Backflow is the undesirable reversal of the flow of water from its intended direction in any pipeline or plumbing system. Backflow is dangerous because it can allow drinking water in plumbing to become contaminated and unusable.


Backflow preventers are mechanical plumbing devices installed in a plumbing system to prevent water from flowing backward in the system. A properly installed, tested and maintained backflow preventer at the service entrance to a building or property can reliably prevent the backflow of water of an unknown quality from flowing back into the community water system.




In adherence to Colorado’s regulations, the Cross-Connection Control and Backflow Prevention Program protects the public water system from cross-connection contamination by requiring customers to install containment assemblies, (also known as backflow prevention assemblies or, for residential homes, dual check valves) containment devices or backflow prevention devices. Health and well-being are important and directly related to good water. The water quality is monitored closely from the time water first enters the treatment plants to the time it exits your water faucet.


A backflow preventer is installed to protect the public water supply against possible hazards in the customer’s plumbing system. The actual or potential cross connection belongs to the property owner and not to regulatory officials or to the water utility. Once the water goes beyond the meter, water quality could be altered. The water utility does not want the water back, nor do the customers want to purchase used water. If a backflow preventer is required to keep the water safe, then the person who created the cross connection (actual or potential) should purchase, install or maintain the backflow preventer.




A plumbing cross-connection is defined as any physical connection or arrangement between potable water and any source of contamination. Any pipe, valve, fixture, etc., in a water plumbing system that may allow drinking water within the system to become contaminated or questionable in quality. Cross connections can either be eliminated or protected by an air gap or mechanical backflow prevention.


Examples of cross-connections

  • In bathtubs, where the faucets may enter through the wall of the tub below the top, an overflow provided below the faucets will prevent cross connection
  • Water softeners, washing machines and dishwashers connected to a building drain without an air gap and water powered backup sump pump systems that use municipal water pressure and a venturi (a short, narrow tube between wide sections for measuring flow rate or exerting suction)to evacuate water from the building or its sump pit.
  • Garden hose cross-connections can occur when someone improperly connects a hose directly to a sewage waste pipe for any reason which have been found like this as building piping drains, water softener drains, boiler drains, etc. Cross-connection can also occur when leaving a garden hose in a position to allow waste water to flow back into the supply plumbing system, for example, leaving the hose in a pail of water. Back-flow preventers on the hose bib can prevent this from happening.
  • Water powered sump pumps can form unsanitary cross-connection between ground water or basement water leaks and the building municipal water supply piping – and thus are illegal in some plumbing jurisdictions.




A backflow preventer is a check valve installed on potable water supply piping to prevent possible contamination of the water supply system. Check valves at the right location on water system piping are a good idea and are required by national and local plumbing codes. In a home served by public or municipal water from a public water main, the home should have a backflow preventer to make sure that potentially unsanitary water from an individual home’s piping never flows backwards into the public water mains.


Private well water systems should have check valves and backflow preventers, principally to prevent loss of well pump prime and to prevent the back-flow of water out of the pressure tank into the well when the pump is not running. Check valves used on well water system piping are used to hold pressure in the system when the pump stops. Check valves on well piping also prevent backspin of the well pump, water hammer and up-thrust inside the pump. These problems can damage the well pump.


Check valves are used on sump pump drain lines to prevent back-flow of water from the sump pump exit piping into the pump pit when the sump pump turns off. They are also used on sewage pumps to prevent back-flow of sewage into the building piping or sewage pumping chamber from a sewer main (or septic tank) located higher than the building.


In order to have your backflow devices inspected, tested or repaired you can go to your local town or city’s website to find out more information and to find a certified Cross-Connection Control technician recognized by the State of Colorado.


Call Ace Hi Plumbing, Heating & Air if you would like to schedule an installation or replacement of a backflow preventer. We have trained technicians and service the Northern Colorado area including Loveland, Fort Collins, Berthoud, Longmont, Johnstown, Greeley, Evans and Estes Park.