The Sewerage & Water Board of New Orleans warned residents Monday that water pressure could drop on the city's East bank as a contractor tied one of two huge water towers into the water system.

Crews lowered a huge valve into the ground Monday afternoon, an essential piece of equipment needed to fill the tower with water. Work began in earnest this week to get the second tower, located behind Harrell Park off Leonidas Street, tied into the S&WB water system.

The city received $50 million in hazard mitigation funds from the Federal Emergency Management Agency, or FEMA, to construct the towers after a series of boil water advisories stemming from a loss of S&WB power.

Problems with the agency's power generation system were detailed in a WWL-TV investigative special "Down the Drain."

The water towers stand 200-feet tall, new construction looming large over the agency's aging power and water treatment plants off Claiborne Avenue. The towers are designed to hold 4 million gallons of water, enough to keep water pressure up in the system for 40 minutes in the event of another power outage.

Last fall, when the S&WB lost its only working power-generating turbine, it took workers 20 minutes to switch the water, sewer and drainage systems over to Entergy power, leading to the latest boil water advisory.

The towers would buy the agency time.

When the system loses pressure, bacteria can creep into the drinking water. Officials urge residents to boil their water until tests come back clear of coliform and other bacteria.

Preventing boil advisories is an added benefit of the tower construction, however. They are designed to prevent what's called "water hammer," when the water pressure rapidly changes, leading to massive vibrations in the pipes.

Those vibrations can cause more damage to a water distribution that is estimated to leak more than 40 percent of the water being pushed through it.

Crews have to close off some parts of the water distribution system to tie the tower in. Contractors tested the closure in recent weeks, and a spokeswoman said they received no reports of water pressure loss.

But the S&WB encouraged residents to report low water pressure through Friday, Dec. 1 by calling 52-WATER.

Correction: A previous version of this story included incorrect information from a S&WB spokeswoman that one of two water towers had already been tied into the S&WB system. Neither tower was connected to the water system at the time of publication.