How To: Find a Plumbing Leak

Learn to detect sneaky leaks inside your home and on your property to prevent water damage and waste.

How to Find a Water Leak

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Our homes rely on water—as long as its safely contained in a pipe, sink, tub, or appropriate appliance, like a dishwasher. But water can fast become the enemy if it goes where it shouldn’t, potentially damaging a home’s structure or furnishings. Plumbing leaks, unfortunately, are pretty common, even in newer houses, and it’s likely that every house will suffer from at least one. What’s more, not all leaks are obvious; in fact, they can be awfully insidious, making it crucial to catch and repair a leak as soon as possible. Every homeowner should know how to find a water leak, so read on for wise advice on determining whether you’ve sprung one and how to identify its location so you can nip the plumbing problem in the bud.

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Monitor the Water Bill

Monthly water bills are fairly predictable, so if you receive one that’s unusually high—and you haven’t been using excess water—you may have a leak. The Environmental Protection Agency suggests that a family of four will typically use no more than 12,000 gallons per month, except perhaps during the summer if you water a garden or lawn. Even small leaks, such as a faucet with a steady drip, can waste as much as 10,000 gallons of water per year, so keeping an eye on your water bill is a smart, proactive practice.

RELATED: 14 Sneaky Ways to Save Money on Your Water Bill

Watch the Water Meter

If you suspect a leak, monitoring your home’s water meter will give you a definitive answer. The meter is often located beneath a manhole-type cover near the street or (in areas where temperatures don’t dip below freezing) on the side or back of the house, near to where the water supply line enters the house. Follow these steps to monitor the meter:

  1. Turn off all water faucets in your home and make sure the washing machine and dishwasher are not running.
  2. Check the water meter and make a note of the numbers you see. Come back in an hour and check again. If the numbers have changed, there’s a leak somewhere.
  3. To determine if the water leak is in the house or outdoors (only for homes with meters located at the street), turn off the shut-off valve on your home’s main water supply pipe. This is either located in a basement or a utility room where the water pipe enters the home.
  4. Check the water meter, write down the numbers, and wait another hour. When you check again, if the numbers have not changed, the water leak is inside your home. If the numbers have changed, the leak is in the buried water line that runs to the house.

Check for Patches of Greener Grass

Everyone wants a lush lawn, but if an area in your yard is much greener (and grows faster) than the rest of the grass, it could indicate the spot where a buried water line is leaking. If the leak is profuse, you might even see some puddles on the surface of the ground.

How to Find a Water Leak by Sinks

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Investigate Appliances and Fixtures

If the water meter test indicates a leak inside your home, check the cabinets under the kitchen, laundry, and bathroom sinks to make sure they’re dry. You’ll also want to look for puddles around the bases of tubs, toilets, and showers and beneath the water heater, dishwasher, and clothes washer. If you find any puddles, turn off the water supply valve to that appliance or fixture and call a plumber.

Dye Test the Toilet

If you don’t find any puddles around fixtures or appliances, check if the toilet needs to be repaired, because it’s a prime spot for interior leaking. The toilet’s flapper (a rubber stopper that prevents water from entering the bowl until you flush the toilet) can become brittle over time, allowing water to trickle from the tank into the bowl. Grab a bottle of food coloring and put a few drops in the tank of every toilet in the house. If a toilet tank is leaking, color will appear in the bowl within five minutes. If you find color in the bowl, call a plumber or, if you’re handy with DIY projects, you can probably replace the flapper yourself.

Stay Alert to Leaking Clues

If a fitting on a supply line under your sink breaks and a spray of water comes shooting out, you know immediately where the trouble is, but some leaks are a lot sneakier! At worst, water may be trickling slowly from pipe fittings within a wall and go unnoticed until it causes extensive damage. Even if the water meter test indicates that you don’t currently have a leak, one could develop at any point in the future, so it’s a good idea to keep an eye out for:

  • Wall discoloration. This could indicate water leaking from behind the drywall and soaking through to the front side. Water stains on ceilings and walls are usually yellowish or brownish in color.
  • Bubbling paint or bulging wallpaper. Both are signs that the wallboard is wet and the paint or wallpaper is no longer adhering tightly. In some cases, you may also notice a bulge in the wallboard, which indicates the water damage is more extensive and the wallboard will have to be replaced.
  • A dripping sound. While some leaks are totally silent—for instance, if water is traveling along a wall stud—other leaks can sometimes be heard, giving you a clue as to the leak’s location.
  • A musty smell. Over time, a persistent leak provides the perfect humid environment for mold to grow. In some cases, you may notice black splotches on the outside of the wall, but often, mold will grow inside the wall where you can’t see it, so a musty smell is a red flag.

All of the above are signs of a leak, but keep in mind that not all water leaks are plumbing leaks. The water could also be coming from a leak in the roof or around a window. Either way, leaks should be addressed promptly to reduce the risk of water damage.

How to Find a Water Leak with the Help of a Detector

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Leak Detectors Offer Immediate Notification

Some fixtures and pipes are more prone to leaking than others. An older water heater can develop pinholes along its bottom due to corrosion inside the tank, and water pipes that lead to exterior water faucets can freeze and burst during cold winters. So you may decide to install leak detectors, such as Zircon’s Electronic Leak Detectors (available from Amazon), in these areas. A battery-operated detector will emit a shrill alarm when it detects even a small amount of water, so you’ll be able to turn off the water supply and have the leak fixed before water wreaks havoc in your home.