Bath waste pipe layout

[LeonR]

We are in the process of renewing our bathroom, it is outdated and it also smells, there is obviously a problem somewhere along the lines!

The current setup is that there is a 40mm waste pipe going from the soil pipe to the shower tray and the sink waste is connected to that pipe in the middle.

Now, this is a problem....if you fill the sink up and open the plug, water will rush both ways down the waste pipe, means you get the waste come out the shower tray!!

Also our vent pipe is in the bathroom!! with some valve on it!!? (we are going to put that outside)

Not sure if there is even a trap on the shower tray.. its a mess anyway..I have no intention of fixing it, we will just replace it all.

First off, I was going to give the bath and the sink its own 40mm waste pipe going to the soil pipe, is that the better way to do this?

What do people do to try and keep a gradient on the bath waste pipe? I assume being 'flat' is a no no, as the water could sit in the pipe and drain back into the U bend?

 

[moggridgeplumbing]

Good idea to have separate pipes for basin and shower/bath to soil stack.

If you have a lack of fall from the shower/bath then you will need to raise it, or if you are able, drop the waste pipe down below floor level. The cause of the discharge from the basin backing up the shower waste is probably due to blockage, lack of adequate fall or incorrectly piped up.

 

[LeonR]

Cool, thanks! Good to know the plan is roughly correct!

Why would you use a vent pipe in the house? Is this a common thing?


And yeh I think there may be a small blockage somewhere in the 40mm pipe as you say. I will be glad to bin it all and start again!

 

[moggridgeplumbing]

Sorry don't know your setup, but down here you sometimes get them on ground floor bathrooms that are secondary to a main stack. They are fitted with an air admittance valve to stop gas smells entering the building and when the installation of an external stack is not practical.