SWIMMING POOLS ARE A PROBLEMATIC REALITY of modern housing. In some regions, a house without a pool will be a tough sell. But conventional pools have many environmental down sides. They require chemicals such as chlorine, which are toxic in their production, and if they're not rainwater fed, huge amounts of treated water from the local utility. Heating and lighting them, of course, also add environmental costs, although there are ways to reduce outdoor lighting costs and use geothermal systems heat pool water.
Perhaps the best option of all is to give up the chlorine-based pool for "natural" swimming pools that use rainwater to refill, require no chemicals, and have a much lighter environmental footprint.
The video on this page shows one in use.