Multi-Barrier Approaches

What Can Operators of a Water System do?

The Walkerton Tragedy was a wake up call for the city to realize the importance of water treatment, which is one aspect of ensuring the safety of water for the community. In order to prevent another waterborne catastrophy from reoccurring, it is crucial for the operators to have a comprehensive management plan and take appropriate steps in operating a water system. Posted here are some multi-barrier approaches that is essential for every operator and trained employees to have knowledge on.


Barrier Approach #1: Source Protection

A protected well head

Water serving to the public should be collected from safe sources. Whether the water comes from for instance, a shallow or deep aquifer, multiple wells, or a reservoir, the area supplying water must be protected from contamination and needs to be under close monitoring and testing. If the water source is contaminated, this also weakens the effectiveness of the disinfection action on water. In the case of retrieving water from wells, it is important to: 

• Maintain a proper set back distance and keep the well away from the nearest source of contamination
• Eliminate the source of contamination if it is present
  
• Provide a good well head sealing
• Conduct a detailed risk assessment plan of the area
• Have frequent water testing and ensure there is maintenacne procedures for the wells

 Barrier Approach #2: Water Treatment

In order to keep your water free of bacteria and other harmful germs, you must properly disinfect the water before it is delivered to the residents. A couple of strategies on water treatment include:

• Proper chlorination of your water: 

 a) Provide adequte concentration
               b) Conduct frequent chlorination
               c) Keep a record of the treatment activity

• Use combined water disinfection treatments such as ozonation or ultraviolet
• Always filter the water after the disinfection to remove chlorine-resistant parasites such as Giardia and Cryptosporidium which are infamous for causing gastrointertinal illnesses

Barrier Approach #3: Distribution System

A high quality distribution system provides continuous supply of potable water at adequate pressure. To protect the system from physical, biological, and chemical threats the operators should consider the followings:

scaling pipes

• Prevent aging, leaky, cracking, and corrosion on pipes. Also, beware of effect of installing pipes too close to the frost line that may freeze water from flowing
• Follow municipal standards for all materials used in constuction
• Consult with the engineers to develop an appropriate 3-dimensional design of a pressurized distribution system that will reduce the water's residence time in pipes
• Provide a storage reservoir when water demand fluctuates during different times of the day and during demands are high when there's an incident to distinquish a fire
• Prevent scaling of pipes
• Avoid slow water flow rate because sedimentation of particles in the distribution system may cause clogging or provides nutrients for the growth of bacteria
• Eliminate algae, iron, and sulphur since bacteria feed off those and biofilms may form over time
• Provide chemically stable water to reduce reactions that produce carcinogenic disinfection by-products

Acknowledgment: Justice Dennis O'Connor
Source:Source Protection