"Bruce on horizon" writes:

Is it possible to build a fuel tank (diesel) that will not deteroiate from
the fuel. Also water...is there a problem with fiberglass water tanks?

SFWIW.

I have built all my tanks, diesel, potable water and hydraulic oil the same
way.

Epoxy and knitted glass followed by two (2) coats of epoxy tank resin. (A
white coat followed by a blue coat).

Waste tank was done the same way, only coal tar based tank resin was used to
coat the interior.

YMMV.

Lew