I was just asked about how to build a low-cost solar water heater. It's actually the subject for a planned how-to article but let me toss out two basic design ideas. If you are creative you should be able to construct either one. Solar water heaters used to be inexpensive but, today, they seem to have out of control prices. It just makes no sense why someone would be expected to spend $1000 or more when they are such simple devices. The two ideas I will present are a "box heater" and a "plastic pipe" heater.