Think how good you have it with CAD programs, pumps and other electronic gizmos to design, control and monitor the flow of water. Imagine that these tools were not available to you. How would you like to try designing workable plumbing systems using only primitive materials and natural energy sources like sun, wind, currents and gravity? (The thought occurs that this might not be a bad exercise for an engineering class.)
This was precisely the challenge facing your ancient forebears. The archaeological record gives us an inkling of their ingenuity. Artifacts that have survived the onslaught of time tell of regal toilets and bathrooms, along with aqueducts and sewers to make life bearable for populations in advanced civilizations of antiquity.