Water-powered Sump Pumps-Backflow Preventer

With the many storms we have been having that involve the loss of electrical power, this office has been receiving many calls about what type of backflow preventer is required on the water supply to the new type of water-powered back-up sump pumps.

Manufacturers recommend that a water-powered sump pump be used as a backup sump pump for the primary electric sump pump. The discharge from the water-powered sump pump must discharge to the outdoors. Manufacturers state that the discharge not be connected to the discharge from the main pump. It will cause the main pump to send water back into the pit and a spill from the backflow preventer will occur.

Since these pumps could be subject to a back siphon condition, a proper backflow preventer must be installed on the water supply to the pump. Not knowing what might enter the sump pit, a reduced pressure zone backflow preventer is the proper backflow preventer to use.

This could conflict with some of the manufacturer's recommendations which only require an atmospheric vacuum breaker. In that case, the Uniform Construction Code (UCC) would override the manufacturer's instructions. Check to be sure that the ejector pump is not set into the sump pit. These units are not made to be submerged.

Finally, a plumbing technical section is required for the installation of this system. It is very important to ensure that the proper backflow preventer is installed and that the pump discharge is not connected to the primary sump pump discharge piping. Connection to the primary pump discharge would be a violation of the manufacturer's installation instructions.


Thomas C. Pitcherello
Code Assistance Unit
(609) 984-7609

Construction Code Communicator,Volume 23, Number 3, Fall 2011 (PDF)