Backflow is the undesirable reversal of flow of non-potable water or other substances through a cross connection and into the piping of a public water or a consumer's potable water system. There are two types of backflow: backpressure backflow and backsiphonage backflow.
| What can cause backflow? |
| Backflow can be caused by a sudden drop in the water pressure in a public watermain, which can create a sub-atmospheric condition.
For example, if a drop in pressure occurs while a garden hose is in a bucket of dirty water, that water could backflow into the public water system, potentially contaminating the water for other users. A drop in pressure could be caused by a variety of things, including a watermain break or a loss of power at a pump station. |
| Backflow Prevention |
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When water is accidentally mixed with hazardous chemicals, it can be extremely dangerous. When any hose is connected to a harmful substance while pressure in a watermain drops, the water and the contaminants could be sucked back into your pipes and water drinking supply. Water pressure drops are not uncommon. Watch for: Chemicals used as weed killer, insect repellant or lawn fertilizers, cleaners used on your kitchen sink, and even bacteria from your wading pool or waterbed. |
| To prevent contamination, the following should be practiced: |
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| What is a cross connection? |
| A cross connection is any temporary or permanent connection between the public water system and any source or system containing non-potable water or other substances. |
| Where can I get more information about cross connection control? |
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Visit the Ontario Water Works Association (OWWA) for more information at https://owwa.ca/backflow-prevention-in-ontario.html
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