thanks nige f, there is a man hole at each end of the run, the fall was set using laser level so i think it is pretty good for accuracy. the guys doing the work seemed very concentious. the pipes are set in the trench with shingle before back filling.
sorry people for a rather simple question, but i have just had some drainage fitted to a restoration job and the ground work guys have run the wc waste pipes at 80 to 1 slope from the house to the sewage treatment plant. This sounds like not much slope to me. THey say its ok if using 3m...