Vacuum breaker (anti-siphon)

A vacuum breaker (or anti-siphon valve) is a simple backflow-prevention device that admits air into the pipe the moment supply pressure drops, instantly breaking any siphon that would otherwise suck used or contaminated water backwards toward the clean supply. It's the specific, everyday form of backflow protection you find on the fittings most likely to create a cross-connection: garden hose bibs, irrigation lines, and appliance fills — anywhere a hose could sit submerged in a bucket, a pool or a planter. If the mains pressure suddenly falls (a burst, or heavy demand nearby) and there's no vacuum breaker, that dirty water can be drawn back into the pipework; the vacuum breaker simply lets air in first, so nothing siphons. In a Dubai home — where most properties feed from a stored tank — that protection is what stops irrigation or hose water reaching the drinking supply, so keeping a clean stored supply (periodic tank cleaning) and proper anti-siphon fittings work together. They're cheap, often built into outdoor taps and irrigation valves, and easy to add — a standard part of a safe install by Al Ghubaiba's water-supply team. It sits alongside the stopcock and gate valve on the supply side.