water backs up shower waste when bath emptying + bad smell

[tan8856]

So it looks like the plumber who fitted our bathroom about 3 years ago stitched us up. For whatever reason he didnt make the waste pipes steep enough so for example the shower waste goes straight off at almost a 90 degree angle and always has about 1cm of water sat in it. im not sure how that is even possible, i guess there must be some sort of build up of muck at the end of that part of the pipe that prevents the water from flowing away? or could the pipe even be not quite horizontal?!

This whole situation isnt a problem when the shower is used but every time the bath is emptied the water backs up into the shower (sometimes quite badly) along with some black sludge and the smell of rotten eggs. we do get a black slimey sludgy build up in our bathroom wastes/pipes.

The bathroom has a tiled floor and I dont want to get the shower tray lifted to see whats going on underneath, so how else can i stop the sludge/smell? i bought a drain snake - a cheap handheld thing about 1m long and have wiggled that in the pipe today. will that work? what else is there?

thanks

 

[Madrab]

What are the levels between the shower and the bath? Is the shower lower than the bath? Sounds like the shower is plumbed into the same waste pipe run as the bath and you are getting back flow into the shower when the bath is emptied. May be down to a blockage further down the run.

Has this just recently started? Or have you always had glugging/bubbling noises come from the shower when the bath is being emptied?

 

[tan8856]

hi

the shower and the bath are on the same level and i believe they drain into the same waste pipe

as the plumber left he said to me 'oh and if you get water backing up into the shower dont worry because thats quite normal' and i remember thinking 'i bet it isnt normal!'

the water has always gurgled when the bath empties (both the sink and shower gurgle) and over time the smell and backing up gets worse. i then chuck a liter of bleach down the shower waste and let it stand for an hour and that improves things but the backing up and smell seems to be happening more often these days. we get black rubbery gunk in the pipes, i think there may be a build up of that further down the waste that doesnt help the backing up.

whats the best way to clear it?

 

[Madrab]

OK, first things first, if you find the others are gurgling then there is a syphoning effect being created by the bath being emptied and the volume of water traveling down the waste pipe. That causes a vacuum in parts of the pipe and sucks the water out of the trap, that then lets the smell of the drains into the bathroom.
Best way to clean out the gunk its getting to the pipework and physically cleaning it out. Otherwise it's down to chemical or pressure cleaners.

No the gurgling from the shower & basin when the bath drains, should not be considered as 'normal'. With the correct waste design it should not happen. If three appliances are using the same pipe, especially with a bath, 50mm waste pipe should really have been used. Also Anti Vac traps and/or vent could be installed to avoid the traps on the basin and shower being emptied. Consideration could also be given as to where in the pipe run each appliance feeds into and the fall in waste pipe as it seems you are getting standing water somewhere and the bleach is cleaning out the gunk that collects temporarily.