Greywater waste pipe into new rainwater hopper downpipe

[granta2025]

HI

Just looking to understand what is allowed re: plumbing on a new 2 storey extension on an existing Victorian house. The sewer system is a combined foulwater/rainwater one.

Before the extension was built, there was a rainwater downpipe with hopper at first floor level that flowed down and onto the lower ground kitchen roof, downpipe into gully. For the new extension, the rainwater pipe has been extended upwards 2 storeys with a new hopper.
However, there is now wastewater flowing through this pipe, over the roof and into the gully. So I assume that the builders have joined a waste water pipe to the rainwater pipe.
Is this allowed under building regulations?
I live in the downstairs property and am concerned about the waste water flowing over the roof and also responsibility for any blockages in the gully when previously it was a rainwater only gully.
Thanks for any advice.

 

[Hugh Jaleak]

Hoppers for Wastes are only permitted now as a direct replacement for an existing arrangement. It is not permitted to install a new waste discharging into a Hopper, and especially one that is discharging over a flat roof!

Any new waste, if it cannot be routed to a stack, must be taken directly to ground level in sealed pipework, upsizing as necessary to prevent siphonage, to then either connect directly to the drain or enter the drainage system via a trapped Gully.

 

[granta2025]

Hoppers for Wastes are only permitted now as a direct replacement for an existing arrangement. It is not permitted to install a new waste discharging into a Hopper, and especially one that is discharging over a flat roof!

Any new waste, if it cannot be routed to a stack, must be taken directly to ground level in sealed pipework, upsizing as necessary to prevent siphonage, to then either connect directly to the drain or enter the drainage system via a trapped Gully.

Thanks, that is what I had thought form my reading of the building regs but was wondering if there were any exceptions. There is a central stack pipe and I don't know why the builders haven't routed the waste pipe internally to connect with this.

If that isn't possible, then they would have to run a new downpipe and dig up my garden to install a new drain? This is all at the back of the house.

 

[Hugh Jaleak]

Thanks, that is what I had thought form my reading of the building regs but was wondering if there were any exceptions. There is a central stack pipe and I don't know why the builders haven't routed the waste pipe internally to connect with this.

Possibly as the external run is easier, cheaper and/or they're unaware of the Regs. Or just arrived on Horseback

If that isn't possible, then they would have to run a new downpipe and dig up my garden to install a new drain? This is all at the back of the house.

Depends what other options there are, is the existing gully taking the downpipe suitably accessible?

 

[granta2025]

Possibly as the external run is easier, cheaper and/or they're unaware of the Regs. Or just arrived on Horseback

Depends what other options there are, is the existing gully taking the downpipe suitably accessible?

The existing gully is quite small and currently holds the rainwater drainpipe from my kitchen extension roof. No space for any further pipes. Plus not keen on having any digging in my private garden to install a new drain, and might need freeholder consent.

Any advice on best course of action now? The flat owner is unresponsive to emails and the builders don't speak English so I can't ask for any info from them. Should I call building control to check if it's allowable?

 

[Hugh Jaleak]

Yes, I'd go to Building Control (as it's against regs), and see if Environmental Health will also have a look. Its not going to be very sanitary, especially this time of year if waste water is pouring onto the flat roof and drying out.

 

[granta2025]

I will give them a call.

Just to clarify, the roof on my extension is sloping.

 

[Hugh Jaleak]

Just to clarify, the roof on my extension is sloping.

Doesn't matter, it's still not correct. Hoppers were banned for Wastewater years ago as they are horrible, unsanitary things, and no way should grey water be allowed to run down a roof to another gutter.

 

[granta2025]

Doesn't matter, it's still not correct. Hoppers were banned for Wastewater years ago as they are horrible, unsanitary things, and no way should grey water be allowed to run down a roof to another gutter.

Just an update - I've sent photos and spoken with Building Control. They inform me that the applicant is using a private building control company [i did not know these existed until just now!] and so have to refer the matter to them as they don't have power to intervene.

Interestingly, they said wastewater technically only refers to toilet waste and bath/basin water is allowable through the rain pipe, though he had concerns about the flow capacity from bathwater (though I don't think they have installed a bath here).

His main concern was about soap suds etc flowing openly on my extension roof so here's hoping the private building control see it this way.

 

[Madrab]

That's surely got to be misinformation - Waste water as defined by DEFRA and by the UK gov EH is made up of any water that has been used domestically/commercially/industrial and then discharged into the sewerage system. This is made up of and defined as - Grey water - Black water and Septage
Grey - is created by washing/cleaning/cooking etc -
Black - which is specifically toilet outflow
Septage - which is outflow from septic tanks.

https://assets.publishing.service.g...e2_Understanding_Wastewater_Session_Note5.pdf

https://assets.publishing.service.gov.uk/media/5a799210ed915d0422069741/pb6655-uk-sewage-treatment-020424.pdf

I would want clarification and documentation confirming that Basin/bath/shower etc isn't classed as waste water. Waste water from baths/basins/showers or anything else like that should not be discharging over a roof, that just isn't right in any book or any way it's looked at IMO.

 

[granta2025]

That's surely got to be misinformation - Waste water as defined by DEFRA and by the UK gov EH is made up of any water that has been used domestically/commercially/industrial and then discharged into the sewerage system. This is made up of and defined as - Grey water - Black water and Septage
Grey - is created by washing/cleaning/cooking etc -
Black - which is specifically toilet outflow
Septage - which is outflow from septic tanks.

https://assets.publishing.service.g...e2_Understanding_Wastewater_Session_Note5.pdf

https://assets.publishing.service.gov.uk/media/5a799210ed915d0422069741/pb6655-uk-sewage-treatment-020424.pdf

I would want clarification and documentation confirming that Basin/bath/shower etc isn't classed as waste water. Waste water from baths/basins/showers or anything else like that should not be discharging over a roof, that just isn't right in any book or any way it's looked at IMO.

Thanks for the link and I agree, this was always my (lay person) assumption! I read the Building Regs Part H and there isn't much mentioned about the hopper or it being banned for waste water so any pointers on legislation would be helpful.

I think I will wait for the council BC person to get back in touch once he hears from the private BC person and see what they say about whether it is allowed. If they say it is allowed as this type of waste water is ignored, then I will challenge and ask for confirmation in writing.

As well the issue of wastewater flowing openly on my roof, I am concerned about the flow capacity of the gully with taking rainwater (esp in heavy rain) as well as domestic wastewater. I don't know if that is in Building Control's remit.

I wondered if the applicant might try to get round the open wastewater issue by asking to install a pipe going over my roof? Would I have to agree to that?

 

[Madrab]

I wondered if the applicant might try to get round the open wastewater issue by asking to install a pipe going over my roof? Would I have to agree to that?

Certainly up here, north of the border, you would need permission to install anything on a neighbours property, couldn't say for sure down south as the regs can have subtle differences.

 

[Hugh Jaleak]

If it helps to quote the Regs, the Building Regulations in England, Part H, Covers foul water drainage and disposal.
( https://www.gov.uk/government/publications/drainage-and-waste-disposal-approved-document-h )

Section 1.7 Branch Discharge Pipes.

'Branch discharge pipes should not discharge into open Hoppers.'

 

[granta2025]

If it helps to quote the Regs, the Building Regulations in England, Part H, Covers foul water drainage and disposal.
( https://www.gov.uk/government/publications/drainage-and-waste-disposal-approved-document-h )

Section 1.7 Branch Discharge Pipes.

'Branch discharge pipes should not discharge into open Hoppers.'

Thanks. I had read that before I spoke with Building Control but then got derailed by his comment about the definition of wastewater! I think this is where I need clarity on from them as that will underpin what decision is made.

The inspector is in the process of arranging a site visit with the developer so hopefully he won't like what he sees. If not, I will ask for why the current arrangement is allowable under Building Regs

 

[Madrab]

I think this is where I need clarity on from them as that will underpin what decision is made.

To me, the documentation from the governing bodies clearly define what waste water is, regardless of what a resource @ BC may think they know, that's the point of the documentation, so there is no ambiguity.

Unless there are specific bylaws in place then those documents are what the LA would need to follow, unless they have been superseded.

so hopefully he won't like what he sees

If you're not happy and don't want this, please don't be shy in pressing your point (without being terse or obnoxious of course) citing the documentation/regs, otherwise the developer could railroad over it if it is a grey area and the inspector is a private (& paid for by them) resource. If outcome still not agreeable then there should still be recourse back to the LABC.