Bath slow to drain.

26 Nov 2007
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United Kingdom
Dear all,

Up until around a month ago I had a bathroom wash basin with 32mm waste pipe travelling vertically down the wall into a swept T. The swept T connected into a 40mm horizontal pipe run which ran for about 1m into an an original fitment stack pipe. The stack pipe and horizontal pipe run are around 40 years old. At the other end of the swept T was a 1 metre run in 40mm pipe to a bath and conventional trap. When I emptied the bath and basin simulatneously the basin would drain very slowly and the bath would also be very slow to drain, if at all and would sometimes gurgle.

I then removed the basin and noted that the 32mm vertical pipe was so full of crud that at the swept t area the internal bore of the 32mm pipe was around 10mm. I removed the swept t and fitted a new straight coupler with solvent fitting onto the existing 1m length of pipe into the stack. Perhaps in error I did not rod or clean out the existing 1m horizontal pipe between the new solvent coupler and the stack pipe. i then fitted a new length of 40mm pipe through two elbows into a new swept T (correctly fitted in the right direction to feed a new basin). I run a second length of 40mm pipe from the new swept t into a new bath which has the plug hole at the other end than the previous bath. The new bath is fitted with a new exofil square bottomed trap.

I have also fitted a high pressure shower into the new bath with Stuart Turner pump which delivers around 10-12 litres of water per minute. After around a 5-8 minute shower I am ankle deep in water as the bath does not seem to drain quick enough. There is no hair in the bath plug hole and the new square bottomed trap is not blocked when viewed from the bath i.e the viewable internals of the new trap look clean.

When I fill the new basin (which is down river of the bath) and then empty it, it seems to drain quickly regardless of whether or not the bath is draining. However if there is water draining from the bath at the same time as water draining from the sink, then the sink continues to drain quickly but the bath plughole splutters and gurgles. I cannot easily gauge if the bath water drains slower or at the same speed if the wash basin is draining.

The horizontal run from the new bath plug hole to the connection to the stack is around 2m in length and the vertical height between the bath base and the top of the connection into the stack is around 10 - 12 inches. i.e not much of a gradient.

I would greatly appreciate if anyone could advise on why the bath drains so slowly. I understand that I am clearly not draining water from the bath quicker than water is going in from the shower but I would like to know why this is.

The basin waste seems to drain quickly regardless of whether the bath water is draining or not and to me the bath always seems to drain slowly. I am thinking perhaps that the existing un-inspected and un rodded 40 year old connection of 40mm pipe between the existing stack and the new solvent coupler may have a blockage or partial blockage. Or alternatively there is a small gradient in the new horizontal run

Any response would be greatly appreciated !!

Need Help21
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Thanks for your help buddy, why would you suggest the partial blockage as opposed to the lack of vertical drop and long horizontal run combination?????

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your old pipes and a few years unblocking similar ;) They seem to " fur up" like arteries for some reason reducing the bore with soap+ hair etc. As you found . and it`s all along , I would expect. And gradient etc. doesn`t seem to have much effect on it , Unless you`re looking @ a real old waste pipe @ 45 degrees or so run into a hopper - where the water flies thru` so fast it doesn`t touch the sides :)

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