Building over a drain/sewer inspection chamber

Parradona

We are looking to purchase a house in Merton on a long straight road consisting of blocks of terraced housing built around 1933. We anticipate that we would like to add a single level extension onto the rear of the property in the next ten years, however there is a single inspection cover for what seems to a combined foul and drainage sewer around 6ft from the rear of the property.

Having received the water and drainage search results from Thames Water, it is clear that such sewers run in a straight line along the back of the row of properties and are in similar positions on the back of the majority of the other properties on the street. There is also a sewer/inspection chamber in the same straight line of sewers in a public alleyway, just over one house width away from the property we are looking to purchase. Finally having looked on google maps , it is evident that many of the properties in the row of houses along the street , already have added extensions to their properties and in many cases they are on properties with similarly located inspection chambers.

Based on the information above, we don’t think that the inspection chamber in the properties back garden will stop us from building an extension, but want some advice prior to completing the purchase of the property.

We presume that we’ll be able to get building over permission if we do need to extend over the chamber and hope that the fact that the sewers are in a straight line along the back of properties make blockages and problems highly unlikely? The fact that an inspection chamber that is in a public alleyway, seems to be within a fairly short distance (approx 10m), may also mean that if any rodding is ever required, this could be the first access point as opposed to the chamber in our rear garden.

Any advice would be much appreciated, be that in terms of any likely additional costs, procedures we will need to follow and/or the likelihood of any problems.

Tucker

I have just built over my waste pipe, so that side of it is no problem provided you do it correctly with lintels etc.

The inspection chamber will depend on the building inspector and one factor will probably be the location of the next chamber the other way from the alley.

I had to move mine out of the build and reposition it on a area of patio that wasn't being built on. Is there an area in line where it could be sited? Can the new build be a couple of feet less than your boundary to allow it to stay on your land in a new position?

I moved my own, so it's not a big job, just slightly fiddly.

ormus

assuming the chamber is only for your property, then its usually ok to build over and use a double sealed cover.
make sure you can access the cover fairly easily. ie dont concrete over it!
otherwise its a matter of moving the whole chamber. with any associated costs of course.

stef73

We built a extension over our 1900 terraces rodding eye there was no problem. My neighbour asked about building over a access hatch and was told there would still have to be access as its a section 24 sewer . Does the sewer serve only your house or the whole terrace ? . If it is for the whole terrace have you looked into section 24 sewers ? . If your house / drains were built before 1937 then and they serve more than 1 house your utility provider is responsable for upkeep and maintenance of them and if you re-route them my neighbour has been told it couuld become a grey area as his bit could be classed as a new sewer .

keystone

It is a requirement that a manhole / inspection chamber is fitted whenever an additional soil outlet joins the sewer.

It is likely, in this case and as you have suspected, that all the outflow from the terrace flows down this sewer. As the property was built in 1933 then this is a public sewer and guess what you do not own it or have responsility for it. The upside of that is that any blockage or repair work from that manhole (as far as you are concerned) has to be done by Thames Water at their cost. You are responsible for your own pipework as far as that manhole. Thames also own the cover BTW.

SO yes the cover must be double sealed but it MUST be accessible in the future so you'll prolly need Thames Water's seal of approval on your plans.

Cheers

babyblooz

This is very interesting! We share an sewerage pipe with our neighbours and I always thought we were responsible because it went under our garden!

keystone

babyblooz wrote: »

This is very interesting! We share an sewerage pipe with our neighbours and I always thought we were responsible because it went under our garden!

If your property was built after 1937 you'd be correct!

Cheers

babyblooz

Hmmm, we were told our house was built in 1936!

keystone

babyblooz wrote: »

Hmmm, we were told our house was built in 1936!

In which case its your responsibility to the first manhole where it joins the outfall from a neighbouring property. After that point its classified as a public sewer and is the responsibility of the local water authority.

Cheers

babyblooz

The drain runs across the bottom of our garden from their outside toilet and joins in the sewer pipe about half way across the width of our garden, where there is a manhole cover which we have covered with decking. Their outside toilet gets used, it builds up and backs up so we have to put the rods down from our man hole cover to clear it. It hardly seems fair that we have to keep hauling up the man hole cover and power hosing their smelly stuff away!!! We don't cause the blockage but we have to sort it.

stef73

babyblooz that was what happends to our house , the blockage cause problems for us not for the person who blocks it . I paid homeserve for over 12 months then when it blocked they came out and said they couldnt unblock as it wasnt my drain that was blocked . The drain man unblocked it for me but told homeserve he didnt . He then told me about section 24 sewers so if your house is 1936 it should come under this . I emailed united utilities (my waste water company) explaining to them i had a problem with a section 24 sewer . They emailed me back saying yes it was and they were responsible for it . They gave me a phone number to call and a contact name and when it blocked again they came out cleared it then sent down a cctv to check the sewer . If it blocks again all i have to do is call them and it gets unblocked .