Can Kitchen Waste go into a Drainpipe?

Hello,

We have recently "re-jigged" our kitchen so that the sink is now under the window looking out onto the back garden rather than at the side of the house. Unfortunately the drain is at the side of the house - I was going to take the waste down the inside of the back of the cupboards straight out the side of the house and into the existing drain. Unfortunately on the wall where the drain is are also a waste downpipe and a guttering drainpipe (I think these all go into the same drain underground). Can I cut our kitchen waste into the drainpipe as this is the first pipe in my way on that wall?

That probably doesn't make sense to anyone but me but any help would be appreciated!

Many thanks!

You can't put a waste drain into a rainwater drain unless the drainage system is a combined one

Well, the open drain that the sink used to run in to is the first in the line, then comes the cast iron stack that is concreted into the ground, then comes the drain pipe, this also is cemented into the ground. I assume as they are all in a line and the last two are permanent fixings that they run into the existing open drain underground?!?

Many thanks, could save me a lot of aggro!!!

You should at least do a water test to check they are all connected into a combined foul drain system before proceeding; or you could be breaking by-laws.

Hi Richard,

Many thanks for the help, this is probably obvious but to do the water test do you pour coloured water down both to see if they use the same drain. Is it as scientific as that or more complicated and will the BI need any official proof??

Thanks again!

Screwed said:

Hi Richard,
Many thanks for the help, this is probably obvious but to do the water test do you pour coloured water down both to see if they use the same drain. Is it as scientific as that or more complicated and

Click to expand...

Yes it’s a scientific as that; you can put some dye in the water if you’re unsure but if you do one at a time it’s unlikely to be necessary unless the system serves other properties. Lift the nearest inspection cover down the line & check they both pass through the same system; a little imagination with a hose may be required to get water into the down pipe unless you wait till it rains!

Although the 2 drain runs may be close together, it’s unwise to assume they both feed into a common system. Many older systems were combined but it’s more likely the sink waste is connected to a foul drain & the rainwater drains through a nearby soak away, particularly if you can’t find an inspection cover close by.

Screwed said:

will the BI need any official proof??

Click to expand...

Providing it is a common system, they won’t be interested, just make sure you connect into the stack in accordance with the regulations.

You need to lift some inspection chamber lids.

Find the one that water from the toilets flows through (lift the chamber lids and watch for flow when someone flushes the toilet).

If you have any reachable rainwater downpipes/gulleys pour water down one and watch which chamber it flows through.

You can tell which downpipe the water is flowing down by putting your ear to it (not recommended with Cast Iron on a frosty morning) and listening.

Foul and rainwater should be separate (but not always) and if separate the Kitchen must be connected to the foul drain - the same one as the toilets.

When you lift chamber lids make sure no-one falls down them - can be quite deep.