Maintaining Water Quality
The Multiple Barrier Approach
With an increase in awareness of water quality across the country, it is the stewardship responsibility of Halifax Water to inform customers of the steps taken to protect their drinking water. To maintain high quality water standards within the Halifax Regional Municipality (HRM), Halifax Water utilizes a multiple barrier approach. The multiple barrier approach is a series of checks and balances from the watershed to the tap of the customer. It is considered, in the water utility profession, to be the most effective way to ensure public health protection.
Source Protection
Halifax Water has two major water supply sources for the urban area of HRM. Pockwock Lake, west of Halifax, is the source of supply for the Western portion of HRM providing water for the communities of Halifax, Bedford, Sackville and surrounding areas. Lake Major, near Cherry Brook, is the source of supply for the Eastern portion of HRM providing water for the communities of Dartmouth, Cole Harbour, Eastern Passage and surrounding areas.
The watershed around these lakes has been designated as a protected area under the Nova Scotia Environment Act. Activities on the watershed are restricted and closely monitored by a Watershed Manager and administered by a Management group consisting of representatives from Halifax Water, Nova Scotia Environment and Labour, Dept. of Natural Resources and the local community. Under the concept of "quality in, means quality out", a protected watershed ensures that surface runoff and inflow to the source lakes occur within a pristine environment.
Optimization of Treatment Process
 Halifax Water operates two large state-of-the-art water filtration treatment plants and seven small plants. The J. Douglas Kline Plant at Pockwock was commissioned in 1977, and the Lake Major Plant in Dartmouth was commissioned in 1999. These plants remove iron and manganese from the source water, inactivate and remove bacteria, viruses and protozoa along with the removal of other organics to improve colour, taste and odour. The basic treatment process is colour precipitation, which includes clarification, filtration, disinfection and corrosion control.
Through the utilization of programmable logic controllers and Supervisory Control and Data Acquisition (SCADA) instrumentation, the plant operators monitor and adjust the treatment process to ensure that the output is of the highest possible quality. The staff of the water supply plants are all certified operators in conformance with the Nova Scotia Environment and Labour Certification Program. Water produced by the plants meets or exceeds the "Guidelines for Canadian Drinking Water Quality", as established by Health Canada.
Sound Distribution System Management
 Halifax Water has a proactive water main renewal and rehabilitation program to ensure the long term integrity of the distribution system. The annual capital program provides for the replacement of approximately 2500 m of structurally deficient and/or undersized pipe every year to improve the distribution system. This program helps reduce water wastage due to leakage and improves flow capacity and water quality. Halifax Water also has a proactive rehabilitation program for older cast iron pipes that have reduced capacity due to internal tuberculation. Instead of replacing pipes at higher capital costs, pipes are cleaned and lined in place which improves water quality, increases service pressure and improves flow capacity in the distribution system. Costs for cleaning and lining water mains are approximately one third of replacement costs. On an annual basis, approximately 5 km of water main are rehabilitated.
In addition to the installation of an internal cement or epoxy lining, the pipe exterior is protected from corrosion by the installation of sacrificial anodes. The anodes corrode instead of the pipe, thereby extending its life.
Cross Connection Control
Halifax Water has an active Cross Connection Control Program which minimizes the risk of contaminants entering the distribution system from the customers' premises through backflow. Backflow can occur if water is siphoned from a customers' premises due to a reduction in pressure in the distribution system or as a result of pressurized equipment being used on the customer's premise.
Our Cross Connection program began in 1990 with Backflow Prevention (BFP) devices installed on all new commercial and industrial services. In addition, Halifax Water instituted a retrofit program with BFP devices installed on existing service lines to high risk facilities such as hospitals, port facilities, mortuaries, laboratories, etc. All BFP devices are tested on an annual basis to ensure that the devices are operating to approved standards.
Continuous Monitoring and Testing
 Halifax Water tests all water tributaries flowing into both Pockwock Lake and Lake Major, and operates a laboratory at each of the water supply plants to ensure that continuous sampling and testing is carried out as an integral part of the treatment process. The distribution systems supplied from Pockwock and Lake Major are tested twice per week from samples collected at approximately 48 designated stations for quality and bacteriological safety. In addition, the seven satellite systems operated by Halifax Water, outside the urban core, are tested on a weekly basis. Tests are carried out by an independent certified laboratory with results sent directly to NS Environment and Labour who monitor the performance of Halifax Water. Halifax Water staff are committed to supplying drinking water in compliance with the highest standard in the land, the "Guidelines for Canadian Drinking Water Quality", as established by Health Canada. In addition, in 1996 a water quality committee was established with representatives from NS Environment and Labour, Halifax Water and the Medical Health Officer to address water quality issues in a proactive manner and establish protocol for emergency response.
It is through all aspects of this multiple barrier approach that Halifax Water staff can confidently ensure that water quality standards are maintained to the highest level for the benefit of the residents of HRM.
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