Peter Hendra wrote:

A fellow boater here in Trinidad has rusty steel water tanks with a
couple of pin holes in them. He doesn't have a lot of money but does
have a supply of cold tar epoxy.

Question: Should he drink the water from the tanks if he paints them
internally with said cold tar epoxy? Are there any isocyanates or such
that will leach into the water that would be harmful to his health.

If so, what would be the most cost effective (cheapest) internal
coating?

Not a good idea to use coal tar epoxy on potable water tanks.

SFWIW, I used CTE on my holding tank.

There are resins specifically made for coating potable water tanks.

They are known as tank resins.

I'd use two (2) coats, white followed by some other color.

SFWIW, that's what I did based on the suggestion of the supplier.

Makes it easy to see if you missed anyplace.

Have fun.

Lew