Backflow Testing in Rockville, MD

Is my Rockville address on City water or WSSC Water?

It depends on the street. The City's own system, which treats Potomac River water at its plant, covers roughly 70 percent of Rockville, and WSSC Water serves the remaining addresses. Your water bill tells you which, and the City publishes a Water Service Provider Map that answers it by address. Some mailing addresses with a Rockville name also sit outside the city limits in unincorporated Montgomery County, where WSSC is the provider. Knowing the answer first saves time, because backflow rules and plumbing permits follow the water provider.

What does WSSC require if my home is on WSSC water?

WSSC's cross-connection control program wants every testable backflow prevention assembly tested once a year by a plumber who holds WSSC cross-connection technician certification. A registered principal master plumber sends the result to WSSC electronically. WSSC mails reminder letters to customers with assemblies on file, and the program can be reached at 301-206-4004. Lawn sprinkler devices are the most common residential case; fire sprinkler and commercial lines can carry assemblies too. WSSC-water addresses also get their plumbing permits from WSSC.

What if my home is on City of Rockville water?

The City runs its own water utility, so its rules govern cross-connections on its system, and WSSC's reporting process doesn't automatically apply. Before you book a test on a City-water address, call the City's utility staff and ask whether your device must be tested and where the report goes. Plumbing permits for City-water addresses come from the City's Department of Community Planning and Development Services (CPDS), which takes applications online. A plumber who works in Rockville regularly will know both systems and can help you sort out which set of rules is yours.

A note on Rockville homes

The median Rockville home was built around 1980, so the city mixes postwar subdivisions in areas like Twinbrook with newer construction near Town Center and along Rockville Pike. Older lots often got sprinkler systems as later additions, and a device that has sat through many winters is a likely candidate for a rebuild. If one is leaking before you know which system serves you, close the sprinkler shutoff and leave the device alone until the plumber arrives.