Unpleasant Water

The majority of complaints from the municipal water supply involve discoloured (yellow) or smelly water.

Yellow water in York Region is generally a result of high iron concentrations found in the groundwater sources. The natural levels of iron concentrations vary throughout the Region's groundwater based municipal supplies and are generally above the aesthetic objective set by the Ministry of Environment.

York Region uses a treatment method known as iron sequestration to keep iron in suspension in the water to reduce the tendency for iron to "fall" out of solution and deposit and accumulate on fixtures. The iron sequestration process involves adding a chemical called sodium silicate to the groundwater treatment process.

The majority of yellow water complaints are hot water related. When the treated water is heated in a hot water tank, the iron sequestration process breaks down, allowing the iron to fall out of solution and build up in the bottom of the tank. This is noticed more frequently in tanks with high water temperatures and relatively low water usage (many people notice a problem after their children leave home and the amount of water use is reduced). Draining and flushing the hot water tank regularly may keep iron deposits from accumulating. 

There are times when consumers complain that their tap water smells 'bad'. Sometimes smelly water can just be a result of water sitting in household pipes for an extended length of time. This can usually be corrected by turning on some taps for a few minutes allowing fresh water into the household plumbing system and flushing any built-up organic matter (like hair, soap, and food waste) which may have accumulated in drains. If a smell is noticed from the hot water supply, the hot water tank may require draining and flushing.

There are, however, certain times during the year when people might find a musty or earthy like taste and odour in their tap water. These complaints generally come from those communities serviced by surface water treatment plants. The odour events tend to occur during the late summer and/or early fall. The communities most affected in York Region are Keswick, Sutton, Vaughan, Richmond Hill and Markham.

Earthy odours/tastes typically result from the growth of certain types of algae in the lake. When the algae begins to die off in the fall, it releases a harmless organic chemical, which creates a musty or earthy taste and odour. The filters at the water treatment plants are equipped to eliminate taste and odour problems associated with the water at normal levels of algae growth. There are years, however, when algae growth is extreme and filters are unable to control the incoming taste and odour problems.

This problem is generally seasonal, lasting from August to November and goes away during the cold water season. Despite the musty taste and odour, the water continues to be safe to drink.

Home Treatment Devices

Many people use point-of-use treatment devices to filter their tap water prior to consumption. The intent of these systems is typically to remove some of the odours associated with disinfection that is used by York Region to ensure that the water is safe to drink when it reaches the consumer. Improper usage or maintenance of a home treatment device can result in drinking water with harmful chemical or bacteria levels.

The treated water supply in York Region is tested continually, both at the source and throughout the distribution network, for the presence of harmful bacteria and tested regularly for several hundred chemicals. It consistently meets and surpasses all federal guidelines and provincial standards for drinking water quality.

Click here to find more detailed Water Quality information for your community.