At sebring in 2005 someone rigged up a shower thus:
Take a mains water feed and split it in two. Run one to your shower rig for your cold feed. Connect the other to a long coil of Copper Pipe. Dig a hole in the ground, place copper pipe into hole and fill with charcoal and set light to it. Once well lit, fill the rest of the hole with earth to keep the charcoal burning more slowly due to lack of oxygen. Run the other end of the copper pipe to another hose to your shower head for your hot feed.
Connect both to a mixer unit and you have a mains fed hot and cold shower system!
Fair bit of hassle, but it worked well!