Surface water to foul water drain?

Is it OK to reroute 3/4 of my roof's rain water down the foul water pipe instead of down the surface water pipe?

My top floor flat has a dual water drainage system - FW and SW. It has a double roof with a valley gutter between them, and two gutters at the front and rear behind parapets. Rain water from the centre valley and front gutters goes down drainpipes inside my flat to the rear gutter and then it all goes through the parapet down to ground at the back of the building.

The pipes are enclosed in massive plasterboard box sections running the length of the flat and are not only taking up lots of space, but develop leaks occasionally. When this happens, it's a real task to open them up, repair the leaks and then replaster and paint them.

The SW pipe goes right next to the FW pipe at the centre valley, and draining the SW from centre and front roof planes into the FW would mean I could get rid of half of the pipe.

I know it's a mortal sin to connect FW to a SW drain, but how about the other way around? Cheers.

Reply to
S lo
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Many older properties have only one combined drainage system for FW and SW. The idea of separating them for newer properties is that it cuts down on the sewage treatment works capacity required - because SW can go straight into a river without needing to be treated.

If you put SW into a FW system, it will get treated unnecessarily - but that is about all. Some water boards give a discount on your water rates if your surface water *doesn't* go into the FW system. If you currently get this discount, you'll no longer qualify for it if you do what you propose - and if the water board finds out! You're unlikely to end up in prison - for this at any rate!

Reply to
Set Square

20+ years ago, you could apply for an "easement" to allow this on new builds and alterations via building control. It wasn't automatically allowed, but nor was it always rejected. I'm not sure what the situation is now.

Andrew

Reply to
Andrew Chesters

A couple of years ago our BDC officer said it was fine to do it. He said that before they didnt allow it but as the water company automatically charge for surface water disposal and you now have to apply for the rebate that they felt it was now perfectly fair.

Sam

Reply to
Sam

I'm not an expert on such matters, but have been looking into similar things myself recently. I can't see anything in building regs which specifically says you CAN'T run SW to a FW drain, however reading between the lines I doubt it would pass building regs, if inspected - I doubt the water board would be too happy either. Building regs says surface water can run into a drainage system, whereby a rainwater drainage system: "carries the flow of rainwater from the roof to an outfall (a soakaway, a watercourse, a surface water or a combined sewer)...".

I suppose the biggest risk is the FW sewer overflowing in torrential rain.

Andy

Reply to
Pecanfan

That, and that it cost real money to 'clean up' the rainwater in the sewage system. Hence your waterboard would rather it went somewhere else. Quite reasonably IMHO. Thats not to say it is a viable option in difficult circumstances like the OP describes.

Reply to
Andrew Chesters

It is permissible, but only as a third choice, where the other options aren't "reasonably practicable".

Reply to
John Armstrong

Its depreacted - most BCO's will not allow it. However some may. Its not against regs per se, but it is a local issue.

Reply to
The Natural Philosopher

By your description of how this system has been plumbed, it would say that the sewer system to your property is not to be used as a combine system for both foul water and rain/surface drainage. Because of this, it sounds as though you're stuck with trying to find another appropriate route for the rain water system if you want to re-gain the space that it is taking up in your flat.

A visit to your local council office to find out more info' of what is possible might an idea though. You might get a surprise, you never know.

Reply to
BigWallop

The op could always replumb the existing pipe(s) using solvent weld (Which surely hasn't been used so far otherwise the thing wouldn't be leaking would it?)

Reply to
Zikki Malambo

specifically

Is this not clarified by point b.i. below that though - where it qualifies a sewer as "a surface water or a combined sewer" - i.e. no mention of a foul water sewer, so therefore it wouldn't meet regs?

Andy

Reply to
Pecanfan

I'm intrigued by the replies. We have only FW sewers and, in theory, soakaways (although I cannot find them). For various reasons I want to re-route the disposal path of my surface water so asked the local authority about discharging it into the FW system. A very firm 'under no circumstances' was the reply. Reason being that the FW system is designed to cope with only the FW and will not accommodate SW as well. They also pointed me towards the relevant legislation which promised very big fines (IIRC the maximum was £30K) for running SW into a FW system - this was about 4 years ago and I'm afraid I cannot remember the actual detail.

Richard

Reply to
Richard

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