Frequently, backflow is the result of uncontrollable forces. As someone who drinks water in the City of Chicago, it is important to be aware of cross-connection hazards and how to prevent them. Cross-connections can occur when there is a connection between the potable (drinking) water system and a non-potable water source. This can happen when you submerge a hose in soapy water buckets, pet watering containers, pools, tubs, sinks, drains or any other container of liquid that does or could have contained chemicals. If a drop in water pressure occurs, the contents that the end of the hose is in will be sucked up into the City’s water supply.