Drains testing - Using drain test plugs / stoppers

[RomanAbramovich]

I'm attempting to water test a newly laid run of underground drainage, using 100mm stopper. However, I can't get the stopper to stay in place. Even when it appears to be rock solid, every time I fill the system with water the plug gives way after 10 mins or so. There is approx 16 linear meters of 110mm pipe before the stopper.

Is there a knack to using these stoppers? Or do I need to use another item in conjunction with the stopper, to ensure it holds in place?

 

[Hugh Jaleak]

Head of water is probably too much, any reason why you're doing a water test? The thin bungs are usually fine for an air test but if a water test is required you may have to look at using the longer inflatable type bungs, or prop the thin bungs in with a couple of pieces of wood.

Tie a rope to the bung before adding water, allows you to release the water without getting soaked, and if the bung does make a break for it you wont lose it downstream! May also be worth tying off the wood as well if used, allowing that to be pulled out from the surface.

 

[RomanAbramovich]

BCO inspected today and passed the underground drainage system from a regs point of view, but advised I do a water test, as they will want to do the official drain test immediately prior to occupation. 10 linear meters of pipe runs under what will be a ground bearing solid floor, and he made the point that it would be a shame to dig it up because a drain test failed!

..so I dashed out to buy the plugs this afternoon and then sweated over the testing until dusk, with no result.

As you say it will no doubt be the head of water being too much for the bung.

On the positive side, no leaks were visible during the times the system was filling.

Should I do an air test too? Or does a water test trump that?

 

[TeaTime]

If you have the ability to hydrostatically test, I would always do that in place of a pneumatic test.

 

[RomanAbramovich]

Cheers for the advice.

Reading through previous forum posts, seems it's not uncommon for a drainage system to pass a water test and fail an air test, with the major point of failure being the air test kit itself! Therefore not convinced of the value of heading out to buy a kit that might be next to useless, especially given water test supercedes the air test.

I'll attempt to retest with the bung...

 

[RomanAbramovich]

...problem must have been with my technique when fitting the bung, getting it perfectly square inside the 110mm pipe before tightening. Test has held for 2 and a half hours now. After the first 30 mins water level dropped 2cm, then stabilised. I'll give it another half hour but it looks like jobs a good un.

 

[Hugh Jaleak]

Nice one! I recall a job from my youth, where one morning, the plumbers and the ground workers were very near to blows. Once I had deciphered the language I realised that they had a problem. The drainage system was failing a water test, (miserably!), and the argument was over who's fault it was. Plumbers were blaming the drain, ground workers were blaming the stack.

BCO duly turned up later that day and to my amazement, the test suddenly held, and the BCO passed the run. After being swiped round the back of the head to keep quiet, my attention was drawn upwards. One of the ground workers was on the roof, holding a hosepipe shoved in the top of the stack......