Jefferson Parish officials said Tuesday they expect a boil-water advisory for residents on the parish's west bank outside of Gretna and Grand Isle to be in effect until about noon Wednesday.
The Jefferson Parish Water Department issued the precautionary advisory Tuesday morning after a contractor replacing valves in the system at Ames and Lapalco boulevards caused a drop in pressure at the West Bank Water Treatment Plant.
Parish spokeswoman Samantha DeCastro said the pressure dropped below 20 pounds per square inch for less than a minute, prompting the advisory.
When the water pressure drops below 20 psi, it becomes possible for bacteria to get into the system. Samples must be tested by the Louisiana Department of Health and Hospitals for possible contamination, a process that takes 24 hours.
Tom West, the parish’s water director, said early indications were that a pocket of air made its way into the system from the work site when the valves were opened, registering a drop in pressure in a few spots throughout the system.
One of them was in the water plant that serves West Jefferson, requiring the parish to issue the advisory.
West said the water treatment process was working perfectly throughout the episode, and the operator noticed the drop and made adjustments quickly. He said water towers, which assist in maintaining water pressure, may also have contributed to the short duration of the decrease.
Gretna and Grand Isle have their own water treatment systems and so were not affected.
During a boil-water advisory, residents are urged to use bottled water or to boil or disinfect the tap water before using it to drink, make ice, brush their teeth, wash dishes or prepare food.
The Jefferson school system said Tuesday it was delivering bottled water and safely prepared meals to all impacted schools and had shut off water fountains and placed hand sanitizer in restrooms.
For residents, water should be allowed to boil for at least a minute; the resulting flat taste can be eliminated by shaking the water in a clean container or pouring it back and forth between two of them.
If disinfecting, residents should thoroughly mix ⅛ of a teaspoon of unscented, liquid chlorine laundry bleach with 1 gallon of water and let it stand for at least 30 minutes prior to consumption.
People with severely compromised immune systems, infants and some elderly people may be at increased risk and should seek advice about drinking water from their health care providers, the parish said.
While Orleans Parish has had 17 boil-water advisories since 2012, they are considerably rarer occurrences in Jefferson.
Jefferson was one of several parishes that issued a boil-water advisory in January 2018 after a three-day freeze had tens of thousands of customers dripping their faucets, creating a drop in water pressure.
Before that, there was an advisory for a single street in Grand Isle in 2014, and another for West Jefferson in 2008 because of a power outage at the plant.
Before that, there was a parishwide boil-water advisory for Hurricane Katrina in 2005.
“This is not a normal occurrence for the parish,” DeCastro said.
