New build drain test problem

[preeves]

I'm a first (and only!) time self builder so apologies if my limited background gives me away.

I am at the point where our build is ready for the final drains test and there is a problem.

I have a downstairs WC and shower room. Our plumber has run the shower and basin drains to the adjacent utility room stub stack to minimise boxing in in the shower room.

This leaves the WC on its own stub stack in the room. Nothing else is on this stack. Both these stub stacks have Durgos.

I am finding it impossible to get a pass on this stack. An air test at the inspection chamber drops away quite quickly. A water test appears impossible (this is where I may be being dumb) because I can't see how to fill up the pipe run. Flushing the WC with a plug at the IC doesn't hold for long. A trickling sound is clearly audible as the water level drops away (as you'd expect!).

I flushed it a dozen times yesterday despite this being against my better judgement because I was concerned that the build up of pressure might damage the durgo. Could it? It ought not to let air out in theory should it?

Our plumber has been over today but wasn't able to give much advice and wasn't very helpful.

I've not looked closely at the durgo because it is currently boxed in but I can easily cut into the plasterboard on the boxing if I have too. I'm guessing that someone will tell me that this is my next step. If the durgo is cemented on what course of action is open to me.

Any constructive replies would be most welcome.

 

[Pipes Plumbing]

If you have plugged the run in the IC from the stub stack and it will hold neither air or water I there may actually be a leak somewhere between the WC and the IC.

Are you 100% certain that there is nothing else connected to the stub? If there isn't and the IC is plugged properly it should happilly fill the pipe run up and continue to do so until either the plug gives way of you reach the spillover level of the WC.

Have the trenches been backfilled already?

 

[Nat]

Hi preeves,

If you are still having problems with this private message me and I'll give you my number and I'll try to help you out. I've had quite a bit of experience with this.

Nat

 

[preeves]

So sorry to have taken a year to thank you for your kind replies! I'm new to the forum and because my problem got solved I didn't log back in again. Pipes Plumbing was right. There was a leak - under the floor screed where our plumber had intended to join a waste pipe then changed his mind. Unfortunately he forgot to cap it with more than masking tape! I found it by lifting the Durgo stack out of the way, sticking my arm down the drain until I could just feel the rogue junction. Embarrassed plumber back next day, fixed and retiled in two hours. Passed drains test that afternoon! Thanks again.