Big Leak

[RTK]

I spent last weekend fixing a leak under my house...or so I thougt. When I got home last night I could actually hear the water streaming out of my "fixed" pipes. It was my first plumbing experience so expected some setbacks, but my fix has become a comlpete disaster. The problem is worse now than when I started. The main line coming into my house is iron, really old and rusty iron. I'm going to replace it with pvc out to the meter over the holidays, but for now I just want to stop the leak. All the pipes in my house are steel or iron, except the one section that joins the main line to everything else, that section is pvc. I used a 3/4" slip joint coupling to join the iron line to the pvc, but water leaks out from the iron side. I think it's because the iron pipe isn't smooth anymore, I had to chip big flakes of rust off just to get the old coupling off. I tried wrapping the pipe in teflon tape to smooth it out and to increase it's diameter a little. That worked for a while but over the course of one day it ended up leaking a lot more. Is there something better I can use to join the different pipes or perhaps I'm just doing something wrong, maybe overtightening the coupling? I would appreciate some input. Thanks.

[LazyPup]

The only methods of making a water tight seal to iron pipe is by means of a threaded coupling or a welded joint. There are no compression fittings that will effectively seal on iron pipe.

When making the transition from iron pipe to any other type of pipe the best method is to have a female thread on the iron side and the secondary material coming in by means of a male thread.

If you currently have a descent thread on the end of your iron pipe you can clean that thread thoroughly with a wire brush then apply pipe dope and screw an iron pipe coupling on the end of the pipe to create a female thread, then use a PVC male thread adapter screwed into the coupling. (Be sure to apply pipe dope to the male threads before screwing it in).

In regards to you future plans of changing the supply line to PVC that would not be my first choice. While PVC is approved for direct burial the downside is that in order to install PVC you will have a number of joints buried underground. Joints are the most common source of problems therefore I would opt to use Roll Polyethene or roll copper pipe to eliminate underground joints.

[RTK]

Thanks for the reply Lazy Pup, unfortunately the iron pipe is too corroded to thread and it's in a tight spot for welding. I could probably find a plumber to weld it but I couldn't justify the cost. I'm pretty sure the pipe is original to the 61 year old house and it's at the end of its service life, so fixing it would be a waste of time and money. If I can't fix it temporarily then I'll just stay at a friends house for a few weeks until I can run a new supply line. Thanks for the advice on my choices for pipe, I was already considering using copper after reading your reply to the post about PEX lines. I'd never heard of biofilm before but thinking about it now gives me the willies. I'm not normally a real germ conscious person but I can't stand the thought of jelly in my pipes, I keep picturing canned ham. Ignorance was bliss.

Thanks again,

RTK

[LazyPup]

While polyethelene and copper still remain the two most common types of pipe used for supply lines PEX is approved and it would be a good viable option in this application. There is a constant flow of water in the Supply line so you need not worry about Biofilm in this application because biofilm only developes in areas where the water may remain stagnant for a considerable period of time such as the end of a run to an outside hose bibb that is seldomly used or perhaps a utility sink in a workshop or basement that is seldomly used.