Undiscovered leaks in your home’s water supply could end up costing you hundreds of dollars per month and even result in severe damage to the structure of your living space. Luckily, it’s pretty easy to find the source of many leaks and save yourself considerable money, provided you know what to look for. If you think you might have a leak but haven’t yet received a notice from your local utility board, your best bet is to check common problem areas for tell-tale signs of escaping water, such as drips, moisture damage, or noisy pipes.

Checking Indoor Appliances and Fixtures

Watch for changes in your water meter to confirm that you have a leak. Before you do anything else, shut off the main water supply to your home and take a close look at your water meter. If either the normal or low-flow indicator hand is moving, it means you have a continuous leak somewhere in the line. On newer digital meters, the tipoff will be seeing any number other than “0” on the flow rate screen.

• All homes are equipped with water meters designed to simplify billing and help homeowners keep track of how much water they’re using on a regular basis. In most cases, your water meter will be in a protective “box” near the curb or sidewalk in front of your home.

• Minor leaks may not create enough lost water to show up on your water meter right away. To be absolutely sure, wait 1-2 hours after your initial reading and take a second one. If the second reading differs from the first, you’ve got a leak.

Eyeball the pressure relief and drain valves on your hot water heater. Once you’ve determined that you've got a leak on your hands, it’s time to locate it. Start by heading to your hot water heater and looking for pooling on the surrounding floor. If the cause is a dripping valve, it probably just needs to be replaced. If the valves are dry, there’s a chance that the leak is inside the tank, which means you may need a brand new water heater.

• You’ll find the pressure relief and drain valves at the top and bottom of your water heater, respectively.

• Listen closely for dripping, gurgling, or hissing sounds, as well. It’s possible that your leak hasn’t yet manifested visibly on the outside of the water heater, but it may still be detectable audibly

Examine each of the toilets in your home. Add a few drops of dark food coloring to the toilet’s tank, then wait half an hour or so without flushing the toilet. After that time, look to see if the dye has made its way into the bowl. Assuming it has, the problem is most likely a worn-out flapper valve. However, a bad flush handle may also be the culprit. Your next step is to identify which component is to blame and pick up a replacement at your local hardware store.

• The majority of toilet leaks originate at the flapper valve, which is the rubber seal that moves up and down when you flush the toilet. You’ll often hear the water running continuously if the flapper valve isn’t sealing properly.

• If you think the flush handle might be the problem, try tightening the nut securing it to the side of the tank, or adjusting the length of the chain so that it’s neither too taut nor too loose. If neither of these solutions works, you may need to replace the handle altogether.

Look for leaky showerheads and drains. While you’re in the bathroom, take a peek inside the shower. Spotted pooling is usually due to a partially-open curtain or sliding door that’s off alignment, but in some cases, it may be the result of a dripping shower head, broken tile, or loose drain connection. Re-seal or replace these at your earliest convenience to prevent the need for more serious repairs later on.

• You can test your shower’s drain by covering it with a test plug, running 1–2 inches (2.5–5.1 cm) of water into the basin, and waiting to see if the water level goes down inexplicably. Failing sealants can allow water to escape around the edges of the drain.

• In rare cases, structural damage to the walls or floor underlying the shower stall may be behind the leak. If caulking problem areas doesn’t fix things, these types of leaks may require professional intervention.

Pay attention to evidence of water damage around sinks and faucets. If you’re lucky, you’ll be able to spot the source of the leak with your own eyes. Otherwise, look for water stains, swelling, or rotting in the surrounding wood or particleboard. Tightening the faucet base, replacing cracked handle or knob valves, or scraping away and applying new waterproof caulk around fixtures will remedy most small-scale point leaks.

Detecting Leaks Outside

Go around and inspect your home’s exterior hose bibbs. The “bibbs” are the faucet-like pipes on the side of your home that you use to hook up a watering hose. These may be actively dripping, or they may hiss or vibrate faintly as water passes through. 9 times out of 10, you can stop a leaky bibb by tightening the packing nut that secures the handle or replacing a worn-out washer inside the handle assembly. If neither of these solutions work, call a plumber and have them trace the leak further back into your pipes.

• The average home has 1-2 hose bibbs on either the sides of the front and back, but particularly large homes may have more, so be sure to make a thorough search.

• Hose bibbs are most often connected to the water lines in the basement or crawl space. This is where you should start searching for the source of the leak if it doesn't seem to be coming from the bibb itself.

Assess the condition of any water accessories you have in your garden. This includes things like hoses, taps, fountains, water ornaments, and irrigation systems, such as sprinklers. If any of these accessories show signs of heavy deterioration, it may be time to chuck them and get new ones.

• A leak doesn’t need to be a bubbling geyser to be a cause for alarm—even a slight, consistent drip could point to a problematic rupture somewhere in the intervening water lines.

• A good way to catch leaks that aren’t steadily flowing is to note when a fixture or the surrounding terrain appears to be wet despite a lack of recent rainfall.

Scan for clues that might indicate a break in your underground water lines. Make a circuit of the area between the meter and the main shutoff valve inside your home. As you do, look and feel carefully for standing water, overly soft or muddy patches, or grass that’s significantly greener or appears to be growing at a faster rate than the rest of the lawn. The presence of any of these signs means that it’s time to call a plumber.

• It’s also possible to conduct a more definitive test if there’s a shutoff valve at the meter itself. Use the valve to temporarily stop the flow of water. If there’s still activity on the meter, it means the leak is somewhere between the meter and your home.

Call a pool specialist if you think you have a leak in your swimming pool. While some swimming pool leaks will be obvious, most will be much harder to reliably diagnose and repair than more common household leaks. Dial-up the pool’s original installer or search for a reputable maintenance company and have them come in and sniff out the leak for you. That way, you won’t be forced to watch time and money go down the drain hunting for it on your own.

• If the water level in your pool keeps dropping rapidly in spite of your efforts to keep it filled, chances are good that there's a leak somewhere.

• There are lots of places where something can go wrong in a swimming pool: the pump, the filter, the skimmers, the vacuum lines, or even the lighting elements or drainage systems. The fact that pools are so complex is precisely why it's so important to call a specialist if you believe that you have a leak.

• This piece of advice also applies to large decorative fountains, in-ground manmade ponds, and other major water installations.