[ok cleaning]

wheres the best place to get a black water tank ? 

[oldman]

Depends on where your from and whether you can collect or want it delivered, as delivery (at £45-£55 +) can sometimes out-weigh the savings.

You could spray the normal ones black or even wrap the tank in a DPC Membrane.

This company steam cleans all their tanks and barrels........

http://www.toucanenvironmental.co.uk/1000-litre-black-ibc.html