WASHINGTON (AP) — Scott Harrison knows his charity has funded nearly 7,000 clean water projects in some of the poorest areas of the world in the past six years. How many of those wells are still flowing with drinking water months or years later, though? That’s a tough question to answer.

His organization called Charity: Water has funded projects in 20 different countries. It’s committed to spend 100 percent of each donation in the field to help reach some of the 800 million people who don’t have clean water and resort to drinking from swamps, unhealthy ponds or polluted rivers. Organizers send donors photos and GPS coordinates for each water project they pay for.