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Residential Cross Connection FAQ
Did you know…
Did you know that one of the most likely ways to contaminate our drinking water is through a cross connection of the drinking water pipes that are connected to a source of contamination or pollution? Water normally flows in one direction. However, under certain conditions, water can actually flow backwards; this is known as Backflow. there are two situations that can cause water to flow backwards: Backsiphonage and Backpressure.
Backsiphonage could happen if there is a loss of pressure in the municipal water system due to a firefighting emergency, watermain break, or water system repair. This loss of pressure can create a siphon in your plumbing system, and if you had a hose in a wash tub, bucket, or pool, this could draw that back into your water or into the public water system.
Backpressure can occur when there is a source of pressure on the plumbing system that is greater than the water pressure from the public water system. A boiler or chemical tank that is pressurized with a pump can cause contamination when it creates pressure greater than the pressure supplied from the public water system and cause water to be pushed into your plumbing system and even into the public water system.
Cross connections can be found in commercial/industrial buildings, hospitals, school and residential homes.
How Do We Prevent Cross Connections?
Cross connections can be prevented either by a physical separation or by using a backflow preventer device.
A Physical separation means that there is an air gap between the source of the contamination and the pipe supplying drinking water. For example, if you were filling a pool and the hose was submerged in the pool, this would be a cross connection, by simply raising the hose above the rim of the pool would create an air gap where back siphonage could not happen.
A device called a backflow preventer could also be added to the plumbing system. This mechanical device, when properly installed and maintained, is designed to prevent contaminated water from entering the drinking water system. Not all backflow preventers are designed for every cross connection, there are several types of backflow preventers and knowing the situation will determine which backflow preventer is needed for that application.
Examples of Cross Connections
Residential Examples:
- Hoses submerged in buckets
- Lawn irrigation systems
- Water softeners
- Water assisted sump pumps
- Pools and hot tubs
- Boilers
- Well that is still in use
Industrial Examples:
- Lawn irrigation system
- Fire sprinkler systems
- Cooling towers
- Dishwashers
- Soap dispensers
- Hose connections
- Food processing equipment
- Laboratory equipment
- Mop/slop sinks
How is this Regulated?
All water utilities are required by Michigan Department of Environment, Great Lakes, and Energy (EGLE) to have a cross connection control program as explained in Part 14 of the Michigan Safe Drinking Water Act. The Cross Connection Rules Manual, which was published by EGLE, explains the cross connection control programs for water utilities. The Michigan Plumbing Code also has requirements regarding preventing cross connections.