It should be a little easier now to figure out which drinking water systems in your audience area have violated federal standards. EPA has updated its Enforcement and Compliance History Online (ECHO) database so that such violations through 2009 can be quickly identified.
- ECHO: Search Compliance Data  (Safe Drinking Water Program).
You can pick, say, a county and quickly get a listing of all systems, or ones of selected sizes or types of ownership, that fall into categories such as serial violators, or occasional violators of things such as health-based standards or monitoring requirements. Then you can contact the specific utility and cover the problems, based in part on the additional details in ECHO.
While you're looking at this data, it will also pay to check each local utility's annual Consumer Confidence Report, a mandatory document due each year by July 1. The CCR reports the concentrations of selected contaminants that have been identified in the water system in the past year (or the past few years for a few substances). This year's CCR will include violations in 2010 that aren't in the ECHO database. And even if there aren't any violations in 2010 or earlier, the latest CCR numbers can give you good insights on issues such as:
- whether a utility has high numbers of contaminants whose combined effects aren't accounted for in the standards
- whether some contaminants are occurring just below the standards EPA has set for them
- what the concentration is for a substance whose standard is being re-evaluated (for example, the enforceable standard for arsenic was lowered dramatically in 2006).
- Where You Live: Your Drinking Water Quality Reports Online  (provided online for larger utilities, or identifies the name, address, and phone for smaller systems so you can contact them).
- EPA offers further information on yet-unregulated contaminants that may be of concern here , here,  and here. 
June is also a good time to investigate how local utilities are handling typical seasonal threats to water quality, such as higher sediment concentrations in source water due to flooding, or elevated concentrations of contaminants associated with spring agricultural activities, such as pesticides, fertilizers, or bacteria in runoff from sources such as animal feedlots.