What Causes Boil Water Notices in our Community?

The quality of water in Comox Lake is normally excellent, however, very high rainfall events cause runoff from the rivers and tributaries that feed the lake. This runoff can affect the turbidity, or cloudiness, of the water. Elevated turbidity levels can interfere with the chlorination of the water and increase the risk of bacteria entering the drinking water system, requiring a boil water notice to be issued.

Our New Water Treatment Plant Will Eliminate All Turbidity Related Boil Water Notices.

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The Comox Valley Watershed has experienced an increase in frequency and intensity of extreme rain events over the last decade. Major storms have pushed the reservoir to record high water levels twice since 2009.  Sediment from surrounding tributaries have increased turbidity levels in Comox Lake during these events. 

The photo below shows the Cruickshank River dumping turbid water into Comox Lake following a severe rain event, which resulted in a boil water notice. These events will not result in a boil water notice once the new treatment plant is in operation.

The surface water treatment objectives are applied consistently across BC – meaning the Comox Valley is being held to the same standards as all other communities. All other operators who exceed 1 NTU are put on boil water notices unless they have ultra-violet treatment and/or filtration. The turbidity limit of 1 NTU is consistent across Canada and all countries studied, except for Australia whose requirement is more stringent at 0.2 NTU.

To provide interim relief to turbidity-related boil water notices, the CVRD has installed UV reactors in the existing treatment plant, adding a second level of treatment and raising the allowable NTU. This additional level of treatment could eliminate up to 80 per cent of boil water notices – and the equipment can then be moved to the new facility when constructed.


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