Leaking Soil Pipe?

[andrewpreece]

I'm not sure about the meaning of a test I did. First, let me explain that my grey/rain water all empties into a gully on the side of my house. I think it empties into a salt-glazed sewer pipe. The sewer pipe is buried under a concrete ledge running along the side of my house.

After about 8 feet horizontally a soil pipe from the upstairs loo enters the same concrete ledge, and joins the same sewer pipe, i.e. my sewage and rainwater all empty into the same pipe. Just before the sewer pipe reaches the road there is an inspection chamber, and whilst looking in there for a completely separate reason, I rashly decided to do a leak test.

I bunged up the sewer pipe in the inspection pit, then went to the gully and ran water into it until it filled up the ceramic pipe draining the gully to the lip. The water level then dropped two inches in some 40 seconds or so, then dropped much more slowly. I repeated the test and listened for what I could hear along the route of the sewer pipe, and distinctly heard water gurging for 40 seconds where the soil pipe enters the concrete ledge.

Sorry to bang on in such detail, but my question is, would you folks expect the ( unseen ) join between a soil pipe and a sewer pipe to be airtight, or is it arranged so that flowing water coming down the soil pipe negotiates the join ok, but standing water being pushed back up a few inches above that join will leak out?

Do I have a problem, or am I meddling with stuff I don't understand? :-)

Andy.

[Set Square]

Is it possible that you trapped some air in the pipe - which subsequently gurgled out, causing the water level to fall? If so, you may not have a leak at all.

Although I'm not by any means an expert, my impression is that leak tests are normally performed by bunging up *both* ends of a pipe and then pressurising it with air - and measuring the pressure drop over a specified time.

[andrewpreece]

It is possible some air was trapped I suppose, but the sound I heard was trickling, definitely water on the go. At any rate, no air would have been trapped in the soil pipe, as of course it opens to the air at the eaves via the stench pipe.

Also, I repeated the test three times, with identical trickling noises, and a fall of the free surface of the water by about 2" over about 40 seconds, whereupon it slowed to less than an inch over 5 minutes.

I cannot perform an air pressure test without much ado, but if you say that a sewer pipe should be able to pass an air leak ( when stopped up at the ends ) then I reckon I've definitely got a problem. I wasn't sure if a metal soil pipe-to-glazed sewer pipe connection had to be air tight or merely be able to take a vertical fall of water without leaking ( in the same way a roof is waterproof but not watertight ).

thanks,

Andy.

[O.B.]

There should be a trap between the gully and the junction. After that it should be airtight.

[Set Square]

Whilst again not claiming to be an expert, I believe that it needs to be air/water-tight so that leakage doesn't occur into the surrounding soil if the pipe ever gets blocked further down, and backs up.

[Rick]

When you put a new pipe in, its necessary to preasure test it in the way being done here, to ensure there are no leaks.

I assume the desire is to stop groundwater contamination, and unplesant odor.

Rick

[andrewpreece]

There is a trap leading off from the gully. It was whilst cleaning sediment from the trap ( yuk! ) that I decided to do a leak test.

I've decided to bash away the concrete cube that was cast around the bottom of the soil pipe where it enters the concrete ledge on the side of my house and have a look. I will try and post what I find in case anyone is interested, as the leak test I performed is quite easy for anyone ( with the same plumbing ) to do.

Andy.

[andrewpreece]

Well, as in the previous thread of the same name I have now smashed open the concrete surrounding the joint between the cast iron soil downpipe and the saltglaze sewer pipe where I fancied I had a leak and found a cavity about a cubic foot in size and a badly cracked 135 degree salt-glazed pipe which connects into the rainwater drain from the gully, via a teeing-in pipe.

The teeing-in pipe has cracked flanges too, though it doesn't visibly drip water like the cracked soil pipe connection: that lost half a cup of water each time I flushed the loo.

Questions:_

Is it best to replace like with like, or can I use plastic sewer pipe?

Do I have to take up two sections of sewer pipe at the same time, in order to be able to fit them together?

Is it easy to separate salt-glazed sewer pipes that have been cemented together at the join without running the risk of fracturing the good pipe?

If there are hairline cracks on glazed pipes, can I just coat them with something ( I dunno, like bitumen ) an bury them back in concrete?

cheers,

Andy.

[Chris Bacon]

Plastic is fine, you'll need connectors, though, and the pipe should be encased in concrete.

Depends on your connectors...

No, it's difficult. You *might* be able to do it by stitch-drilling into the mortar in the socket, but you're likely to break the socket anyway.

Replace or encase in concrete.