New toilet help - advice

Hi all, a little openended this but here goes. Single storey house with one toilet. The toilet waste goes underground to a 'three way pipe junction' (I can lift the man hole and see this). and then onto a septic tank. One of the junctions in the "three way pipe' goes under the house, and as i discovered yesterday is blocked off. What i want to do is create another bathroom at the front of the house, utilising this blocked off pipe. I intend to run a waste pipe parallel to the blocked off pipe, turn it 90 degrees to meet it.
My questions are. Firstly is this something i need to get building inspectors involved with? Where the new pipe meets blocked off pipe do I need to build it into some sort of inspection enclosure with a manhole cover? The total length of the new bit of pipe about 6-7m, it will drop about 180mm along that length, is that enough drop. Finally, as well as taking toilet waste, the stack needs to be able take water from the new sink, what hardware do I need to to do this? (ie pipe for toilet waste and sink waste combined)

Hi Gidso,

firstly yes i think this is something you may well need to get building control involved with, best to give them a ring and have a chat!

Where your new pipe meets the old blocked off pipe you will need an inspection chamber as these are needed at junctions in case of blockages etc. As for the fall you suggest, by my calculations if you run a 7m pipe with a drop of 180mm then that should be just about the right fall as you need a minimum fall of 1 in 40!
You will obviously need the appropriate connections to join to the stack - have a read of Approved Document H as this will give you an idea of how to connect to the stack etc then its a question of going to your local builders merchants.

Hope this helps