EPA and/or PA DEP require municipal water systems to conduct periodic monitoring and reporting

Rules and regulations, however, have not been updated to reflect the influx of gas drilling and potential impacts on public drinking water supplies

Existing rules presume that conditions are unlikely to change rapidly.  If past tests show no contamination, then new contamination is less likely in the short term and the next required test may be years off.

Monitoring Requirements in the Pennsylvania Code - See Subchapter C

Here are some resources to check in on drinking water systems

PA DEP Drinking Water Reporting System (DWRS)

The DWRS allows public access to public drinking water systems' sample history, inventory information and recent violation history

Privately operated systems in Pennsylvania:

PA American Water

Aqua America

United Water

Nationwide Database:

Environmental Working Group