At 2:59 a.m. on Saturday, Hassan Saleh got an e-mail from the University of Toledo in Ohio: “A ban has been placed on tap water in Lucas County.”

“At first I was sort of dismissive,” said Saleh, a 27-year-old graduate student studying microbiology at the University of Toledo.

In the wee hours of the morning, Jeanne Borer, 52, told The Washington Post she was waiting for a local food mart to open so she could buy coffee. Given the news, she decided to pick up some water while she was there.

Within hours, some 400,000 others were waking to the warning from city officials: Don’t drink tap water. Don’t use it to brush your teeth, bathe or cook. Don’t give it to pets. Don’t boil it — that will only increase the concentration of toxins in the water. Doing these things could “result in abnormal liver function, diarrhea, vomiting, nausea, numbness or dizziness.”

Sewage from septic systems, fertilizer from farms and waste from livestock pens had washed into Lake Erie, the warning stated, triggering an algae bloom that turned the lake’s water into something resembling pea soup. It’s a problem that reportedly had been cooking for more than a decade.

Early Monday, Ohio Mayor D. Michael Collins (I) announced that although tests done by state and local authorities show a positive trend, more testing is needed — dragging the water ban into its third day.

“The test results have been getting pushed back for 48 hours now,” Janet Fennell, 50, told The Post on Sunday night. “It’s just a waiting game.”

Saturday morning, Fennell said, she immediately ran to the grocery store but, by the time she got there at 7 a.m., bottled water was long gone.

“We were told water was sold out all the way up to Angola, Ind.,” she said. “We wound up driving to Sturgis, Mich., an hour and a half one way from my house.” Water was so difficult to find, some started price gouging.

“Some were charging $14.99 per case of water,” she added.

Gov. John Kasich (R) declared a state of emergency. The National Guard trucked in vats of H2O. Distribution centers popped up at area high schools and fire stations. The mayor asked grocery chains to divert water shipments to the area. Restaurants closed. Hospitals put together contingency plans — canceling elective surgeries and sending equipment that needed to be sterilized to facilities outside the toxic water zone, Bryan Biggie, disaster coordinator for Toledo’s ProMedica hospitals, told The Post.

Biggie said the hospital system brought in large pallets of water, shuffled medical staff to other facilities as needed and reverted to a non-water based food menu including things like sandwiches and chips. It delayed hundreds of elective surgeries, instead directed all efforts toward urgent care, labor and deliveries and more pressing matters such as heart and brain surgeries. And although the affected hospitals saw an anecdotal increase in the number of emergency room visits over the weekend, Biggie said, the hospital did not know if any of those were related to the water toxins.

Late Sunday night, Biggie said the hospital system remained “guardedly optimistic” as the panic subsided. “It’s just an end to the crisis,” he said. “We still have a lot to do to return to a normal business state.”

But while residents waited for the test results Sunday night, some weren’t ready to let their guard down.

“They told us we can now shower now if we shower quickly, and we can do laundry with cold water but the toxins will remain in our clothes. I’m not comfortable. I don’t want to get the water in my eyes or on my lips. But I guess I’ll have to,” said Fennell, a nursing student who is taking her state boards Monday.

Sunday night, Borer said her family had resumed showers and laundry.

“I haven’t,” she said. “I’m still using bottled water. I’m bathing in a liter of water a day.”

Borer, a medical assistant at a family physician’s office, said she’s not sure how the medical staff will handle the water crisis Monday morning.

“Probably a lot of hand sanitizer,” she said.