That begs the question on how can anyone "maintain" the waters system on a normal production boat. The first issue the tanks are all vented. The second issue is many of the tanks are generic fiberglass built in uninspected yards. Very few boat systems are built with food service grade plastics. Most of us fill our tanks from a deck opening using a dock garden hose. The water is stored in warm temperatures for extended periods of time in a vented tank made and piped with suspect materials. If you were a resturant the board of health would shut you down for serving liquids stored like that. If I filled a bucket with water and left it in my basement or garage for a week? Would you want me to serve your family water out of that bucket? Unless you are playing amatuer chemist with chemicals and test kits. The fill and vent will always be your achilles heel.