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CuriousCat

In blocks of flats, is it normal for all the toilets to share a single soil stack / SVP?
So if there is a blockage in the lower part of the SVP, what is to stop the sewage backing up and overflowing from a lower flat's toilet?
All the sewage from the flats above would keep flowing down and the lower flat toilet would act as an 'overflow'.
I can't find anything regarding this when searching online.
Surely it would be sensible to have one SVP per flat? That way, there is no pressure of sewage downfall from flats above.
Many thanks.
 
Cost, convenience and aesthetics I'm afraid.

So is this standard practice?
Does it depend on the age of the block of flats?
What about valve systems to prevent sewage backflowing out of toilets?
 
So is this standard practice?
Does it depend on the age of the block of flats?
 
Unless you were going to have separate sewers for every flat, whats the difference? They have to join somewhere.

One of the issues with a flat is that you share some common parts with your neighbours - even if its just the roof.
 
Unless you were going to have separate sewers for every flat, whats the difference? They have to join somewhere.

One of the issues with a flat is that you share some common parts with your neighbours - even if its just the roof.

Yes, your right there. I take your point that if the sewer blocked beyond the SVP, then you could get a back up of sewage affecting every toilet draining into that blockage. But would a sewer produce such a water tight system, so as to allow the blocked sewage to back up against gravity?

With flats you have the effect of flats being higher up and so gravity can force sewage out of a lower flat's toilet.
But with houses on a street, apart from the toilets being upstairs only, I'm guessing this force of gravity is going to be less?

Sorry if I'm not explaining this very well!

So in your experience, is this a common problem in flats, as opposed to houses?

Thanks
 
Peak flow rates ect . 10 flats with 15 occupants In each will need 9" vertical drop. 10 flats with 1 occupant = 4" drop or if m&e designer feeling flush 6" will be driven by minimum
 
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most new builds ive been on in the last few years the ground floor flats are direct to drain everything above shares a stack that way the manholes pop before the ground floor is flooded
 
In blocks of flats, is it normal for all the toilets to share a single soil stack / SVP?
So if there is a blockage in the lower part of the SVP, what is to stop the sewage backing up and overflowing from a lower flat's toilet?
All the sewage from the flats above would keep flowing down and the lower flat toilet would act as an 'overflow'.
I can't find anything regarding this when searching online.

Surely it would be sensible to have one SVP per flat? That way, there is no pressure of sewage downfall from flats above.
Many thanks.

And in a 30 story block of flats that's 30 S&V pipes, if it's 1 per floor, to wrestle to the ground floor and make individual connections in to chambers.
So you either need a large service duct or the bottom flat will have 30 pipes passing through it.
If you want 1 per flat it could be hundreds.

And re blockages, I do commercial buildings and have seen relatively small plugs of grease and paper hold back hundreds of gallons of sewage in chambers up to 5 mtrs deep.
 
most new builds ive been on in the last few years the ground floor flats are direct to drain everything above shares a stack that way the manholes pop before the ground floor is flooded

Thanks for the info. I know someone in a three storey block of flats and this is the set up there.
In this case it was the first floor flat that got flooded with sewage. The blockage was in the SVP draining the middle (first) and upper (second) floor flats.

The blockage in this case was "upstream" of the manhole and blocked enough to support all the sewage backing up as high as the first floor flat.

The guy in the top floor flat was unaware of the blockage and so carried on using his toilet and waste. So this all overflowed into the flat below.

The toilet in the ground floor flat was draining normally, because as in your experience, it had it's own SVP.

If the top (second) floor flat had it's own SVP, then this flood would not have happened.

In your experience, how common is this problem in blocks of flats?

Thanks again for your reply.
 
And in a 30 story block of flats that's 30 S&V pipes, if it's 1 per floor, to wrestle to the ground floor and make individual connections in to chambers.
So you either need a large service duct or the bottom flat will have 30 pipes passing through it.
If you want 1 per flat it could be hundreds.
.

Thanks. I take your point. It would be unfeasible in large buildings of that size.
I guess a more realistic precaution would be to fit wider SVPs.
 
Yep and it knocks you off benching and on to saftey chain as you clear it!
 
one of my last jobs before I left brum was exactly this scenario ground floor council flat 6 storey
spewing out brown stuff all over bathroom floor our firm only done day cover for solihull council night cover by others this clown turned up during the night removed toilet and guess what happened he then ran into tenants bedroom whipped off their quilt and used it as a dustsheet he also rammed one of their pillows up the soil pipe to stem flow we had one dirty day but cleared blockage very easy climbed on roof and rodded away it went did feel very sorry for tenants they were an oldish couple and did look after their place..brum
 
one of my last jobs before I left brum was exactly this scenario ground floor council flat 6 storey
spewing out brown stuff all over bathroom floor our firm only done day cover for solihull council night cover by others this clown turned up during the night removed toilet and guess what happened he then ran into tenants bedroom whipped off their quilt and used it as a dustsheet he also rammed one of their pillows up the soil pipe to stem flow we had one dirty day but cleared blockage very easy climbed on roof and rodded away it went did feel very sorry for tenants they were an oldish couple and did look after their place..brum

So what was the SVP drainage in this six storey block?
Did all six flats share the same SVP?
 
yep..brum

So that was a lot of sewage down pressure...!
Is this a common problem in flats, in your experience?
Do you or would you live in a flat with this system?
Is there any type of valve system that can be fitted to prevent this type of thing?
 
So that was a lot of sewage down pressure...!
Is this a common problem in flats, in your experience?
Do you or would you live in a flat with this system?
Is there any type of valve system that can be fitted to prevent this type of thing?


I'm sure McAlpine make a one way valve in 110mm but think the idea is to stop vermin entering the property. Not too sure on how much back pressure it would hold, it's probably just plastic?
 
I'm sure McAlpine make a one way valve in 110mm but think the idea is to stop vermin entering the property. Not too sure on how much back pressure it would hold, it's probably just plastic?
Was going to say that but feel that these rodent protectors would not help as stack would still fill if there was a blockage at bottom of stack luckily this has only happened once to me..brum
 
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