An alternative to chlorine pools, the BioTop Natural Pools use plants to keep water clean and clear. Wikipedia has some more info on natural swimming pools as well. These could make a great addition to a permaculture design site.
Shipping Container Pools are above ground pools built from shipping containers with a fiberglass pool insert. Each pool is pre-assembled with the plumbing under the decking and with the chid safety door and stairs, you would not need any fencing.