West Marine Water Tank & System Flush able to freshen up freshwater tanks to eliminate nasty odours and tastes. It is ideal for commissioning after long storage or to eliminate pesky odours and taste that regular water treatments cant neutralise. This concentrated biodegradable formula is easy to use to treat tanks and the freshwater system. 3.79 Litres (1 gallon) will treat 378 Litres (100 gallons).