How to Find Communities in Need?

Hi,

I run a nonprofit that helps communities in Latin America gain access to clean water and proper sanitation, and I was wondering if anyone could give some advice on how to find communities in need? Do I contact the local government? Local community groups/organizations (how would I find these)?

I found our first project very randomly by contacting someone who was an author of a report on clean water, and they put me in contact with someone, who put me in contact with someone else. I figure there's got to be another way to do it, and so I thought I'd as what others have done in the past. 

Thanks!