Treatment for Pathogens

Treatment is a key component in the multi-barrier approach to drinking water protection; and an integral part of the design and construction of a small water system. The primary objective of any small water system is the provision of clean, safe and reliable water to the water users, but the details of how safe water will be provided must be considered. When designing a small water system or, specifically, its treatment system, as a minimum, the designer needs to consider the following:

  • What is the chosen type of water source and is it appropriate for your needs?
  • Do you have a backup or alternate source, or considered getting one?
  • What is the source water quality and does it meet the Guidelines for Canadian Drinking Water Quality (GCDWQ)?
  • What is the population served (i.e. how many water users are served) and does it include high-risk populations such as schools, daycares, medical/dental facilities, adult care facilities, etc.?)
  • Does the water system include non-residential high-use water users such as commercial enterprises, industrial facilities or agricultural operations?
  • Is the proposed maximum treatment capacity adequate for the system and population served?
  • Are there any potential threats to the water system (from source to tap)?
  • Will the treatment system meet the appropriate BC drinking water treatment objectives?
  • Have the appropriate public health engineering standards been adhered to?
  • Will the proposed treatment system provide a clean, safe supply of water in sufficient quantity?
  • Have you considered other operational requirements such as backup power and service needs?
  • What treatment equipment will be employed (i.e. filters, ultraviolet lamps, chlorine contact chambers, reservoirs, pumps, etc.)?
  • Where will the sampling taps/ports (re monitoring) be placed?
  • Have you implemented measures to prevent fire and flood damage to your source, treatment system and distribution system?

As part of the multi-barrier approach to safe drinking water, treatment typically involves the use of two or more forms of treatment as no single type of treatment is effective in treating all waterborne pathogens (bacteria, viruses and protozoa). It is also vital to consider possible chemical contaminants (e.g. nitrates, arsenic, uranium, etc.).

As a starting point in the design of a treatment system, we recommend that you refer to the BC Ministry of Health’s Small Water System Guidebook, which provides descriptions of all the components of a small water system, from source to tap, as well as the regulatory requirements, treatment objectives and more.

Design Guidelines for Small Water Treatment Systems

The design and construction of a small water treatment system must comply with all local and provincial bylaws and regulations and conform to good engineering practices. There are several widely-adopted design and construction guidelines for BC waterworks, which include the following:

Design Guidelines for Rural Residential Community Water Systems

The Master Municipal Construction Documents (MMCD) Standard Specifications and Drawings 

Guidelines for the Construction of Waterworks by Interior Health 

With the assistance of the regional health authority’s Drinking Water Officer (DWO) and Public Health Engineer (PHE), you will also need to select the appropriate treatment to meet the minimum pathogen log reduction requirements for your water source. To learn more about drinking water treatment, refer to Resources for Designing Treatment for Small Water Systems.

Certification Requirements for the Systems Parts

When purchasing commercial materials, products and chemicals to build or use in a drinking water system, you will need to ensure that the products are certified for use in a drinking water system.

NSF Certified Products

The BC regional health authorities require NSF certified products be used when new water systems are constructed or existing systems are upgraded.

You do this by looking for information, such as a trademark, that says the product meets the required NSF Standard, indicated by the NSF symbol. “NSF” stands for National Sanitation Foundation which is an internationally recognized organization that provides accreditation for a variety of consumer products including drinking water treatment equipment. Emerging technologies or equipment with NSF certification indicates that the product and its materials have been reviewed and certified by NSF to meet the NSF safety and performance standards claimed by the particular manufacturer or business enterprise. In drinking water systems, the NSF certification provides credibility and industry acceptance.

The BC regional health authorities require NSF certified products be used when new water systems are constructed or existing systems are upgraded.