I see a lot of "leaky-dam" and water collection groundworks in such estates recently. Is that for road run off and roof run off? Is there national outlawing of roof run-off into the sewer system these days or is is it down to local planning offices?
I thought it was national policy.
Since about 1970. Building regs part H3:
3) Rainwater from a system provided pursuant to sub- paragraphs (1) or (2) shall discharge to one of the following, listed in order of priority:(a) an adequate soakaway or some other adequate infiltration system; or, where that is not reasonably practicable, (b) a watercourse; or, where that is not reasonably practicable, (c) a sewer.
Theo
The standard policy is that a SUDS assessment has to be made for any new development. That has the hierarchy of:
1) Soakaway within site (best) 2) Drain into local watercourse 3) Drain into surface water sewer 4) Drain into combined sewer 5) Drain into foul sewer (worst).None are banned as such, but a developer (or even a single self builder) will need to demonstrate why the better options are not viable. A simple example is that soakaway wont work in clay soil.
Options 2-5 will in likelihood be required to have some attenuation to reduce run off to something like greenfield rates, or at least no worse than before the development. The ponds you see are simple means of attenuating the water flow - ie outfall is throttled by a small diameter outlet pipe.
yes
yes
No. It's in the building regulations
Typically yes.
I don't think its outlawed as such, but there are a list of preferred ways of handing surface water and run off, and dumping it into the sewer system is the least preferred.
Does depend a bit on the area... where I grew up (established 19th Century built estate) they had combined sewers, and clay soil, so it was accepted by building control that is where surface water would be dumped.
Next house, (1950's estate) did not have a combined sewer, still had clay soil, but also had a separate surface water "sewer" that discharged into a local stream, so building control would require you use that rather than the sewer.
Yes thanks for that. A related query I cannot find a Google answer to. For old housing stock where the roof down pipe connects into to the foul sewer system. Is there a device or recognised named process like the interceptors for filling rain butts, but for diverting extreme rainfall out to French drains/soakaways/general garden, passing any "normal" rain normally? After all the gardens would be deluged anyway. So if adopted widely, avoiding overcharging the local foul sewer choke-point of the lamphole connection between local high level sewer system into the wider area deep sewer system.
The moment you touch it it becomes a 'material alteration' and building control can insist you build a soakaway.
One of the extreme problems with building control is that you can repair back to original, but you cannot modify unless the modification meets todays regs. And then you have Grenfell towers, where they had to put enormous foam slabs on to meet current regs, and then cover it up so it didnt look horrid, with as it turned out, flammable cladding
sticking an inch of celotex inside, wouldn't have met regulations
Seems to be pretty random. Where you need to look is your councils planning web site. A lot of planning applications go into detail about where the run off water should go and how its handled, The word Sustainable seems to crop up a lot as does drainage that means no adverse effects on existing premises and infrastructure. One supposes then that this water automagically disappears somewhere? grin. Brian
If you had been around here, not my house as I'm on a hill, but in the lower lying places, you will know older housing shoved all the water down the sewer, and now you get sewage pushing up the covers and contaminating the land and flooding houses due to the lack of delay between the downpour and the stuffing up of the sewers which are very old and narrow and never meant to cope with the number of dwellings connected to them. Its policy now but too many are still connected, and built around the turn of the century. Brian
Don't think there is a standard domestic fitting like that - mainly as people are not going to pay to make the utility's life easier. Normally if you are going to go to that sort of expense you would want to store the water yourself and put the overflow into the sewer to maximise your own benefit. So a rainwater butt at the least, up to an in-ground greywater tank with pump for irrigation if you have cash to spare. Simple truth is that potable water is cheap enough not to bother with the capital expenditure of anything more than a water butt or a few 1m3 IBCs.
On a larger scale flow control is often done - e.g. a chamber with an orifice outlet (or hydrobrake). Good design makes sure that any resultant flooding due to backing up after an extreme event occurs in carparks etc (on your own land) being used as temporary flood storage and does not flood and property. You wouldn't want to build soakaways just for occasional use.
That explains why googling gets nowhere. Its a matter of mitigating/preventing a future local flooding with rain and sewage scenario coming up thru bog pans, rather than helping out the water utility company. I've taken photos with a torch, thru the air-balance vents of the local choke-point foul sewer manhole of the torrent of such run-off, where the local upper level joins , via vertical lamphole , the bigger low level main foul sewer system . Initially because of the noise from all the area's roof run off , in a cloudburst situation, but now more regularly, its when it goes quiet you have to worry as the level is rising in the manhole. It would require people with old houses, vast majority of the housing stock ,agreeing to install such devices , to protect the lower lying houses. But if the devices/process is not recognised, then as an idea its probably going nowhere , just because of that, let alone individual "wayleaves"
I think the process a rainwater diverter works is that in light rain the water trickles down the sides of the downpipe, where the diverter collects it. In heavy rain there's a lot of water and it goes down the middle of the downpipe and bypasses the diverter. Similarly if the water butt fills up, the water backs up the diverter and overflows into the downpipe.
My diverter currently has the pipe removed and in very heavy rain recently (gutters full) there was only a trickle coming out of the diverter.
If you wanted to divert heavy but not light rain, perhaps you could fabricate something like a scoop which sits in the middle of the flow and pipes off the majority, but leaves the sides untouched.
Kind of like an inverted plastic bottle in the middle of the downpipe, with bottle base opened to collect the rain, and the neck piped off to wherever. Supports hold the bottle in the middle so that rain can bypass it when running down the sides.
Theo
I think it would be a hard push to get residents to install some homebrew gizmo. Although the civil engineer in charge of a recently completed property protection marine flooding floodwall could not find off-the-shelf bypass reverse flow flap valves and got a local metal fabrication company to make some. Just a 2inch by 2 inch hinged stainless steel plate that allows any buildup of rainwater on the landward/house side of the wall to flow back riverward when any river flooding retreats, through the rebar reinforced core, 2 brick skin faced wall. Otherwise off-the shelf (over?) engineering design of floodwall, with deep footings that seemingly would stop a Chieftan tank .
'They' didn't have to do anything. It was part of NuLabs 'warmer homes' initiative. The outside of Grenfell had external pillars so using ridid board insulation was flawed from the outset. They should have used rockwool slabs with rockwool padding around the angular pillars. if they had, the initial kitchen fire would have either never have made it to to the cladding, or if it had the cladding would have burnt but been separated from the core of the building. Lining every internal flat (and some had been sold under right-to-buy) would have been highly disruptiv and far more expensive
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