From Source To Tap - The Multi-Barrier Approach To Safe Drinking Water

Introduction

Recent outbreaks of waterborne disease in Walkerton, Ontario, and North Battleford, Saskatchewan, have heightened Canadian awareness of the fact that threats to water quality and quantity can have a profound impact on their health, the environment, and the economy.

In recognition of the above, it is imperative that drinking water be kept clean, safe and reliable. In order to do so, the components of the water supply system - from source protection to the treatment and distribution of drinking water to consumers - must be understood and managed as a whole.

The multi-barrier approach is...

... an integrated system of procedures, processes and tools that collectively prevent or reduce the contamination of drinking water from source to tap in order to reduce risks to public health.

Even though no approach will guarantee 100 per cent protection all of the time, it has been demonstrated that the most effective way to manage drinking water systems is to implement a multi-barrier approach (see sidebar). The goal of this approach is to reduce the risk of contamination of the drinking water, and to increase the feasibility and effectiveness of remedial control or preventative options. As a safeguard, it is important for contingency plans to be in place to respond to incidents as they arise, and for redundancies to be built into the system wherever feasible.

Figure 1 (below) depicts a multi-barrier approach to safe drinking water that contains three major elements. These elements are source water protection, drinking water treatment, and the drinking water distribution system. These elements are addressed in an integrated manner by using a system of procedures and tools, such as:

• Water quality monitoring and management of water supplies from source to tap
• Legislative and policy frameworks
• Public involvement and awareness
• Guidelines, standards and objectives
• Research
• The development of science and technology solutions

Figure 1: The Multi-Barrier Approach

Enlarge image

Under the multi-barrier approach, all potential control barriers are identified along with their limitations. Limitations could include risks of pathogens or contaminants passing through the barrier. Individually, the barriers may be inadequate in removing or preventing contamination of drinking water, but together they offer greater assurance that the water will be fit to drink. This approach also helps ensure the long-term sustainability of water supply systems.

This document briefly discusses each element of the approach as a separate section, starting with the components in the outer ring of Figure 1 and moving towards the centre.