sewer downpipe leak

clone1

the downpipe on the back wall of my house has a join where two pipes meet - i've noticed a slight leak at this point. I tried sealing it with weather proof silcone seal - but the leak has ocurred again. What is the best method of sealing?

db

I had this problem before and it turned out that there was a blockage further down putting pressure on the join. Once the blockage was cleared the leak disappeared and has not been seen since.

Victor

I concur with db, if the pipe is vertical, there should be no pressure available to force the water through the seal.

Unless the seal is fitted upside-down

rooferPete

Hi,

Plastic or Cast Iron ?

Take care with one tube cures all silicone it rarely does even part of what it says on the tube.

A small leak can be caused by a blockage as the previous posts point out, however the water that runs down a pipe goes around the sides so it is possible for a verticle pipe to leak.

There is usually a fairly easy to see cause of the trouble, some of the joints have the top and the bottom exposed, not what the fitting was designed for but like everything else they have been abused.

.

clone1

Thanks for the replies - it is a plastic pipe. Its a new house - and I suspect that it as rooferPete suggests that the leak is caused from the water running down the pipe on the sides. I was thinking of some kind of plastic ring that I might be able to place around the join and tighten, or is there a better way to get rid of the leak.

Gordon Gekko

Just on that, and sorry to divert your thread slightly clone1, but further to what rooferPete enquired re cast iron or plastic pipe, I have a leaky cast iron pipe - its got vertical cracks just where the soil pipe meets the concrete path out the back of the house, and every time the ensuite is used there's a spread of water coming from those vertical cracks.

Our plumber, when having just a v. quick look at it during a break one day, said he reckoned the cracks were in an asbestos soil pipe into which the cast iron one fits :eek: - I really hope not, am so sick of dealing with asbestos, has cost me a fortune to remove an asbestos roof already, and this would doubtless be way more expensive cos they'd have to uproot it from the concrete path. He claimed cast iron doesn't crack vertically - the cracks are about 4 inches high, starting from where the pipe meets the concrete path. The cast iron pipe is 60 yrs old.

Any ideas? I had been hoping to try the 'miracle silicone cure' too, but rooferPete has slightly put a 'damper' (excuse the pun!) on that plan.

rooferPete

Hi,

Cast Iron will crack in any direction a lot of the problems on soil or rainwater cast iron pipes is at the collars where they join together.

The way they used to fit the pipes was into an earhtenware (clay) pipe that continued underground as the drains, I can't remember coming across asbestos used at or below ground level.

Asbestos pipes were used as rainwater, soil and flues, I find it hard to understand why a cast iron pipe would have been joined to asbestos at any point because plastic was cheaper and easier to use.

I expect your plumber knows what he was looking at, if the problem pipe is asbestos it might be possible to clean it and seal it with Isopon.

.

Victor

Gordon Gekko wrote:

Just on that, and sorry to divert your thread slightly clone1, but further to what rooferPete enquired re cast iron or plastic pipe, I have a leaky cast iron pipe - its got vertical cracks just where the soil pipe meets the concrete path out the back of the house, and every time the ensuite is used there's a spread of water coming from those vertical cracks.

Avoid using the WC in the ensuite then. :v:

I'm guessing the cracking is because the concrete is in direct contact with the pipe, with no flexibility for expansion / compression.