Cross Connection

Ways to Protect Your Home


  • Don’t submerge hoses in buckets, pools, tubs, ponds, etc.
  • Don’t connect piping from water softeners or other treatment units to a sewer connection or submerged drain pipe, etc.
  • Don’t use a hose to unplug blocked toilets, sewer pipes, etc.
  • Don’t leave garden hoses lying on the ground, especially if there is no spray nozzle attached.


  • Do keep the ends of hoses clear of all potential contaminants.
  • Do install hose bib vacuum breakers on all threaded faucets around your home. These devices are inexpensive and generally available at hardware stores.
  • Do evaluate backflow prevention device installations for the need of freeze protection.
  • Do install thermal expansion protection on containment systems, if necessary.
  • Do manually test Temperature & Pressure (T & P) relief valves on hot water heaters. (Note: This may cause T&P valve to leak; we recommend checking the manufacturer’s instructions or asking your plumber before testing the valve.)

The key to protecting our drinking water is having proper backflow prevention measures in place to guard against potential hazards and making sure backflow prevention devices are regularly maintained and tested as required.

Common Household Hazards

Submerged Hoses

Water held in pools, ponds or other vats open to the air and exposed to humans or animals may contain microbiological contaminants. Hoses submerged in pools or buckets can act as a conduit for contaminants under backflow conditions.

Chemical Spray Applicators

The chemicals used on your lawn and garden may be toxic or fatal if ingested. These chemicals include pesticides, herbicides, and fertilizers. Strong cleaning chemicals used to wash vehicles, house siding, etc. may also cause illness if ingested.

In-ground Lawn Irrigation Systems

In-ground irrigation systems often have puddles of standing water around the ground-level sprinkler heads. The sprinkler heads are not designed to be drip tight under backflow conditions. The standing water may contain microbiological contaminants, such as animal waste or chemical residues from the products applied to the lawn.

Hose Bib Vacuum Breaker

Hose bib vacuum breakers are simple, low-cost devices that should be used to help prevent backflow of water and possible pollutants or contaminants to the water supply.

A hose bib vacuum breaker consists of a spring-loaded check valve that seals against an atmospheric outlet when the water supply is turned on. When the supply is turned off, the device vents to atmosphere, thus protecting against backsiphonage conditions.

A diagram of a hose bib vacuum breaker is illustrated below:

hose bib vacuum breaker Click image to enlarge.

Note: Be advised if a vacuum breaker is installed at a hose connection and the hose is left charged with a closed spray nozzle, the vacuum breaker will not operate. DO NOT leave hose charged with or without a vacuum breaker.

Diagrams found on: University of Florida IFAS Extension

WARNING: Installation of a backflow prevention device could cause thermal expansion resulting in potential serious bodily injury and/or property damage. When installing a backflow prevention device, you must consult with a professional plumber to protect against thermal expansion AND ENSURE ALL NECESSARY PRECAUTIONS ARE TAKEN. For more information on thermal expansion, please visit our Thermal Expansion section under Cross Connection Control and Backflow Prevention in this website.