Just like with weather alerts, where the terminology of Advisory, Watch, and Warning can be confusing, there are different types and terminology used for water quality alerts. To better understand water alerts, here are three basic categories:
1. Emergency boil water advisory. These types of water quality alerts are issued when there is a confirmed detection of E. coli or some other pathogenic micro-organism in the water that can harm human health. These alerts should be issued immediately, and acted upon immediately by the public, to ensure illness does not occur. Emergency advisories account for approximately 22% of yearly alerts.
2. Precautionary boil water advisory. These types of water quality alerts are issued when there is the potential for water quality to harm human health, but any actual danger has not been confirmed. For instance, when there is an equipment malfunction or breakdown in the water supply system. Typically, testing of the water will be taking place to check that it is safe, and in the meantime, following the directions of the advisory is a good precautionary measure. Precautionary advisories account for approximately 75% of yearly alerts.
3. Do not consume or do not use advisory. These types of water quality alerts are issued when there is something affecting the water supply that cannot be resolved by boiling the water. A do not consume alert might happen because there is a high concentration of a non-volatile chemical in the water, such as a metal compound, that could make you sick by drinking or cooking with it. But you can still use the water for showers, etc. A do not use alert might happen because there is a high concentration of a volatile chemical in the water, such as chlorine, that could cause health effects through external use, such as taking a shower or breathing in fumes from the water itself. Both of these types of alerts should be acted upon immediately by the public. These account for approximately 3% of yearly alerts.