How to Find a Leak in the Plumbing of Your Home

Outdoor hose bib spigot.

I recently had my septic tank pumped out and noticed a steady stream of water coming from the house drain pipe into the tank. Where could it be coming from?

Hi Betty,
The most likely culprit is a leaking toilet, but there are a couple of other possibilities to consider as well:

  • Start by inspecting the plumbing fixtures in your home—such as sinks, showers, and tubs—to be sure water from a faucet isn’t literally going down the drain.
  • Next, check to see if your toilet might be leaking by closing the cut-off valve and flushing it. Give it 5-10 minutes to fully drain, then check the pipe into the septic tank to see if the water has stopped flowing. If it has, the problem is with that toilet. If it’s still running, try the same procedure with any other toilets. If you find that the problem is with one or more of your toilets, check out our article on How to Repair a Toilet to see how to go about fixing it.
  • If the mystery leak still isn’t solved, check to see if there are any other sources of drain water you haven’t considered. Some that come to mind include a basement drain, the drain line from an air conditioner unit or hot water heater pressure relief valve, the drain from the pan under a water heater or washing machine, and the backflow from a whole house water filter. While most of these are usually plumbed to drain outside on the ground, it’s possible they were tied into your house plumbing drain system.
  • Another way to check to see if the water is coming from the plumbing inside your house is by monitoring your water meter over a few hours when nothing is running (be sure to turn your ice maker off!). If there aren’t any leaks or water flowing from your supply lines into the drain, the dials on the water meter won’t move.

Good luck,



  1. I have the same problem i truned off all water to the house at the whole house water filter also im on a well.No water going to house but still have small leak. It did get less flow when water turned off,im thinking water was just sitting in pipe.But when turned water back on water stream got bigger again. Im lost at whats leaking.

  2. I have abroblem in the house water leak Icheck toilet not . when turn on water meter runing fast but Ican hear nothing water leak .Iam lost at whats leak.

  3. My son got a $450.00 water bill. He call the water co. thst cam out and said it is not on the city sideand left. You can not hear a leak the ground isn’t wet. How can you check
    for leak unground. Thank you very much

    • Hi Sharon,
      The best way to check is by monitoring your water meter when you’re not using any water in the house. Click on the “monitoring your water meter” link in the article above to see how to go about it. Also, most cities will give you a one-time credit on your water bill if you can demonstrate to them that the high bill was caused by a leak. At the very least, they should credit you for the sewage part of the bill if the water that was leaking wasn’t running into your drain line.

  4. I have a shut off valve to is connected to my water filtration system. During a servicing of my ice maker I had to turn the valve off and on several times. Now I see a slow dripping from the valve. What is the best way or easiest way to stop the leak?

  5. No hot water tap is open but the instant hot water goes on which means the hot water must be leaking somewhere in large quantity.
    How can I find this leak?

  6. We have would looks like a water stain at the top of our house in the far corner, but more like an oil stain. It’s 110 degrees here and its not only at the top but about sixteen ft down there is a small stain at the top and on the bottom of the window that looks like the same. I had a plumber come out and he did a water test and checked the meter and said its not water leak or mold. I am not sure if this is possible but about 4 months ago we had a beehive removed next to that same area and they had to spray something up there. Could it be dried honey melting down or between the stucco? we have not ran our AC in over three years since adding a whole house fan in the attic. also the wall near the window is not sticky.

  7. We just discovered a thin sheet of water on the basement floor. The obvious culprit was the dishwasher which is over the wet area or possibly the sink. I checked under the dishwasher and sink and saw no evidence of water. We ran the dishwasher and the sink, but no evidence of leakage. The bathroom and toilets are in another part of the house. On the basement wall there are a pair of 2.5 to 3.5 inch diameter pipes which are embedded in the cement floor. branching out from these pipes is an open ended pipe of the same diameter. My impression is that this is somekind of pressure release valve. Question: what do you think this pipe extension is, and could that have overflowed
    Mike Marsh

  8. I am totally confused! I had my septic tank pumped out Monday and there was a stream of water coming from the pipes. I read your “How to do ” articles and I did as it said to. I closed off both bathroom commodes to see which one might be leaking. even after the water to both was off there was still a steady leak. I changed both flappers. Still leaking. I live in a trailer and my central air plus my bedroom a/c dont have anything to do with the water lines. I am confused… so anymore suggestions on how to find out why there is a steady stream of water? help

  9. I recently noticed a dripping water sound somewhere in the sink area in the bathroom. I also noticed that it stopped each time the heater turned off. It started up again when the heater went back on. I’m wondering if this is coming from the heating/air conditioning unit which is located above in the attic. It does have a pipe running into the bathroom sink pipes below. Any help would be appreciated.

  10. My water usage and water bill have increased greatly. The leak indicator on the water meter goes around slowly, from time to time, but can be stopped by turning off the main valve and then turning it back on again. Usually, the leak indicator wheel doesn’t move, for a while, but then starts up again.

    We’ve turned each toilet off, checked the leak indicator. There is no leak in any of the toilets. No leak around the hot water heater. Nothing around the water softener tank.

    Any suggestions on how to pinpoint this leak?

  11. Is it possible for a hot water heater to leak into the septic tank? After checking all previous posted possibilities for a steady drip into septic tank, I have come down to the water heater, which has a constant running water sound. I was told by a plumber that it was a recirculator that constantly ran. He assured me it wasn’t a problem. Is there a way to shut off or check if this is where the leak is coming from? Does the hot water tank even drain into the septic system? Thank you.

  12. We have an open ended pipe coming straight down from the ceiling in the basement, there is about 2 feet between it and the floor. We drained our radiatiors and now there is a constant stream of water coming out of this pipe? We have lived here for 8 years and never had anything coming out of this pipe? Help??(*It has been about 5 days now and we have to go down every hour to check the bucket we put under it and empty it).

  13. I have a water leak in my hall way, it is about 1 inch deep on concert floor I have no leaks from the radiator in the hall way nor the down stairs toilet.

    Once I mop it up it is back after a few hours, I have checked my meter and it’s not going round when all water turned off so no leaks under ground.

    Please help what can I do?

  14. My hose bib is was leaking so i took it off and i’m trying to solder it back on, but the condensation from the water in the back pipe keeps the solder from feeding in the copper when real hot. How do i stop the water?

  15. Hello, please help. The phone company dug a hole deep enough for a 5′ worker to stand in up to his chest around my water meter on my side of the water line. A few weeks later, my neighbor and noticed the hole was sinking and when I walked over the area it was like walking on a sponge. We been having an unusual amount of rain before and immediately following the digging of the hole. I also, noticed a water leak, where the water was shooting out of the ground shortly after the rains. The sub-contractor fixed the sinking hole and admitted the severe leak was caused by their work. However, 14 days later I noticed my water meter was still moving even after the leak repair. The sub-contractor refuse to check for a possible second underground leak. There are no wet spots on my lawn. How, do I determine if there is another leak on my water line?

  16. The sub-contractor that caused the damage of my water line underground fixed the water line by cutting out the damaged area and reconnecting the two open ends with a pvc pipe held together with metal clips on each end, instead of using a bonding substance as it was done when I had a leak years ago. Was using metal clips the correct way to fix an underground pvc water line? If, not could the line still be leaking? Help please,they wouldn’t call a plumber to do the fix.

  17. At my son’s house.We woke up this morning to water on the floor.we traced it back to the laundry room.There is no water on the laundry room floor.It seems to be in the wall around the faucets .What can this be?

  18. I keep hearing the sound of toilet flushing, but no toilet has been flushed. It then sounds like pipes hitting together, then all sounds stop. They seem to cycle all of this every few minutes or so. What can this be. ????

  19. only 2 toilets go to our septic, all other gray water is diverted, i too have water running water from pipe into septic tank, neither one of the toilets are leaking, so where is this water coming from and how do i fix it????


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