bisphenolA cannot be present in HDPE or PP plastic tanks. Those are polyolefins that are translucent white - same as milk jugs.
BPa has sometimes been added to clear polycarbonate (PC) articles (Nalgene bottles) but in very low (ppb) levels. Nalgene and most other PC container manufacturers no longer add BPa to their products.
PET (polyethylene terephthalate) bottles (all carbonated soft drink bottles and water bottles) also cannot contain BPa, although it is commonly believed that they do...
The risk associated with BPa is infinitesimally small. Remember that when you drink water from a glass, you also are drinking hundreds of thousands of glass molecules.
On many sailboats, water tanks are formed from FRP, which can contain tiny but significant concentrations of chemicals from the fiberglass resin.
Best Regards,
e
.::.