Toilet waste pipe length?

[kedsy]

My upstairs toilet soil pipe is going through wall and into a downpipe then direct to sewer.

I want to move the toilet to the other side of the bathroom so would be bringing it around the sides of the room. So would be ina L shape, approx 2m by 2m.

What would be a reasonable length i could extend the pipework for the soil pipe? There is no play in the existing pipe either so i would be unable to alter the fall of the pipe.

 

[noseall]

by extending it another 4m you will need to find an extra 100mm of fall.

plus any 90deg bends will require acess covers.