Over the past several months we've covered a number of issues related to drinking water, including posts on concerns about the quality of U.S. drinking water, possible contaminants in drinking water, and states requiring deposits on bottled water.

Another organization that pays a lot of attention to drinking and bottled water is the Environmental Working Group. The latest effort from the EWG is the Bottled Water Label Scavenger Hunt, which the group touted in an e-mail it sent out earlier today.

In the letter, the EWG asks, "Ever look at a bottle of water and wonder, 'Where does the water come from? Is it purified? Did the FDA make sure it's safe and clean?' "

The e-mail goes on to say that to participate in the scavenger hunt, "The next time you buy a bottle of water . . . choose a non-sparkling, unflavored water bottled in glass or clear plastic." The EWG wants you to remove the entire label from the bottle since it needs all information for its project. Then send the label with the following information to the EWG (Environmental Working Group, Attn: Nneka Leiba, 1436 U Street NW, Suite 100, Washington, DC, 20009): the name of and the location of the store where you purchased the water; the date you bought the water; and your name and e-mail and regular-mail addresses.

According to the EWG, the person who submits the most unique labels by June 15 will win a stainless-steel water bottle and a reusable grocery bag; anyone who participates will get the EWG's Shopper's Guide to Pesticides magnet. e-mail | Twitter

Essential information: Learn how to decipher the report from your community water system.