Toilet waste drain

[Martyn Bell]

We are making changes to our 1950's bungalow lay out. We want to put a wet room including a toilet where there is currently a kitchen. My question is, can the existing kitchen sink drain (outside) be upgraded to accommodate the toilet without digging up the concrete patio to connect to the main sewer (running along the back of the property)? The existing toilet drain (located on a different wall) does not have a soil stack.

 

[Madrab]

A toilet needs to be run ideally in 110mm pipe from the back of the toilet to the main sewer connection/chamber where ever that may be. Without digging the outside drain and seeing if it's run to the main foul sewer it's hard to say.

 

[Martyn Bell]

Thank's for your fast reply. There is a gully on the kitchen wall outside, this is the rear wall of the property. The main sewer which joins from one neighbour to the other runs along about 4 feet from the rear wall under a concrete patio. Is there some easy way to tell if the gully has 110mm pipe?

 

[Madrab]

Chances are it will run into 110mm and it would be connected to the foul water system but you would need to determine whether you have a dual system or not, where the foul and rain water drainage is separate.

Do you have the original plans for the house? If not then it's time to uncover the nearest manhole and dye the gulley.

 

[Hugh Jaleak]

If the drain is taking the Kitchen sink waste then it should be connected to the foul sewer, but as Madrab says, a dye test will confirm this. (Not unknown for a drain to be cross connected).

If you can confirm the gulley does indeed run to the foul sewer, then next question is, how/where does it connect? You will need to be able to rod the run upstream to the proposed WC in the event of a blockage, so if existing run connects inside a chamber then no issue, if it's on a blind junction into the main sewer, then you will need to look at putting a chamber in somewhere along the run.

I'd think it unlikely to be anything smaller than a 4"/110mm pipe, but again this needs to be established. A CCTV survey if the pipe is accessible from downstream would determine the size and condition, often wise if planning to connect a WC to a drain that has hitherto been only carrying water.