Do I Need a Manhole or an Inspection Chamber or Neither?

[NibowUK]

I have just purchased a victorian terraced property which still has an outdoor toilet approx 2m from the rear of the property. The local water board has confirmed this pipe runs the length of the garden (approx 20m) and connect into their main sewage pipe. THIS IS THE ONLY FOUL DRAINAGE on the property, there is no manhole, inspection or access chamber - NOTHING!

I intend making the rear most ground floor room into a bathroom with the toilet on the outside wall. I will also obviously have waste from other bathroom items and the kitchen (which previously just ran into a hole in the garden - Yeah, I know!).

I realise I will need to have a soil stack installed and obviously a connection to the existing underground pipe, but my question is this, MUST I HAVE A MANHOLE BUILT in between the soil stack and pipe or will a plastic inspection chamber (say 450mm), be sufficient to satisfy any legal or build reg' requirements.

I have contacted 3 different plumbers and they are all full of "ooh"s & "uummmm"s, but no answers.

Obviously I'm on a budget and on the face of it a plastic IC seems to be the easiest and most cost effective way to go, but can I do this?

Any help would be much appreciated.

 

[Hugh Jaleak]

Firstly, there's nothing unusual about the existing setup, Victorian drain layers were craftsmen, and to test a run, they rolled a ball through it. I'd like to see how many more modern drainage runs would pass that test! Bear in mind, when the place was built, it would have had an outside privy, and possibly a stone sink in the kitchen, with a cold water tap, nothing else. (If you wanted a bath, it was a tin bath in the middle of the kitchen floor!), so a single drain taking the flow from the WC and a kitchen gulley was often all that was needed. (My property was the same, the only chamber I knew of was 20 houses away, in the track at the end of the block, where the drain turns 90° to head into the rod! I relaid all my drains back to the main sewer, and provided chambers as required.)

A 'manhole' and an 'inspection chamber' are technically different. Manholes are large enough for personnel to enter the chamber, and work within if need be. Inspection chambers are small pits or chambers at points in the system to allow the system to be inspected, and provide access for rodding, jetting etc., if required. You need an inspection chamber, and yes, a plastic version will be perfectly adequate. Personally, I'd probably fit one at an appropriate position onto the existing salt glazed drain, making sure the outlet allows a straight run out along the existing drain, and then redo everything from the new chamber up to the house in plastic. If you use a bottle gulley for kitchen wastes and/or any rainwater pipes that need picking up, these allow the outlet pipework to be rodded from the gulley if need be so can be connected on a blind junction to the main run.

Building Control will need to inspect/approve the alterations to the drainage system. Any further questions, please feel free to ask.

 

[Newboy]

What size chamber will be determined by the invert depth - the deeper the invert the larger the manhole/access chamber (in general!)

 

[NibowUK]

Firstly thanks for such a comprehensive answer Hugh much appreciated.

You need an inspection chamber, and yes, a plastic version will be perfectly adequate. Personally, I'd probably fit one at an appropriate position onto the existing salt glazed drain, making sure the outlet allows a straight run out along the existing drain, and then redo everything from the new chamber up to the house in plastic. If you use a bottle gulley for kitchen wastes and/or any rainwater pipes that need picking up, these allow the outlet pipework to be rodded from the gulley if need be so can be connected on a blind junction to the main run.

This was my original thinking, but then that ever present oracle of knowledge 'a man in the pub' told me that legally??? I must have either a manhole or a manhole AND an inspection chamber. However an inspection chamber alone would not be 'legal' as he called it.

I spoke to the council today but they would not offer any guidance without a visit to the property and the appropriate consultation fee, My main fear is obviously when i get the building inspector in he will say dig it all up start over but this time fit a bloody manhole!

 

[Newboy]

How deep is the existing sewer from external ground level?

 

[Agile]

I think that any foul drain modifications and any new toilet in the house or extension will need a Building Regulation application and approval.

Would be best to get an architectural technician who will know what is required and do the drawings you need.

 

[NibowUK]

How deep is the existing sewer from external ground level?

I'm going dig out around the existing pipe on Fri morning and will get back to you, but from what I remember it not too deep, I'd say less than 18"

I think that any foul drain modifications and any new toilet in the house or extension will need a Building Regulation application and approval. Would be best to get an architectural technician who will know what is required and do the drawings you need.

Thanks Agile, you're right of course but, unfortunately I'm one of those people who likes to know what's required before someone else decides for me and spends my money. Like I said I really am on a tight budget.

 

[Hugh Jaleak]

Forget the 'man in the pub', he is talking rot. I have been working on, in and around drains for the past 25 years. It seems you're trying to make this a lot more complicated then it ever needs to be!

Secondly, you can also forget a 'manhole' you're not deep enough, or have a big enough pipe to worry about those. All you need is an inspection chamber at a suitable point, to allow access to the outgoing pipe down the garden, (once it joins into the shared main sewer, it's no longer your responsibility anyway), and to any branches from the chamber towards the house. If you're clever enough to put up a sketch of the house, showing the existing drain, and where you require pipes to run to, or where there is discharge pipework from the house that needs picking up, then I will happily give you guidance on what you'll need to do. If you're desperately stuck, PM me via the forum and I'll try and help that way.

For what you want to do, then Building Control will probably be happy with a sketch of the layout, and then just do an inspection before you backfill.