What is the healthiest option when choosing a rainwater tank?

Asked by Justine
Schenectady, NY

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.


Lee Hall

Answered by Lee Hall

Allen, TX

Sustainable Structures of Texas

August 30, 2010

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.

  1. Cost. These things come in fairly large sizes and require no underground installation.
  2. 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.
  3. 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.

For more information:

Read Polly Osborne's Q&A "I would like to use graywater for my 150-year-old brownstone in New Jersey. Is it feasible to use the old cistern?"

Tagged In: water saving

Do you have a question about greening your home? GreenHomeGuide invites you to Ask A Pro. Let our network of experienced green building professionals – architects, designers, contractors, electricians, energy experts, landscapers, tile & stone specialists, and more – help you find the right solution.