Is it ok to combine my en-suite wash basin and shower waste ?

Usually if shower waste pipe runs beneath basin you come off vertically for the basin by using a 40mm tee juction in the run & then reduced down to 32mm for the basin.

 

hi
best practice is to always use separate waste pipes, going to a gully.

i think its a reg. if going to a soil stack

can make it very difficult to unblock with tee's installed in pipework

regards
peter

 

Agree, seperate is best.

But, there are times when this can't be achieved.

Looked around a few should houses a few months back & they tee basin into the bath or shower waste pipe.

And I'm not sure with regs regarding stack, didn't look at that.

 

One problem with combining them is the suction that can occur when a bath empties or a shower runs for a long time - it will pull the water out of the basin trap. Mine was installed this way previously and it was a regular occurrence. It was normal after emptying the bath, to then run a basin tap for a few seconds and then a bath tap to ensure both traps were full. I have since re-fitted the bathroom and then are separate - with no suction or trap emptying problems.

 

My bath and basin are combined and never any problems.

 

Have combined them for the last 30 years or so, without problems.

 

It will depend on the length of the pipe runs whether you have a problem or not. I've combined many times without an issue, just increase the final pipe size to 50mm and make sure you have a fall on the pipework - then it will be fine.

 

Agree.

With a shower I would use 50mm pipe minimum anyway.