plastic holding tank ?

[mark]

would imagine you can get a food safe barrel for about the price of a plastic tub at Cdn Tire (these here were $35 for a 45g)

as for melting plastic, look up on youtube boiling water in a paper cup

[MMAX]

I'd suggest not using a tote, go for the Rubbermaid Brute instead. When you fill the tote with water the sides will deform and may blow out. I've used Brute garbage cans as rain barrels and have had zero issues with them.