Backflow Program

Mechanical backflow prevention assemblies have internal seals, springs, and moving parts that are subject to fouling, wear, or fatigue.  Also, mechanical backflow preventers and air gaps can be bypassed.  Therefore, all backflow prevention assemblies have to be tested periodically to ensure that they are functioning correctly.  Mechanical backflow prevention assemblies have to be tested with properly calibrated gauge equipment.

In order to ensure the proper operation of a backflow prevention assembly, it must be tested and certified upon initial installation and at least once a year thereafter by a licensed backflow tester.

A cross-connection is any temporary or permanent connection between a public water system or the customer’s potable water system and any source or system containing non-potable water or other substances.

Common cross-connections

• Private Wells – where the private well connection is connected to a service line receiving water from a public water supply.  The untreated water could be pumped into the potable water supply which serves the home and the public water system.
• Lawn sprinkler systems – where the stagnant/contaminated water from the sprinkler system could be drawn into the drinkable water supply for your home.

A backflow prevention assembly is a means or mechanism to prevent backflow.  The basic means for preventing backflow is an air gap, which either eliminates a cross-connection or provides a barrier from backflow.  The basic mechanism for preventing backflow is a mechanical backflow preventer, which provides a physical barrier to backflow.  The principal types of backflow preventers are the reduced-pressure principle assembly, the pressure vacuum breaker assembly, and the double check valve assembly.

Back-siphonage is backflow caused by negative pressure (i.e. vacuum or partial vacuum) in a public water system or customer’s potable water system.  The effect is similar to drinking water through a straw.  Back-siphonage can occur when there is a stoppage of water supply due to nearby firefighting, a break in a water main, etc.

Backflow refers to the reverse flow of non-potable water, or other substances, through a cross-connection and into the piping of a public water system or customer’s potable water system.  Two types of backflow are backpressure backflow and back-siphonage.

Backpressure backflow occurs when the downstream side of the piping system is greater than the supply pressure in a public system or customer’s potable water system.  Backpressure can result from an increase in downstream pressure, a reduction in the potable water supply pressure, or a combination of both.  Pumps can create increases in downstream pressure; temperature increases in boilers, etc.  Reductions in potable water supply pressure occur whenever the amount after being used exceeds the amount of water being supplied, such as during waterline flushing, firefighting, or breaks in the water mains.

These programs safeguard the public drinking water and protect the health of its residents.  They do this by helping to ensure that any contaminants that could backflow into the public water supply system are isolated within the internal distribution system. Failure to comply with annual testing could result in the city disconnecting water service until the backflow device is tested.

Yes. Potable water supply to lawn irrigation systems shall be protected against backflow by a pressure-type vacuum breaker, a double-check valve assembly, or a reduced pressure principle backflow preventer – depending on the degree of the site hazard. To obtain an irrigation/backflow permit, please visit the Longwood Portal Page or contact the Public Works Department at 407-263-2382.

Only Licensed testers are authorized to test backflow prevention assemblies. The City of Longwood conducts backflow testing only (no repairs) for a fee of $40. You can also contact a licensed plumber. A list of licensed testers can be found here. Fees can differ depending on the testing company, quantity of backflow prevention assemblies to be tested, number of locations, etc. In general, expect between $50-$200 per assembly. 

Email the report to the Backflow Program.

No, the installation, repair, replacement, and/or testing of in-scope testable backflow assemblies must be performed by a licensed contractor.  Other un-related plumbing tasks can be performed by a homeowner, but not activities relating to backflow prevention devices.