Richmond Mayor Danny Avula announced Thursday shortly after 12 p.m. that the city's water system is now "fully pressurized."

The city is divided into nine zones, and all nine had to reach that mark before testing could begin to lift the boil water advisory established on Monday after a power outage led to significant damage at the city's water plant.

To lift the advisory, the city must submit water samples clear of contamination 16 hours apart.

Avula said the city believes that the presence of contamination is "a very low probability."

"I'm feeling very optimistic about this, but we need to work through the testing protocols with our partners at VDH," he said, referring to the Virginia Department of Health.

"If things continue with this pace and everything looks good, we should be able to lift that boil water advisory sometime between tomorrow and Saturday."

Avula said five pumps remain active, and are now producing 72 million gallons a day, which is above the average utilization at this time of year of 45 million gallons per day.