Hello, thanks for all the info. I live in the uk and I’m trying to design a system on a slope of about 12%. I cannot find double ell anywhere online. In your book you mention using a wye or tee instead. The tee looks like a severe bend for the flow. If i were to use the 45degree wye i thought i could keep the flow constantly going downhill. Have you any idea what the spilt of water might be? I can keep the kitchen sink, shower, washing machine all separate. Thanks again, Loretta