How to check for hidden leaks and high water pressure
To check for water leaks, run three checks. Put food coloring in each toilet tank and wait 10 minutes. Read your water meter, use no water for two hours, and read it again. Then screw a pressure gauge onto an outdoor faucet. Color in the bowl, a moving meter or a reading above 80 psi means something needs fixing.
Hidden water leaks and high pressure: what you're checking
The EPA says household leaks waste more than 9,300 gallons per home each year on average, and 9% of homes have leaks losing 50 gallons or more a day. Fixing the easy ones can trim a water bill by about 10%.
Silent leaks are the target. You can see a dripping faucet, but a toilet can leak into its own bowl for months. Your bill gives an early hint: the EPA says a family of four using more than 12,000 gallons a month in a cold month like January or February may have serious leaks, because outdoor watering can't explain it.
Pressure belongs in the same check. Model plumbing codes cap static pressure, the reading with no water flowing, at 80 psi. Your water utility's supply can run above that, and the pressure-reducing valve that brings it down sits on your side of the meter, so its upkeep is your job. Older homes may not have one.
How to check for water leaks with dye, a meter and a gauge
- Dye each toilet tank
Add a few drops of food coloring to the tank, not the bowl, and don't flush for 10 minutes.
- Check the bowls
Any color in the bowl means water is passing the flapper. Flush afterward so the dye doesn't stain.
- Read the water meter
Find the meter, note the full reading and take a photo. Choose a time when nobody needs water for two hours.
- Wait, then read again
Make sure the ice maker, washer, dishwasher and sprinklers aren't running. Any change means a probable leak.
- Look where water hides
While you wait, check under sinks and behind the fridge, washer and dishwasher.
- Attach a pressure gauge
Screw it onto an outdoor faucet or a laundry faucet, then open the faucet fully.
- Read static pressure
With nothing else running in the house, note the psi. Repeat at another time of day, since supply pressure can change.
How to check for water leaks and read your results
| Test | Pass | Problem | What to do |
|---|---|---|---|
| Toilet dye, 10 minutes, no flushing | Bowl water stays clear | Color shows in the bowl | Replace the flapper. EPA says to do so at least every five years. |
| Water meter, 2 hours, no water used | Reading doesn't change | Reading changes | You probably have a leak. Recheck toilets, then outdoor lines and irrigation. |
| Static pressure, no water running | At or below 80 psi | Above 80 psi | Have a plumber install or adjust a pressure-reducing valve. |
| Pressure over a day | Stays steady | Climbs when the water heater runs | Ask a plumber about thermal expansion and an expansion tank. |
When a plumber sets a pressure-reducing valve, a gauge reading should guide the adjustment. One code explainer says most residential plumbers set them between 50 and 65 psi.
A few small leaks add up faster than you'd guess, according to the EPA:
- A faucet dripping once per second can waste more than 3,000 gallons a year
- A showerhead leaking 10 drips per minute can waste more than 500 gallons a year
- An irrigation leak 1/32 of an inch across can waste about 6,300 gallons a month
What to do about hidden water leaks or high water pressure
Toilets are the easy win. A failed dye test usually means a new flapper, which is a simple DIY part.
If the meter moves and every toilet passes, close your main house valve and watch the meter again. If it still moves, the leak is probably between the meter and the valve, on the buried service line. That line is usually your responsibility, though it varies, so call your water utility and a licensed plumber. If it stops, the leak is inside the house.
Call a plumber promptly for wet drywall, a warm spot on a slab floor or the sound of running water when everything is off. Dry water-damaged areas within 24 to 48 hours, the EPA advises, to limit mold.
High pressure wears on fixtures and appliances. A dripping relief valve on the water heater is a sign to call a plumber. Don't cap or plug that valve, because it's a safety device. If the relief valve only started dripping after a pressure-reducing valve went in, the fix is often an expansion tank, not a new heater.
What homeowners say about a water meter leak test
If a toilet refills on its own every so often, the flapper is usually brittle or crusted, or its chain is too short and holding it open. Adding one link of slack or swapping a cheap flapper fixes most of these. (DIY Stack Exchange)
Toilet dye test and water pressure questions
What is normal water pressure for a house?
Model plumbing codes set the ceiling at 80 psi, measured with no water running. Many residential plumbers aim for about 50 to 65 psi when they set a pressure-reducing valve. Local rules can differ, so ask your water utility or building department.
How do I know if my toilet is leaking?
Add a few drops of food coloring to the tank and wait 10 minutes without flushing. If color shows up in the bowl, you have a leak, and a worn flapper is the usual cause.
Why does my water meter move when nothing is on?
You probably have a leak, though first rule out ice makers and anything else that may be filling. Toilets are the most common place to start. If they pass, close the house valve to see if the leak is inside or on the line from the street.
Sources: jaspector.com, cstx.gov, EPA
General guidance for U.S. homes, not professional advice. For gas, electrical and structural work, call a licensed pro.