A cross-connection is a point in plumbing systems where drinking water might come in contact with and be contaminated by hazardous materials: solid, liquid, or gas.

For instance, a hose placed in a bucket with non-potable water (such as soapy water, pool water, etc.) could contaminate drinking water if the pressure at the site of the hose is higher than the water pressure in the home's plumbing. Precautions should be taken to ensure that low water pressure in the home does not allow back-siphonage by suction of contaminated water into potable water lines.

Here are some plumbing tips to help you avoid backflow incidents:

• Install backflow prevention devices on threaded faucets in your home, especially outdoor hose faucets. Inexpensive "backflow preventors" like hose connection vacuum breakers can be found at many local plumbing supply stores.
  
  
• Keep the ends of hoses clear of any possible contaminants. Never leave a hose in a sink, bucket, drain, or tub. Maintain an air gap between water levels in sinks, buckets, drains, tubs and plumbing devices such as faucets and inlet valves.
  
  
• Do not use a chemical application spray attachment on a hose without a backflow prevention device.