How can back siphonage be prevented in a water system?

Back siphonage is a condition that permits contaminated water to flow back into a clean water supply due to a drop in pressure in the system. This can occur during events like a water main break or when there's a high demand for water that leads to low pressure in the distribution lines.

Using a vacuum breaker is effective in preventing back siphonage because it is specifically designed to keep the pressure within a system from becoming negative. When installed at critical points, a vacuum breaker allows air to enter the system if there is a drop in water pressure, which breaks any potential siphon effect. It essentially prevents an unwanted backflow of water, thus protecting the potable water supply from contamination.

While check valves can prevent backflow, they do not specifically address the issue of back siphonage under conditions of negative pressure. Flow meters and pressure relief valves serve other functions in a water distribution system and do not specifically mitigate the risk of back siphonage. Flow meters measure the volume of water and pressure relief valves are designed to release excess pressure, but neither directly prevents the formation of a siphon that could pull contaminants back into the clean water supply.