Many built in fiberglass tanks are made with polyester resin. Epoxy resin is a much better choice for several reasons--no blistering, less likely to leak. Most epoxy resins are not FDA certified--but there are a number of epoxy resins which are certified. Coating a fiberglass/polyester tank should help with the taste problem. 20 mils is a satisfactory coating amount. Google "Epoxy Potable water"--and there will be a number of approved epoxy coatings. Many paint companies have these in stock--such as Benjamin Moore and Sherman Williams. No West Systems Epoxy is in the approved group. However the tank may be made of any number of compatable epoxies, and then the inner tank coated with proper epoxies. Bob Austin