Vancouver Coastal Health (VCH) has informed the SLRD of a new direction that requires the SLRD to provide a Water Quality Advisory for residents of Pinecrest Estates.
Drinking water systems that rely on surface water sources, such as the Pinecrest Estates water system, are at risk of containing pathogens that can cause illness if left untreated. While the majority of these pathogens, such as bacteria and viruses, can be effectively controlled through chlorine disinfection, some protozoan parasites, such as Cryptosporidium and Giardia, are resistant to chlorine. For this reason, surface water supplies in British Columbia require a secondary disinfection step, such as ultraviolet (UV) treatment.
Currently, the existing UV treatment system at Pinecrest Estates is intermittently alerting operators to low UV transmissivity (UVT) in the source water. While the Squamish Lillooet Regional District (SLRD) investigates and implements a solution to remedy this issue, a Water Quality Advisory is being issued for your home.
Why is there a Water Quality Advisory for Pinecrest Estates?
Pinecrest Estates residents' water is supplied from Retta Lake, which is a surface water source. In accordance with the province’s Drinking Water Treatment Objectives for Surface Supplies in BC, water is treated with two forms of disinfection: chlorine and Ultraviolet (UV) treatment.
The effectiveness of ultraviolet (UV) technology for treating drinking water depends on several key factors related to the quality of the incoming source water. One critical factor is UV transmissivity (UVT), which is the ability for the UV light to pass through water and inactivate pathogens.
Recently, the source water quality from Retta Lake has frequently fallen below the minimum UVT threshold required for the UV reactors to operate effectively. During these periods, the water still receives some UV exposure in addition to its regular dose of chlorine. However, there remains a small risk that some parasites, such as Giardia and Cryptosporidium, which are not detected by routine bacteriological testing, may survive the disinfection process when UVT is low. Under these conditions, the UV treatment may not fully inactivate these target parasites.
Routine monitoring for indicator bacteria, including total coliforms and E. coli, is conducted every two weeks and consistently shows no presence of these organisms.
Q&A
Understanding that the language in the water quality advisory above is quite technical, please find answers to some of the more common questions about water quality advisories below.
For more information, view HealthLinkBC's Preventing water-borne infections for people with weakened immune systems.
If you have questions, you can contact the SLRD directly by email at utilities@slrd.bc.ca. Alternatively, contact your local Drinking Water Officer at angela.whalen@vch.ca.