How to remove air in water pipes?

Fixing water pipes usually means turning the water off at the main valve. Anytime the household water delivery system is opened, air gets into the system. When the water surges through the repaired system, trapped air can become both a nuisance and a problem that will cause damage. Water rushing past air pockets can cause an annoying high-pitched whistling noise every time someone open as a faucet. Water can also compress the air causing air hammers that slam into pipe joints. This can actually break connections apart.

Removing air is a simple process. Once the repair is complete, before turning the water supply on, open two faucets. One should the be faucet furthest from the water supply's entrance point to the building. The other should be at the closest location to the closure. Turn the master water supply on, and allow the water to run to and out each of these faucets for about a minute. Then go through the building opening every water outlet for a few seconds each before turning the faucets to the off position.

Once each faucet has been turned on, let run a few seconds, and turned off, all air should have been purged from that branch of the line. Remember to flush toilets as well. Separate purges are needed for both hot and cold water. When each faucet has been purged, turn off the one closest to the water supply first and then the one furthest from the supply. All air should now have been purged from the water system.