can I use my old spring water cistern for heat storage?

[penfrydd]

Have maybe a 600 gallon cistern in basement that was used for spring water when I first moved here. Any reason I can't use that for thermal storage? Insulate with some sort of foam and then some sort of liner...Anyone know what sort of liner material I should be looking for? It would be about 30 ft from the boiler and at a slightly lower elevation.

Thanks