Fact Sheet
Improving Water Quality On-Reserve
Assessing Risk on Drinking Water Systems

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“Risk” pertains to the vulnerability of the system and the potential to produce unsafe water.

Five main criteria are used to assess risk:

• Source water quality
  
• Infrastructure/design adequacy
  
• Operation and maintenance of system
  
• Operator training and certification
  
• Record keeping and reporting

The risk level for each area is then weighed to determine the overall risk level of the system.

A system classified as low risk is generally working relatively well in all of the areas. It may have minor deficiencies in a couple of areas which can be easily addressed or corrected through the course of normal operation and maintenance of the system. Should something fail or should a problem occur in one of the areas, because the other areas are all working well, they should compensate for that failure and keep the water safe until the problem is corrected. The chance of having unsafe drinking water when a problem is encountered is therefore very low.

A system classified as medium risk will usually be significantly deficient in one or two of the above areas, or have minor deficiencies in all five areas. If one of the deficient areas were to fail, the other areas could likely compensate for the problem: if however, there are deficiencies in other areas, the likelihood other areas could compensate is reduced, thus the risk of a problem resulting in unsafe drinking water is increased from low to medium.

Finally, a system classified as high risk is usually significantly deficient in several - if not all five - of the areas. Should a problem occur in any part of the system, it is unlikely that the other areas would be able to compensate for that problem. A failure of any part of the system could therefore likely result in unsafe drinking water.

As of March 17, 2006, 193 systems were identified as high risk, 312 as medium risk and 250 as low risk.

March 21, 2006