Check valves prevent backflow into sump disposal lines, wastewater lines, sewage lift stations, and ejector systems. Backflow preventers prevent contamination of potable water by keeping water from flowing backwards into a water supply line. Backwater valves protect against weather conditions that cause sewage overflow such as heavy rain. Foot valves are a type of check valve used in ponds and pools. Sanitary check valves prevent the backflow in sanitary and industrial applications. Vacuum breakers aid in backflow prevention to keep water from being siphoned backward into the public drinking water system.