River with rocks and trees

Principle 6: Apply a preventive risk management approach

Ivan Ottenheijm

May 10, 2022

Drinking Water Standards, The 6 Principles of Safe Drinking Water


You are going on a holiday and you’re unsure if it might rain? You bring your raincoat anyway. There is no phone reception where you’re going? You may let someone know when you should be back. Would you drive a car with no seat belts and airbags? Although you may not think you will need them, you do want these features - just in case. These are examples of how we apply preventive risk management in our daily lives. The same approach is expected of a water supplier.

Principle 6 of drinking-water safety in New Zealand tells us to apply a preventive risk management approach. This requires a systematic assessment of risks throughout a drinking-water supply from source to tap, identification of the ways these risks can be managed, and control measures implemented to ensure that management is occurring properly.

Preventive risk management doesn’t mean we can prevent any possible outcome, but it does mean that we think of risks that can reasonably be expected in a structured way and apply controls that are appropriate. We wouldn’t drive a tank in the streets to prevent getting injured during a crash, but we all agree seat belts and airbags are probably appropriate controls. This is a standard applied universally to passenger vehicles. When it comes to preventative risk management for water suppliers, there are currently a range of approaches. This is where we see an inconsistent approach across the country and a varying degree of risk tolerance.

There are water suppliers who are extremely risk averse and have a 7-log treatment process and two processes for bacteriological inactivation for a 3-log source. Further up the same river, another water supplier has a 3-log treatment process and one process for bacteriological inactivation. In other words, you could say there are no seatbelts and airbags and when something goes wrong, we go into damage control, a boil water notice and hope for the best.

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