Affordable, Cub Scouts, DIY, Water Filter Experiment/Fundraiser Idea:

http://m.wikihow.com/Make-a-Water-Filter

Another few steps to add at the end would be to boil the filtered water for 15 minutes at a high boil, let it cool for thirty minutes, and add enough iodine/chlorine/chlorine dioxide, water purification tablets to further purify the water. You may need to keep a week's worth of tablets and safe, drinking water, in your home, in the attic.

The tablets should be in a triple layer of sealed, Ziploc freezer bags, then, placed in labeled, water-tight containers, with water-proofed/laminated, illustrated, child-friendly  instructions/directions, especially if you're living in a flood-prone area, e.g. Florida, or Louisiana.

Please ask the PTA Presidents, public, elementary schools' principals to acquire donations, to create a safe, drinking (emergency) water, plastic bin for all the ESL, impoverished/poor, latchkey, challenged children in your community.

They'll need to get enough bins for their entire families. Per one student on well-water, they need to be considered homeless, and issued enough bins for every single day of the entire year for themself, and all of their families.

A new, professional well, professionally-created, septic tank and septic field, a professional, well-water filtration system should be built for them, for free, on a half-acre of land, donated to them, with four, 2,000 square feet, emergency trailers, and a 1,000 square feet, all-metal, insulated, fire- and flood-proofed, chicken coop.

http://www.livestrong.com/article/169622-how-water-purification-tablets-work/#page=2