A cross connection exists wherever your home’s drinking water system could potentially contact contaminated sources. Every home contains these vulnerable points where water pipes and plumbing fixtures create pathways for contamination to enter your drinking water.

Types of Cross Connects

Garden Hose Spigots

Garden hoses represent the most common type of cross connection in residential settings. When a hose end is submerged in water containing chemicals, fertilizers, or other contaminants, it creates a direct pathway for contamination to enter the water system. Sudden pressure drops caused by water main breaks, firefighting operations, or high system demand can create siphon conditions that draw contaminated water back through the hose into both household plumbing and the public water supply. Installing a simple, inexpensive vacuum breaker on outdoor faucets or hose connections provides effective protection against this hazard. Homeowners should never leave hose ends submerged in pools, sinks, containers, or any standing water to prevent potential contamination of the water system.

Hose spigots should have built in vacuum breaker or an add-on vacuum breaker.

Water Softener or Water Filtration Systems

In Nebraska, water softeners and water filtration systems are required to have an air gap on their drain line. This is a crucial plumbing code requirement designed to prevent backflow and contamination of the potable water supply.  The air gap must be at least two times the diameter of the drain line, but in no case less than one inch above the top of the receptacle used for drainage.

Lawn Irrigation Systems

Lawn irrigation systems require backflow prevention due to the high risk of cross-contamination between potable water and non-potable sources. These systems create multiple hazardous conditions: sprinkler heads sit at or below ground level where they contact fertilizers, pesticides, herbicides, and contaminated soil; stagnant water in distribution lines can harbor bacteria and other pathogens; and chemical injection systems for fertilizers or pesticides can directly introduce toxins into the water supply. During pressure drops or water main breaks, contaminated water can be drawn back into the municipal system through siphonage, potentially affecting the entire neighborhood’s water supply.

Typically the backflow preventer will be installed on the on outside of the house and will look something like this.

Swimming Pool or Hot Tub

Pools and hot tubs with permanent plumbing connections create direct cross connections that require proper backflow prevention devices. Without adequate protection, these connections can allow pool water containing chemicals and contaminants to be drawn back into both your home’s plumbing and the public water system.

When using a hose to fill pools or hot tubs, the hose end must never be submerged below the water surface, as this creates an additional cross connection hazard. An air gap must always be maintained when filling any pool, hot tub, or water container.

Private Wells and Secondary Water Sources

Private wells and secondary water sources, such as sand point wells used for irrigation, create serious cross connection hazards and are prohibited from being connected to the SID 5 water system. These alternative sources may contain contaminants including bacteria, chemicals, minerals, or other pollutants that do not meet drinking water standards. Without proper backflow prevention, pressure fluctuations or system failures can cause untreated well water to flow back into the potable water supply, potentially contaminating the entire distribution system.

Home Medical, Dental or Dialysis Equipment

Home medical, dental, and dialysis equipment create high-hazard cross connections due to potential contamination from bodily fluids, medications, and toxic cleaning chemicals. All home medical, dental or dialysis equipment connected to a water supply must have a backflow preventer installed.

Boiler Systems for Heating or Water to Air Heat Pump

Although not common, boiler systems and water-to-air heat pumps require backflow prevention due to potential contamination from system chemicals and non-potable water conditions. These closed-loop systems often contain corrosion inhibitors, antifreeze, biocides, and other chemical additives that are toxic if ingested.

Other Possible Cross Connections

There are dozens of possible cross connects. If a piece of equipment or device is connected directly to the water system it should have a backflow preventer installed. Some examples are: