Keep getting air in pipes

[Homerboy]

Flush the toilet -- pipe rattle.
I get rid of it by shutting off main. opening all the faucets in the house and letting the water/air expel.

Works fine, but withing a few months I get it again.

Not a huge hassle to fix it, but why does it keep happening?!

 

[MagnusTheBrewer]

A plumber would have to examine your pipes to tell you that. However, you may be able to fix it by installing an arrester on the water pipe. It's basically an air reservoir with a membrane to separate the air from the water and acts to dampen water hammer.

 

[C1]

The explanation given as to the temporary cure is actually confusing. Turning off the main & opening valves typically drains water out of the pipes resulting in letting air in. (The standard approach is to open the main then purge any air in the pipes by opening the faucet/outlet valves letting the water run.)

Normally for a rattling pipe, the cure is to secure it (but in your case it's probably in the wall). Check to ensure that the water pressure is not excessive. Then make sure that the toilet valves (shut off & tank fixture) are not the cause (eg, a loosed rubber washer in the shutoff to the toilet tank that might be causing "fluttering").

 

[Slacker]

http://m.dummies.com/how-to/content/how-to-quiet-noisy-water-pipes.html