Bath draining speed when toilet not plumbed

Hi all,

The bath / shower in our bathroom has never really drained properly, and often needs unblocking. I had a plumber come and look at it, but he said that it was because the waste had been plumbed wrong, and that it was not a job he wanted to get involved in. Since then we've just been using drain unblocked regularly to keep on top of it.

My assumption was that there wasn't enough angle / fall in the pipe and that it was getting blocked on a corner.

We are in the process of fitting a new bathroom so I have removed the basin and toilet. Since doing so the bath / shower has been draining completely normally and the water has been draining faster than the shower can fill the bath.

The toilet and sink have always drained fine. Does anyone know taking them out has improved the bath drainage? Or is it just a coincidence??

Thanks in advance for any replies!

Have you capped off the WC and basin wastes? If not try sealing them off temporarily and see if the problem returns.

Sound like it may be a vent problem or blockage.

No haven't been capped off, that seems like a logical first test for when I get home.

So if I cap them off and immediately get the same problem, am I looking at a ventilation issue?

Yes - cap the wc with a plastic bag and observe if it balloons or sucks in

Thanks both for your help!

Had a bit of sucking and blowing but not as much as I expected. I did also noticing a bit of gurgling.

Time to find a big ladder I think, unless anyone knows a method to unblock without?

Any blockage is unlikely to be in the stack, more chance of it being underground. Any inspection chambers nearby?

There is, about 3 or 4 meters from the stack. I've just run both taps through the bath and gone outside to check it and it appears to be flowing fine