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,