If you have the room you can even plumb in several water heater tanks into your water system. Many tanks are replaced simply because the electricals went bad or someone switched from gas to electric. They are glass or porcelain lined so unless they were handled roughly and the liner cracked rustout is not usually a problem. You can pick them up for scrap prices or free. Automatic water rotation, the fresh water comes in as the old water goes out when you open a tap. Flush any sediment out and slosh some bleach in there before you hook it up. Added bonus in the summertime is the water sits in the tanks and heats up from the ambient air temp, so less energy is used by the actual water heater.
I just use the Coghlans (sp?) water purifier tablets sold at almost any sporting goods department in the camping aisle. The tablets are all basically the same stuff, the one I bought last time has a bottle of vitamin c tablets to add after the purification process is complete. Supposed to remove a lot of the taste. I can tell a little difference, but not much.
There is another type out there, not really a tablet but iodine crystals in a bottle. You add water, which dissolves some of the crystals and makes a concentrated iodine liquid. Based on a temp chart and bottle size you then add a measured amount of the liquid to your water. Never tried it but some people like it as one bottle seems to last for years.