Backflow is the undesirable reversal of flow of water or mixture of water and other liquids,
gases, or other substances into the distribution pipes of the potable supply by water from any
Any water or other liquid or gas flowing in the opposite direction from its normal flow…that is
backflow and it can put our water supply in danger.
RPZ / Cross-Connection or Backflow Preventer Devices:
What is backflow?
Backflow may be caused by conditions of gravity, vacuum or other pressure changes.  There
are two factors that contribute to reversal of flow in pipelines.  One is back-siphonage and the
other is backpressure.
Back-siphonage conditions exist when there is a negative or sub-atmospheric pressure in the
supply piping, allowing downstream substances to be siphoned into the potable water supply.
Under-sized pipes, pipeline breaks, and high withdrawal rates create vacuums, which contribute
to the occurrence of back-siphonage.
Backpressure conditions exist when a pressure higher than the supply is created in the
downstream piping, allowing downstream substances to be pushed into the potable water
supply.  Backpressure can occur when higher pressures downstream are generated by pumps,
thermal expansion and elevation.
When does backflow occur?
What is a cross-connection?
The term cross-connection refers to any unprotected actual or potential connection or
structural arrangement between a public or a consumer’s potable water system and any other
source or system through which it is possible to introduce into any part of the potable water
system any used water, industrial fluid, gas or substance other than the intended potable water
with which the system supplied.
By-pass arrangements, jumper connections, removable sections, swivel or change-over devices
and other temporary or permanent devices through which or because of which backflow can or
many occur are considered to be cross-connections.
What is the solution?
It is evident that we cannot eliminate either the occurrence of backflow nor can we prevent
cross-connections from being created.  We must therefore provide a means of protecting
drinking water systems from the hazards of backflow occurrences through cross-connections.
Mechanical backflow prevention devices and assemblies offer the best protection against cross-
connection hazards.  Backflow prevention devices prevent backflow by stopping the reversal of
flow, but are not testable once installed because they do not have inlet and outlet shut-off
valves or test cocks.  Backflow prevention assemblies include an inlet and outlet shut-off valve
and test cocks to facilitate testing of the assembly while it is in its functional in-line position.  
Furthermore, backflow preventers may be installed at the source of potential contamination or
on the water service line itself.
Some of the most popular applications for backflow preventers or RPZ units are irrigation
systems, restaurants, dentists, car washes, factories, beauty shops, day spas, nail salons,
doctors, funeral homes, veterinarian’s  office, auto body shops and many more.
Who can test your backflow preventer or RPZ unit?
Freedom Plumbing and Heating has a licensed CCCDI (Cross Connection Control Device
Inspector) technician on staff who is qualified to test and certify your devices.  FPH then files
all necessary paperwork with your local water management department, thus keeping you in
compliance with state and local laws.  
Not sure if you have a backflow preventer or if you need one?  Give FPH a call and let us help
you determine your needs.
1172 Sunbury Road
South Elgin, IL 60177-1846
847-695-5311 (telephone)
847-741-4874 (fax)
FPH provides friendly quality plumbing, heating, and air conditioning service to the Fox Valley and surrounding communities such as Algonquin, Aurora,
Batavia, Bartlett, Barrington, Carpentersville, Crystal Lake, Dundee, Elgin, Geneva, Hampshire, Hanover Park, Huntley, St. Charles, and Streamwood.