View Full Version : sealing threaded water pipe leak after installation

10-20-2005, 06:29 PM
I have a problem. I just installed a 3-stage whole house water filter in my basement, and the unit has a slow leak between the first and the second filter stages. The entire unit is made up of three 20" filter cartridges that are connected together with a short piece of double threaded plastic 3/4" pipe. I can see that the manufacturer used teflon tape at the connections, but I'm still getting a slow leak. Since I've already soldered this in to my water line, it would be very difficult to take everything apart and disassemble the stages of the water filter to correct the problem. My question: Is there any way to repair this slow leak using some sort of liquid thread sealer or something that would "wick" into the threads and stop this leak? Any help would be appreciated. I'm just a homeowner and not very experienced in what plumbing compounds are out there. Thanks.

Bob NH
10-20-2005, 06:55 PM
If there is enough length in the plastic nipple between the filters, you might try the following:

1) Cut the plastic nipple and install a union in the line.

2) Now you can remove the leaking part and replace or fix it.

3) Store the memory of this experience and use a union when installing such equipment.

Ball valves are now available with union ends. I got some at Home Depot.

10-20-2005, 07:04 PM
I don't know of any magic goo that you can apply to this.
Is this double threaded nipple very short?
Or is there room to put a union in there with two close nipples.
Did they put a bypass around all of this so that you could work on it?
I'm a believer in unions, especially if I may work on it again.
Also it would have been handy if you had thought to put in a couple of unions, one on each of the copper............

10-20-2005, 08:02 PM
The male-male nipple between the two filters is very short (about 1/2" or so is exposed), and the entire three-stage filter module is held together by a metal wall-mounting bracket. I don't see how it would be possible to cut the nipple and add a union. I can shut off the main water supply and drain most of the water in the line by running a faucet, but I'm still stuck on how I would actually repair this. I'm hoping that I don't have to cut the copper pipes on either side of the filter, remove the filter network and completely dissasemble it and the defective nipple, and then re-install it using two copper junctions... But, if there isn't some sort of thread sealant that would wick into the threaded joint to stop this slow leak, that's just what I may have to do.

10-20-2005, 08:23 PM
The only repair is to remove the unit, then take the leaking joint apart, redope or tape it, then put it back together again.

10-21-2005, 10:08 AM
Since you have to redo the job you may consider to modify yours installation a bit.

I did the same job recently and I thought it would be wise to install unions and shutoff
valves on both sides, bypass valve and filter flush valve. Also I added two pressure
regulators and four pressure gages. (See the attached picture).

- Vitaliy