Backflow vs Back-Siphonage in Sydney: What’s the Real Difference
The huge amount of water being used causes a drop in pressure within the street water main, causing a syphon. Because your hose is in the bucket (a cross-connection), the soapy contaminated water would be drawn up through the hose into your home and possibly into the street main. When the pressure is re-established, the neighbours could turn on their kitchen faucets and drink the chemicals from your bucket.
