The New Orleans Sewerage & Water Board needs to provide immediate notification to residents when there’s a potentially dangerous problem with the city’s water supply, members of the City Council said Thursday in admonishing the agency for its slow response in issuing a boil-water advisory last week.

Council members called the agency’s leaders on the carpet over the seven-hour delay before that notice was issued Friday, saying that even though it turned out there was no danger, the slow response hurt businesses, frustrated and worried residents and could damage the city’s tourist economy.

“For over two decades we have put all of our eggs in the basket of tourism, and the tourist industry is, for better or for worse, our life’s blood,” said Jason Williams, who chairs the council’s Utilities Committee and called Thursday’s meeting.

“I think it goes without saying that clean, potable water is essential to that industry, and notices of any restrictions with regard to that water are equally essential,” he said. “And also to our taxpaying citizens and constituents, we owe a great debt to make sure they know up to the minute what’s going on and why it’s going on.”

S&WB Executive Director Cedric Grant said he agreed that the time between the loss of power and the notice was too long. He said new systems and policies have been put in place to provide quicker notice in the future.

A boil-water notice was in effect for the entire east bank of New Orleans for 31 hours last week, from 10 a.m. Friday to 5 p.m. Saturday.

“On a weekday morning when citizens are getting up, getting a shower, brushing their teeth, when businesses — especially restaurants and the like — are doing preparatory work, how could you wait so long to let us know?” Councilwoman Susan Guidry asked.

State and federal regulations require water systems to issue boil-water advisories anytime pressure in the pipes, typically at 68 pounds per square inch, drops below 15 psi, a threshold at which contamination by bacteria that can cause gastrointestinal issues and illness can occur.

Power surges at the Carrollton water treatment plant about 2:55 a.m. Friday caused pressure to drop at the plant and a brief loss of power at two pumping stations. Four hours later, crews arrived for work and checked pressure gauges at pump stations throughout the city, eventually discovering that seven of the 16 stations had recorded pressure drops that would require a boil-water advisory.

But an advisory wasn’t issued until 10 a.m., after officials had consulted with the state Department of Health and Hospitals.

Nearly every step of that process came in for criticism from council members, who said it should have been clear immediately that residents and businesses needed to be warned they should not drink the water.

“If you know the rule is anything at 15 or below 15, you need to do a boil water (advisory), why would you need to check with anyone before getting it out to people?” Guidry asked.

Grant said the S&WB was following its existing protocols and working to gather as much information as possible before putting out a notice.

Councilwoman Nadine Ramsey, who was critical of the S&WB for an even longer delay in notifying residents of water pressure issues in Lower Coast Algiers earlier this year, criticized not only the delay but the inability of residents to get through to a live operator at S&WB with questions during the advisory.

“I think people understand the system is old and events will happen, but they don’t understand why they’re not getting any information, and that’s a major concern we have to deal with,” Ramsey said.

The S&WB has taken steps to issue faster notices in the future, including adding equipment that allows pressure levels at the pumps to be monitored from the water plant in real time and ensuring that the executive staff is notified when pressure drops below 40 psi, Grant said.

It remains unclear exactly what caused the power surges that took the system offline. In its initial advisory, the S&WB blamed the surge on Entergy New Orleans.

But the power company said there were no problems on the two lines that feed power into the water plant. That suggests that whatever happened was on the S&WB’s end and beyond Entergy’s control, said Gary Huntley, the company’s vice president of regulatory and governmental affairs.

“If there had been a surge on that power, we would have detected it,” Huntley said.

The power issues are now being investigated by the S&WB, in collaboration with Entergy, and more information on what happened and how to prevent it in the future will be provided to the council when that review is complete, Grant said.

“We’re not sure what happened, but it’s happening more frequently than it needs to,” he said.

Follow Jeff Adelson on Twitter, @jadelson.