City Assistance Program for Sewer Backflow Prevention

The City of Alexandria offers assistance to homes that may have experienced a basement back up or flooding after a heavy rainfall and are interested in having a licensed plumber install a backflow preventer.

Page updated on Nov 4, 2021 at 10:51 AM

The City of Alexandria sewer Backflow Preventer (BFP) Assistance Program reimburses homeowners for up to 50 percent of the cost of installing a BFP device by a licensed plumbing contractor, up to a maximum of $2,000. The program is open to all City of Alexandria homeowners. The City offers assistance only to those residents who have submitted an application and have been approved reimbursement.


Basement back-ups or flooding can occur when water from a heavy or intense rain flows into the sanitary sewer system. The sanitary sewer system is a network of pipes and manholes in City streets that collects wastewater from homes and businesses. The wastewater collected is transported for treatment to the plant operated by Alexandria Renew Enterprises. The plant is located along the beltway at the foot of S. Payne Street. Homes and businesses are connected to the sanitary sewer system by a house sanitary sewer also called a house lateral or lateral sewer.

Rainwater can enter street and house sewers through cracked pipes or leaky joints and manholes. Sometimes homes and businesses connect sump pumps and roof downspouts to the sanitary sewers – these connections are not allowed and discharge unwanted storm water to the sanitary sewers during rain events.

Backflow images

If the amount of rainwater entering the sanitary sewers is excessive, the street sewers become overloaded and can back-up into the basements of homes and businesses. You can see a map of areas subject to sanitary sewer backups by clicking here

Protection for Your Home or Business

A modification to the internal plumbing within a home or business can provide a measure of protection against basement back-ups.

A common protective device called a backflow preventer (BFP) can be installed within the plumbing system to effectively shut-off the home or business from the street sewer system during sewage back-ups.

How a BFP Protects Against Basement Back-Ups

Backflow image 3

A BFP can function automatically or be operated manually by the resident. An automatic BFP can be equipped with a battery operated light (much like a smoke alarm) to tell the resident when it is open or closed. To protect, the BFP must be closed during the sewage overload period. This period varies depending on the size of storm, but generally lasts from 2 to 6 hours.

Some of the things to consider when deciding to install a BFP in your home or business include the following:

  • Will someone be home when the protection is needed? This answer may help select between an automatic or manual device. 
  • I won’t be able to use my plumbing system when the BFP is closed and; I can’t have flowing connections (e.g. a sump pump or downspout) discharging upstream of a closed BFP. 
  • I should get a quality product, one that doesn’t leak and is easily maintained.

Deciding to Install a BFP

If you decide to install a BFP, we suggest that you consult a plumber licensed by both the State and City. The plumber can help you determine the most appropriate application and installation arrangement of a BFP for your situation. The property owner/plumber will be required to obtain the appropriate installation permits from the City.

Alexandria's BFP Assistance Program

The City has instituted a cost reimbursement assistance program for property owners who decide to install BFPs. The program began on July 1, 2018, and will continue through 2022, subject to available program funding. The City will reimburse an eligible property owner 50% of the total BFP installation cost, up to a maximum of $2,000. Qualifications for reimbursement include the following:

  • Property must have a basement (finished or unfinished) 
  • Plumber licensed by the State and City must install the BFP device 
  • City must be granted access to verify installation 
  • Owner/plumber must have obtained an installation permit and an approved final inspection 
  • Owner and installer must certify to payment in full 
  • Owner must accept responsibility and release City

Applying for Reimbursement

If you decide to install a BFP, use the form to obtain the reimbursement allowance. The completed application along with a copy of the paid in full invoice or receipt can be mailed/delivered to:

Department of Transportation and Environmental Services
Permit Section 
301 King Street 
City Hall Room 4130 
Alexandria, VA 22314

For program questions, please call: 
Transportation and Environmental Services 
Sanitary Infrastructure Division 

For information on installation permits, please call: 
Department of Code Enforcement