Regulations re venting of WC and rodding access

[Bonce]

Hello All,

Apologies but I have been pouring over part H and read quite a lot of posts here but I don't understand the regulations regarding venting for WC's and also requirements regarding rodding.

If anyone can spare the time to give me an answer much appreciated.

Currently I have an upstairs toilet in my property that connects to a SVP and then runs to what ill term as a 'public sewer'. This is a drain line that runs down the back of my property and neighbours and so on down the street. Its a single drain and each property has a manhole at the back where each of the SVP connect into this.


This is all fine but I am planning an extension which would require current manhole to be covered. I believe I am right in saying that the sewer is termed 'public' (because it serves more than just my property).

I think I am right in saying therefore that I couldn't just leave the manhole where it is and allow access to it from the extension covering this bit. This would be a garage/work room anyway so it wouldn't bother me to have a manhole in the floor. Presumably due to the fact that I could be away when access is needed to the manhole.

What I don't understand is that surely I could argue that the main drain could be rodded from the neighbours up the street or down the street (rodding against the flow). The only part of the drains that wouldn't be accessible because of this manhole being 'unavailable' would be the connection betweeen the main drain and my SVP. SO basically my question is. Have I been told wrong or misunderstood regs?

2nd question as part of extension planning on a downstairs WC. If I was to make a connection at the same manhole would this negate the need for me to have some form of venting on the new toilet or would i still require something like a sub stack with an AAV?

As you can tell I'm a bit confused - never knew drains were so complex!

Sorry for long post and thanks in advance for any advice anyone can give.

Bonce

 

[Hugh Jaleak]

Basic rule of drainage is that all sections of the drain must be accessible for rodding should need arise, the manholes are there to provide access when needed, covering them over is not advised!

Highly doubtful you'll be allowed to 'lose' the manhole, as the drain is shared it now falls under the Water Authority remit, (and I doubt they or the Building Control Officer would be impressed with that idea...) Whilst access can be gained from the chambers either side in your neighbours properties, access will still need to be maintained to the lateral connection for your stack. Blocked drains also tend to leave large deposits of solid matter on the benching in chambers, need to be able to inspect and wash down as required after clearing a blockage.

If the manhole cannot be moved outside the new building line, then the usual practice when a chamber has to be put inside a building is to fit a sealed cover. The new ground floor W.C. can be connected directly to the drain provided the distance between the crown of the W.C. trap and the invert of the drain is no greater than 1.3m.

 

[Bonce]

Thanks Hugh Jaleak very much appreciated. Sorry took me so long to respond and say thank you its been a busy week!

 

[Hugh Jaleak]

No worries and know the feeling!