Q: What is the healthiest option when choosing a rainwater tank? I am most concerned with the quality of the water as it comes from the tank and am worried about the materials/chemicals that the tank is made of.
Sent by Justine
Editor: Here's what our friends at Green Home Guide have to say.
Answered by Answered by Lee Hall, Sustainable Structures of Texas:
Choices of materials for storage of harvested rainwater are:
- an in-ground cistern in natural rock,
- an in-ground, concrete-encased cistern,
- a rubber bladder,
- plastic drum,
- galvanized metal.
If you have the natural rock option available and none of these materials sound great, you could have a geotechnical testing firm test your rock to inform you of the leaching tendency of the rock. Then you would have to make your choice.
I like the rubber bladder option for a number of reasons.
- Cost. These things come in fairly large sizes and require no underground installation.
- Location options. The best would be under a deck, unless you are wanting to show all your friends your cistern. The under-deck option keeps the rubber cool, thus, in my mind, minimizing the leaching tendency of the rubber.
- The rubber bladder would probably be new. Therefore, any temptation to use "used" plastic or metal drums (who knows what has been in them) would not be a problem.