down a considerable distance before it saturates the wall.
• You can purchase a utility knife and saw at home repair tool shops.

• If you suspect a water leak in the wall but cannot pinpoint the exact location, consider calling a plumber or a professional home inspection service to detect the leak.