Hazards to Your Source


After determining the source assessment area, you will then identify the hazards that could negatively impact your water source. A hazard is a condition, event, action or inaction that poses a threat to either human health or your sustainable supply of water. 

Biological contaminants include bacteria, viruses, protozoa, algae and parasites that could cause adverse health effects. 

Chemical contaminants include dissolved metals (e.g. manganese, copper, cadmium, lead, etc.), arsenic, antimony, fluoride, hydrocarbons, pesticides, total dissolved solids, endocrine disrupting chemicals and nutrients (e.g. phosphorus and nitrates). 

Physical contaminants include suspended sediment (turbidity). 

Radiological contaminants include cesium, plutonium and uranium.

You should assess for anything that has the potential to impact:


the quality and quantity of the water supply

the health of the water consumers 

the integrity of the water system infrastructure (including the well or surface water intake)

Drinking water hazards include contaminants (undesirable substances or matter that may cause harm) which include biological, chemical, physical or radiological contaminants.

Hazards to the source can include events that could damage infrastructure such as floods, landslides or wildfires. You can identify the source water hazards by walking the land, using your local knowledge of the area and reviewing historical information. When you are creating your hazard inventory, you need to consider the vulnerabilities of your source water and assess the risk of each hazard to determine which hazards are the most important, or highest priority. Map and record the identified hazards in a Hazard Inventory (you can use this source protection toolkit)

If you miss a significant hazard (high risk), it cannot be controlled or mitigated. However, applying preventive measures for a hazard that is not significant (low risk) is a waste of time and resources. Understanding the results of the risk assessment in the context of the water supply system as a whole will allow you to create an effective risk management strategy. After assessing the risk from potential hazards, you will be able to set priorities and develop mitigation strategies that will be incorporated into your source protection plan.