How to Purge Air From Household Water Pipes

Anyone who has a very old plumbing system knows what trapped air in the pipes sounds like: It's a knocking, thumping rattling sound that coincides with water spurting and pausing from various faucets.

Because you seldom use all your water faucets at once, the trapped air can remain in the pipes for long periods of time, migrating through different branches of the pipe system and never fully leaving. To purge all the trapped air requires just half an hour and a little wasted water. .

Turn on each water source in your home, starting at the highest point. Turn both the hot and cold water on fully.

Put a screwdriver inside each toilet, in the bottom of the water closet, propping open the plunger so the toilet runs continuously.

Proceed throughout the house, working your way down to the lower water sources. Don't forget to run the washing machine and dishwasher. Open exterior faucets and basement faucets.

Observe the water flow from each of the faucets, watching it until it stops sputtering and knocking and there's a smooth, unbroken stream of water. You may notice the faucets in the higher parts of the house take longer to run smoothly (since the air in the faucets will rise).

Turn all the faucets off after they've all run smoothly for a full 10 minutes. Turn them off starting with the lowest physical positions in the house, and working your way up.

Things You Will Need

  • 1 screwdriver for each toilet in the house


  • The larger the plumbing system, the longer it takes to bleed out all the air. For very large homes, let the faucets run for 15 to 20 minutes.