WellOwner.org is a great resource if you are planning to drill a well or if you already have one. Be sure to download their free and comprehensive Well Owner's guide produced by National Groundwater Association.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

The EPA has many links to great educational materials and resources. Go to epa.gov/privatewells.