Last Updated 2025/09/26
Hagensborg Water System FAQ by Meg Schadt
Knowing that the Hagensborg water system is full of organic matter and will continue to be for the foreseeable future, and knowing full well that when organic matter and chlorine come in contact with one another, they form various disinfection by-products that are harmful for human consumption, will the CCRD still choose to comply with the VCH and move forward with chlorinating the Hagensborg water system?
The potential to form disinfection by-products has been considered in both the design of the Hagensborg water system upgrades and the ongoing operation / monitoring of the system.
The health authority has confirmed that chlorination is a necessary step in the treatment process. Primary disinfection is needed to inactivate any viruses that may be present in the raw source water. Secondary disinfection is needed to protect against re-contamination of water in the distribution system by maintaining a low residual chlorine concentration in the pipes.
For the upgraded water system, the new groundwater wells will be the main water source. The existing Snootli Creek surface water intake will remain as an emergency backup supply. In terms of raw water characteristics, groundwater typically has lower organic content than surface water. This can vary seasonally or by each specific source, but water quality testing completed to date indicate that the raw groundwater at the Hagensborg well field is low in organics.
Part of the testing completed at the design stage is to assess disinfection by-product formation potential. This involves adding chlorine to a sample of raw water in a lab environment and then measuring any disinfection by-products that subsequently form. The testing completed for the Hagensborg wells revealed results below the Guidelines for Canadian Drinking Water Quality limits for disinfection by-products, specifically trihalomethanes.
We are working with Vancouver Coastal Health to develop the ongoing water testing program. This will include testing for the presence of disinfection by-products (trihalomethanes and haloacetic acids) in the system.
Prior to commissioning the new water system, the distribution system pipes will be flushed extensively to remove material that has built up in the pipes over the years. Most of the build up is understood to be sand / gravel material, but some organics could be present in the pipes from raw creek water being used to supply the system, specifically during high turbidity events. Activation of the chlorination system will be done slowly, using low amounts of chlorine and then slowly increasing the dosage based on real time testing. The intent is to dial in the disinfection settings so that the minimum amount of chlorine is being used. The UV system will be the main disinfection barrier being relied on.