Extension built over manhole

Snoookems

I just had a local authority building regs representative come over (for other stuff in the house). She looked at the drains and said we should inform Thames water but doesnt think they will make us dig a new hole outside to move the manhole. She suggested just double sealing it internally will be sufficient. Sounds ...more positive? I called Thames water too last week but they had no records of this pipe as its on private land. They only can see there's a pipe running outside our house.

Davesnave

Snoookems wrote: »

She suggested just double sealing it internally will be sufficient. Sounds ...more positive? I called Thames water too last week but they had no records of this pipe as its on private land. They only can see there's a pipe running outside our house.

Better late than never for the info!

Yes, a screw-down, air tight inspection cover will be adequate to seal the conservatory from the drain, whilst still providing access.

If Thames do not have a detailed record of the pipe, are you sure it belongs to them?

And do you know if it's carrying other waste, besides that from your house?

Snoookems

I believe yes, I will try to get my neighbour to flush and see if comes flows through. These mysterious things..... I gotta say for all the poo that goes through the pipes look rather clean and odourless!

Angie_B

Thames Water usually have a no-go on manholes within properties. The manhole should have been removed and piped through, with a rodding eye external to the conservatory/extension. They even say no to double-sealed manhole covers usually.

Read their guide here:

https://www.thameswater.co.uk/developers/693.htm

I'm not sure what you can do if it is already done but my first thoughts would also have been indemnity against Thames Water finding out and making you change it.

Furts

Davesnave wrote: »

Better late than never for the info!

Yes, a screw-down, air tight inspection cover will be adequate to seal the conservatory from the drain, whilst still providing access.

This is correct but may lead people to believe that it is a solution when it is not.

If Thames Water own the manhole - and OP now appears to doubt this - then they require access to it. This is difficult when it is located in an extension. Further if there is a blockage and it backs up then instead of overflowing the garden the contents will be discharged within the home. In order to clean, maintain and jet or rod then equipment will be trailed into the extension. There also needs to be room for a winch to get into the manhole if it is confined or deep. Finally there is an overwhelming possibility of sewage, or debris, being created within the extension as a result of work.

A double sealed cover does nothing to alleviate any of these scenarios. A properly diverted drain answers all these scenarios.

Davesnave

Furts wrote: »

A double sealed cover does nothing to alleviate any of these scenarios. A properly diverted drain answers all these scenarios.

I bow to your experience, as mine is limited.

The only bolt-down cover I ever installed was in my elderly father's garden. There, because of poor drainage work on a relatively modern estate, the sewer would block with annoying regularity, blowing the inspection cover and sending sewage cascading down his garden.

I don't know all the details, but my poor Dad was unable to get a sympathetic ear from anyone, probably because it was a private, unadopted drain.

Anyway, I installed the cover and, within a short time, someone with more clout than Dad had the sewage in their garden instead. Once this had happened a couple of times, 'something' was done and the problems ceased.

So it worked for me.

But no, I wouldn't want a drain cover of any kind in my house. Conservatory perhaps, but it would depend on the exact circumstances.

southcoastrgi

if it serves your neighbour as well it is now a shared drain & the responsibility of the water co, private land or not