Backflow Incidents

Backflow Prevention Helps Protect Our Drinking Water

Backflow incidents in recent years like the ones below can threaten public health. As a community, our efforts to control cross-connections and to prevent backflow help keep our San Diego County water supply safer and more secure. When installed properly and maintained routinely, backflow preventers reduce the risk of water-borne health problems. While incidents of backflow do occur, they are happening less frequently. Click on dates for full stories, and please let us know if any links are broken.

September 3, 2024

Grand Prairie, TX
The drinking water supply in Grand Prairie was contaminated by a foaming agent. Residents were unable to use tap water for drinking, cooking, bathing or anything else other than flushing toilets. This was the result of a chemical fire suppression agent that was pumped into the water system through a malfunctioning backflow prevention valve during firefighting efforts in the area.

May 23, 2023

Waterville, ME
Firefighters responded to a fire on the fourth floor of a multi-story apartment building. To contain the blaze they pumped through the fire department connection (FDC) into the building's sprinkler system with a suppression foam. Due to the improper location of the building's backflow preventer within the fire sprinkler system, this foam contaminated the community water supply. Kennebeec Water District issued a boil water advisory warning nearby residents to use only bottled water for cleaning, food prep, and all other domestic needs. The water district worked quickly to implement flushing and water sampling protocols so the wider community would be protected. Unfortunately this fire directly resulted in injury to several people and one fatality.

February 20, 2022

Castroville, TX
A water main break caused the City’s water pressure to drop below 20 psi. This sudden, low water main pressure can result in backflow from higher pressure parts of the distribution system and of all types of water users, possibly allowing contaminants to enter the drinking water through unprotected cross-connections. City officials advised the water system customers to boil water and allow it to cool prior to washing hands, brushing teeth, drinking, cooking or other uses.

October 11, 2019

Byron, GA
Routine maintenance of a large diameter water main caused very low water pressure in an area of The City of Byron. This area of low pressure could draw water from surrounding, higher pressure areas, siphoning contaminants into the water distribution system. City officials advised residents to boil water prior to drinking, cooking or other uses.

July 26, 2019

Hillyard, WA
Residents found that their water meters were clogged with grass and seeds. Water coming out of the taps was green. They learned that a hydroseeding operation pumped fertilizer and seeds into the community water system through a fire hydrant. Community officials warned residents to avoid drinking the water due to the contamination.

September 12, 2017

Alameda, CA
Residents and businesses at Alameda Point complained about the look and taste of their water. The Water District found a cross-connection between the drinking water system and a non-potable irrigation well. The City issued a Do Not Drink / Do Not Use order for 268 residents and over 60 businesses over several days. Samples from the irrigation well contained elevated levels of total coliform bacteria with no measurable disinfectant, but did not contain any e. coli bacteria. The Water District permanently disconnected the well.

December 14, 2016

Corpus Christie, TX
City-wide water use ban issued when asphalt plant workers reported brown, milky, sudsy water on several occasions. After multiple efforts by city crews to flush contaminated water out of pipes, it was found that there was no backflow preventer between the potable water supply and the chemical mixing tank. Water testing at various points around the city revealed no contamination beyond the asphalt plant.

November 2, 2016

Culpeper, VA
Backflow of Antifreeze from the fire sprinkler system of a business leads to water distribution system flushing. Residents warned not to drink or cook with the water even though the propylene glyco antifreeze is non-toxic.

August 4, 2016

Jacksonville, NC
Faulty backflow prevention device allows swimming pool water to contaminate drinking water lines. Boil water advisory issued while water district flushed lines and the backflow preventer was replaced.

July 28, 2015

Corpus Christi, TX
E-coli found in the city water was traced to a neighborhood of properties which have private wells and sprinkler systems without backflow prevention assemblies. Contaminated water was able to flow into the community water system from these properties because there was no backflow protection maintained between them and the water district.

July 21, 2012

Lubbock, TX
Power Outage leads City Officials to issue boil water order. Loss of power crippled water distribution pumps, resulting in low pressure and potential for backflow of contamination or pollution into the drinking water supply

June 1, 2011

Somerset, Mass.
Hydro-Seeding Contractor direct connects to fire hydrant, pumping seed material and chemicals into water main, poisoning City drinking water system