WATER

Question 1

Name three major elements of the multi-barrier approach to safe drinking water

Answer 1

*Source water protection: prevent contaminants from reaching lakes, rivers, groundwater, aquifers
*Drinking water treatment: processes, techniques and systems to clean water before it is distributed
*Drinking water distribution
system.

Question 2

What are the procedures and tools (multi-barriers and safeguards) to protect the three elements of the multi-barrier approach to safe drinking water

Answer 2

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

Question 3

Name the steps of a typical drinking water treatment

Answer 3

1. Screening: remove debris
2. Pre-chlorination:arrests biological growth
3. Coagulation: chemicals mixed with water to bind particles together creating micro flocs
4. Flocculation: gentle mixing increases the particle size to create larger suspended particles (flocs)
5. Sedimentation: flocs settle out
6. Filtration: capture solid particles. Effective against protozoa and cysts
7. Disinfection:inactivation of pathogens not physically removed by filtration

Question 4

Name three methods of disinfection of drinking water

Answer 4

1. Chlorination
2. Ozone
3. UV Radiation

Question 5

Name three by-poducts of chlorination

Answer 5

1. Chloroform
2. Trihalomethanes
3. Chlorate
4. Bromodichloromethane
5. Haloacetic acids

Question 6

Pros and cons of chlorination

Answer 6

PROS:
-Residuals are easy to monitor
-Cheap
-Used as a secondary disinfectant

CONS:
-Taste/odour of water
-Disinfection by-products
-Is not effective against criptococcus and giardia

Question 7

Pros and cons of ozone

Answer 7

PROS:
-High disinfectant capacity
-Removes taste/odout
CONS:
-Expensive
-Requires secondary disinfection
-Energy intensive

Question 8

Pros and cons of UV Radiation

Answer 8

PROS:
-Simple
CONS:
-Requires pre-treatment filtration
-Requires secondary disinfection

Question 9

How to prevent contamination of the water distribution system

Answer 9

• Design layout to maintain sufficient pressure
• Watermain maintenance and replacement
• Secondary disinfection
• Cross-connection controls such as backflow prevention devices
• Horizontal separation between a water main and storm sewer to avoid contamination.
• Portable water storage
• Disinfection of mains and reservoirs

Question 10

What are the next steps if a water parameter is abnormal

Answer 10

• Verify information is accurate: system operator, testing laboratory
• Notify relevant authorities: Ministry of Health, Ministry of Environment
• Re-sample: if appropriate
• Gather other data: turbidity, chlorine residuals
• Corrective action: increase disinfection, flush lines, equipment repair, identify cause
• Issue notice to public: DWA
  • Immediate: E. coli or fecal coliforms
  • Urgent: low chlorine residuals

Question 11

What should be included in a water advisory?

Answer 11

• What is the situation: Describe situation, including contaminants of concern and levels
• What are the health effects?
• When it occurred
• When they expect to resolve the situation
• Who is at risk?
• What can the population do to protect themselves? (including specific guidance on how to boil water and whether alternate water supplies should be used)
• What operator is doing to correct the situation
• Encourage recipients to share notice

Question 12

When should a BWA be issued

Answer 12

BWA - Generally issued when:
- Microbiological contamination
- Chemical: No detectable disinfection residuals
- Physical: Poor turbidity deterioration of source water quality
- Change in routine monitoring parameter
- Local maintenance on distribution system
- Minor equipment malfunction
- Breach in system (e.g. broken water main)