Hi there,

I have a slow leak in a drain pipe in the basement... but by the sound of it, it drains all three units of a "triple-decker" house built in the late 1800s. It's pvc pipe, probably installed in 1999. The problem is that I can't tell exactly where it's leaking from: I wrapped one joint in JB WaterWeld but it wasn't the right joint in the end, and the drip continues to slowly increase in volume.

I don't want to just fill a bucket over time, because (1) that's just a lousy half-assed solution and (2) it's dripping onto wood beams which will cause rot.

So, I'm wondering if this might work: I get leak-detection dye... and start on the first floor... put some dye in the sink, run the water: if it comes out, I know the leak lies below the first floor level. If it doesn't come out, then the leak must be above that level. Then I move up to the 2nd floor and do the same, and the 3rd floor if needed.

Will this work, you think? I've never used the dye and just recently saw it for toilets; don't know if it would work with sink drain flow. We're going to have to cut holes in walls to access this, and since water flows down, dripping in the basement could be from anywhere.

Thanks kindly for any advice!

Also: when a plumber cuts a wall hole, do they patch it up after, or do I have to find someone else to do that once the plumbing is done? Thankfully I haven't had to do work that large yet.

The dye may show you which line is leaking but not necessarily where. Plumbers make holes but usually do not do the patching. I'd call a few plumbers and see what they have to say and a rough estimate.

Why isn't the pipe that has the moisture the one that has the leak? Is it possible to take some TP and track the moisture back as far as you can?
In my area when we cut a inspection hole in the wall we cut a square and save the cut so all that needs to be done is tape the patch back in and paint the tape to match. Let me know what you find. Good luck, Tom

Yeah, I didn't explain thoroughly. It's dripping into the basement, but runs straight up from there, so I can only see for a foot or so before the space gets too narrow even for my hand. As far up as I can reach, I get moisture, so it's coming from above that... but I don't know how far above it.

One friend, who is a plumber out of state, said it sounded like a job requiring cutting above, dropping the whole big thing out, reconstructing it and then fitting it back in... but if it's a floor above, that seems nuts overkill!

Of course, using the dye as I described won't tell me which joint exactly is leaking, just which floors it's between. If knowing that won't make a difference in how we fix it, then I won't mess around and waste time...

I did just get some cake decorating dye, though! Fun colors at least... heh.

I don't get what you mean by using TP...

Thanks!

when I track a small leak I take a wad of toilet paper and run it down the pipe until bit picks up moisture, your plumber friend was correct. To locate the leak you will have to open up walls. I just don't see any other option. Good luck, Tom