Pressure testing drains

[Lincolnshire Ian]

Hi 

I have been reading the bumpf from the warranty people (Self-build Zone) and have come across this:

All new underground drains must be pressure tested (air/water) at practical completion. Witnessed by the surveyor on the completion visit. A BC Cert is NOT satisfactory evidence in and of itself.

 

Surely drains will be pressure tested before the internal plumbing and soil vent pipes are installed and the trenches are still open to facilitate any repairs. To satisfy this requirement do you just test from the inspection chambers? 

I am confused, any help would be appreciated. 

Thanks 

[Kelvin]

What you do leading up to the final test is down to you so yes you should test it. Easy enough at that stage. Building control will come and have a look in the trenches at this stage but that’s all. 
 

We blocked the inspection chamber off at one end and tested at the opposite end in the garage. This tested all of the internal plumbing. BC came and watched us. 

[Nickfromwales]

4 hours ago, Lincolnshire Ian said:

Hi 

I have been reading the bumpf from the warranty people (Self-build Zone) and have come across this:

All new underground drains must be pressure tested (air/water) at practical completion. Witnessed by the surveyor on the completion visit. A BC Cert is NOT satisfactory evidence in and of itself.

 

Surely drains will be pressure tested before the internal plumbing and soil vent pipes are installed and the trenches are still open to facilitate any repairs. To satisfy this requirement do you just test from the inspection chambers? 

I am confused, any help would be appreciated. 

Thanks 

You block and fill, and then time it for an hour to prove there’s no leaks. You’ll need BCO and warranty inspector out at the same time. 

 

You don’t usually have to fill higher than the top of the lowest chamber, as long as water is visible in the highest.  

[newbuild upnorth]

our BC want a witnessed air test on all soil pipes before they get buried, I think it was 100mm/hg for 10 mins so I had to plug and test 3 individual branches to the chamber with them there, and then a final test before completion certificate which includes all traps at I think 50mm/hg

[Lincolnshire Ian]

15 hours ago, newbuild upnorth said:

our BC want a witnessed air test on all soil pipes before they get buried, I think it was 100mm/hg for 10 mins so I had to plug and test 3 individual branches to the chamber with them there, and then a final test before completion certificate which includes all traps at I think 50mm/hg

The test before the pipes get buried seems to be quite straight forward. Thanks for the help. 

The test at completion though, is a bit perturbing, do I fill up at the traps in the toilets/sinks etc, cap off the underground pipes in the inspection chambers, cap off the vent pipes on the roof and then pressurise?

[ProDave]

1 hour ago, Lincolnshire Ian said:

The test before the pipes get buried seems to be quite straight forward. Thanks for the help. 

The test at completion though, is a bit perturbing, do I fill up at the traps in the toilets/sinks etc, cap off the underground pipes in the inspection chambers, cap off the vent pipes on the roof and then pressurise?

Buy yourself an air test kit, they are not expensive and test as you go.  You want to make sure your drains are all good BEFORE you cover them with plasterboard and hide them.  And testing as you go means if you have a leak, you know it is in the last bit you did.

 

You fill all the traps, plug the vent pipe and connect the test kit wherever is convenient and plug the rest.

 

TIP:  Some top access shower traps with a lift out "bucket" that lets you clean them from above will not withstand the test pressure and will pop out.  I had to cut 2 thin strips of wood to wedge ours down in place to get the pressure test to work.

 

Our BC wanted the test done to 100mm H2O but that is impossible, it will pump up to about 70mm the depth of seal of your smallest trap and any attempt to go further just blows bubbles through the trap.  They accepted that.

[Kelvin]

1 hour ago, Lincolnshire Ian said:

The test before the pipes get buried seems to be quite straight forward. Thanks for the help. 

The test at completion though, is a bit perturbing, do I fill up at the traps in the toilets/sinks etc, cap off the underground pipes in the inspection chambers, cap off the vent pipes on the roof and then pressurise?

Pretty much. It is a pia as there are a lot more exits to think about and plug up. Took me ages going around ours on a set of walkie talkies with the other half shouting no until I eventually got everything sealed up. Took a note of it all and when I got BC out I couldn’t get it to hold pressure! We eventually tracked it down to the air test kit. 

[garrymartin]

1 hour ago, Kelvin said:

We eventually tracked it down to the air test kit.

It's always the last place you look, isn't it? 🤣