What options are available to operate a simple 2 loop hydronic heating system when there is no domestic water supply available? I've come across a detached workshop with heating loops in the concrete slab but the shop is ~100ft from a house and the original installers failed to run domestic hot water to the shop. Obviously operating the closed loop hydronic system without a domestic feed is dangerous and running an underground supply line now would end up being quite costly. An insulated above ground supply line with heat trace is an option, but the climate is quite cold and I'd worry about possible failures.

I've heard of some guys using a polyethylene water tank and injection pump to supply water if needed. Has anyone had experienced a similar situation? What did the tank and pump system consist of?

What other options would be available?