This is upstream a bit from the old DOC vistors' centre at the end of the Routeburn road. We rolled the tub off the terrace top and watched it bounce down across the river boulders. Yes, it’s seriously tough.

Water was bucketed in from the river: takes only a few minutes (you can shift water surprisingly quickly with a bucket or two).

Afterwards, just disconnecting the bottom hose drained the tub in two minutes. No chemicals, so it’s safe to put the warmed water back into the river: it mixes in almost immediately.