extra soil pipe?

[ineedhelp229]

Hi,
i live in a 1920/30s buillt 3 bed house. I have one soil pipe that connects to the toilet and runs into the manhole.
I also have another soil pipe that is about 8 foot away from the other. I have scanned the houses adjacent to mine and the one opposite and one else seems to have two?

Was this done to have an additional breather for the whole stretch of houses as if im correct in saying, all the houses connect to each other????

 

[ineedhelp229]

Ideally i would like to remove the pipe when an extension is built....that is why i ask... There is some point to my questions

 

[noseall]

I am of the opinion all separate dwellings require their own individual s.v.p.

But i'm a little unclear as to whether your saying you have two or one s.v.p.? Generally a single s.v.p. at the head of the drain is enough. Any others, particularly lower down the run and in close proximity, would be doing nowt.

However there can be a need to have more than one stack pipe in order to drain more than one toilet or sanitary elements.

Don't be fooled into thinking an air admittance valve is enough because it is not. If all the homes on the street followed suit you would be in a pickle.