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System Score Pages:  Search

On this page:

• About System Scores
• Priority Non-Compliers (PNCs)
• How System Scores Are Calculated
• Violation Severity Factors (Points)
• Service Area Types

A system score is a point-based value that provides a comprehensive approach for assessing a water system's level of compliance. A single value is calculated for each water system based on compliance with all rules, instead of using the rule-based SNC (significant non-compliance) status which was based on failure to comply with individual drinking water rules. System scores are used to identify systems that are a high priority for enforcement (see Priority Non-Compliers, below).


When a water system's system score reaches 11 or higher, the system is considered to be a priority non-complier (PNC). The system remains a PNC until its system score falls below 11 and all MCL violations have been addressed.


The system score is based on all unaddressed violations (those that have not been returned to compliance and are not under formal enforcement) for monitoring periods ending within the last five years. Violations for monitoring periods ending more than five years ago and those that have been addressed are not counted in the system score. Each violation type is assigned a point value indicating its relative threat to public health, or severity (see the points table, below). The system score is calculated by adding together the points of the unaddressed violations and adding a time factor; the time factor is the number of years that the oldest violation has been unaddressed (from 0 to 5 years). For each water system, a system score is calculated using this formula:

          System Score = Sum (S₁, S₂, S₃, ...) + n

where S represents the points for each violation and n represents the time factor. Water systems with a system score of 11 and higher are considered a higher priority for enforcement.

Notes:

• The time factor (n) is calculated as the number of months between the violation's monitoring period end date and the current date divided by 12 months/year. The resulting number of years is rounded down to the nearest whole year.
  
• System scores on Data Online are based on the 5-year period from today's date and reflect all data currently in the Drinking Water Services' database.
  
• View current system scores here.

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