Using compressed air to clear water line

by Ronnie
(California)

The home inspector noticed that two bathroom faucets in separate bathrooms are only letting a little water when you turn on the faucet.

Since the bathrooms back each other he felt there was a common line which was blocked. He said the plumber will probably shoot some air through the line and it's probably some cap (I don't remember exactly)which came off and is stuck in the line.

Well with money tight in fear of a huge plumbing bill I figured, hey how come I can't blow some air down the line. Now for the hard part, how exactly do I do that?

Any and all advice would be appreciated from what type of air blow gun and compressor I'd need to how to access the water line. Do they rent compressors and would any other tool do the job? Thanks in advance.
Ronnie

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Hello Ronnie...sorry to hear about the blocked water line.

Nope, I'm not a plumber, but some things just have to be considered if you are going to attempt this project yourself.

I guess it's 1/2" copper pipe we're talking about, right?

Before we talk about the compressor, lets consider these questions.

How will you blow air into the pipe? Your plumber has the skills, and maybe an adapter, to cut the pipe where necessary, and to be able to put the pipe back together again when he/she's done. Have you those skills?

You may not need an adapter, but you do need access to the pipe to introduce the blast of compressed air. Yup, you can just cut the pipe and stick an airline in the hole. But then the compressed air will just blow out around the airline unless it fills the opening fully.

Compressed air will always take the path of least resistance back to atmosphere, and it will vent around the air line stuck into the copper tube first before trying to dislodge whatever's in your pipe.

Next question, where, if you have the compressed air entry sealed up so the air can't escape, do you want the compressed air to escape to? In order for the pressure to do the job, air will have to go somewhere, as it always travels from high pressure to low. As long as the air can get from where you blow it in to atmosphere somewhere, then it should travel there once you've introduced it to your air line.

OK, having said all that, if you're still determined to do it yourself, don't worry how big your compressor is...rather, concern yourself with how much compressed air you can have available, what pressure it's at, and how quickly you can get that compressed air into the opening in the copper line.

Your local rental store will likely have an "air pig", which is about a 5 gallon sized air tank with an inlet, and an outlet that's either sealed by a ball valve, checked coupling, or typical tire connector.

Remembering that you want as much air as you can going into the line as quickly as possible, you wouldn't ordinarily opt for the tire connector.

Fill this air pig with 90-100 PSI of air from the local garage (or maybe the rental store has a compressor to fill it for you) and you'll likely have enough air in it to do the job for you, without buying or renting a much more expensive compressor.

Still and all, if you aren't comfortable doing it yourself, the lower cost option (in terms of cash spent, time spent, cleaning up the mess, and actually achieving the solution you want) may be to hire the plumber to do the job.

After all, they just "guessed" that you had a plugged line. What if it isn't?

Cheers,

Bill