According to the EPA, water violations are sorted into three high level categories:

• Health-based: Includes violations regarding maximum contaminant or disinfectant levels in water
• Monitoring and reporting: Includes failures to conduct regular monitoring or reporting of drinking water quality
• Other violations: Includes failure to to issue consumer confidence reports, or conducting periodic sanitary surveys

Note that violations are assigned to the public water systems (PWSs) within each state, of which there are often thousands. For example, Texas has 7,293 PWSs.

A PWS is defined as a system for the provision to the public of water for human consumption through pipes or other constructed conveyances.