What are the two general types of backflow in drinking water systems?

The two general types of backflow in drinking water systems are backpressure and backsiphonage.

Backpressure occurs when the pressure in the system downstream of a water supply exceeds the pressure in the supply line. This can happen due to various factors such as pumps pushing water into the system or thermal expansion. It creates a situation where contaminated water can flow back into the potable water supply.

On the other hand, backsiphonage occurs when there is a negative pressure in the water supply system, such as during a sudden drop in pressure due to a water main break or when water is drawn out rapidly, like in firefighting situations. This negative pressure can cause contaminated water from an adjacent source to be siphoned back into the drinking water system.

Recognizing these two types of backflow is crucial for water treatment operators, as they must implement appropriate measures to prevent contamination of the drinking water supply from either occurrence. Effective backflow prevention devices and strategies are essential to ensure that the drinking water remains safe and free from hazards.