Earl Gumbs spent most of Tuesday morning filling pots and trash cans with water at his home in Hillcrest Heights.

When Gumbs, 82, wasn’t stockpiling water, he and his wife were calling their elderly neighbors to make sure they knew they soon would be losing water because of emergency repairs to a water main serving southern Prince George’s County.

“A lot of people here don’t have Internet, so we are using our telephone tree . . . ,” said Gumbs, president of the Hillcrest-Marlow Heights Civic Association. “We’re coping as best as we can, but the real test has not come yet.”

Sweeping water from supermarket shelves, pouring it into plastic containers and delivering it to prized begonias, thousands of people prepared Tuesday for up to five days without ready access to a commodity that nearly everyone takes for granted.

In Forestville, a crew of workers gathered across from an apartment building preparing to replace a water main that serves more than 100,000 people and that had started to fail just as the area was preparing for the hottest stretch of the summer so far.

“This is a terrible time for this to happen,” said Lyn Riggins, a spokeswoman for the Washington Suburban Sanitary Commission, said at the site in Forestville.

The fear that the main, measuring 41 / 2 feet across, might explode had a crew poised to dig down and replace it once the utility shut down the line.

Ronald Williams peered over from the apartments as the workers assembled and offered a more caustic observation: “That’s their fault,” he said. “But we can’t do nothing except complain about it.”

And get ready.

Timothy Countee spent the morning shopping for extra bottled water and fruit drinks for the 16 residents at two assisted-living facilities in Temple Hills that he operates with his wife, Brenda. They filled six bathtubs with water to use for flushing toilets.

Most of the patients at Canterbury House and Corkran House have Alzheimer’s disease or dementia and require daily baths, he said. “We can deal with one or two days pretty easily,” Countee said at the Giant supermarket in Marlow Heights. “But if it’s four or five days, we’d have to move them to a hotel or something.”

Muhammad Ahmad, manager of Cameron’s Seafood Market on Branch Avenue in Temple Hills, said he needs water to clean fish, wash dishes and steam crabs for the carryout restaurant. He plans to investigate where he can buy ice to restock the ice machine and how he might get a water-tanker truck during any shortages.

And he’s worried about how the business would pay its 18 employees if it had to close.

“If we can arrange for hot and cold water,” Ahmad said, “then we can stay open.”

The rush to find bottled water had Sherrie Lapoint of Temple Hills instructing her 6-year-old granddaughter, Cherish, to scramble up the shelves at the Giant in Hillcrest Heights in order to reach the final few dozen bottles on the shelf.

“Can you imagine a real emergency?” Lapoint said. “I never even thought about it before this. What if it was something other than a water-main break — a terrorist attack? Where would we get water from?”

Ethel Boyd, 62, of Temple Hills took 18 of the remaining bottles. She’s diabetic and didn’t want to take any chances. “I have to drink a lot of water to keep my sugar down. I have to be careful,” she said.

The retired Georgetown University custodian marveled at the day’s predicament. “You never know when you’re going to have a water attack. I didn’t expect this today. Water’s important!”

Geraldine Bryant of Temple Hills, who is almost 70, had a somewhat more relaxed strategy: She filled up two crab pots at home, along with four bottles. The retired nurse didn’t succumb to the panic. “It’s a small thing, depending on how long it lasts,” she said. “If it’s a couple days, it won’t be too bad.”

Beverly Bland stopped her Chevy at the entrance of Prince George’s Pine Plains community and poured a gallon of water she had in her trunk onto her beloved wax begonias and purple-and-yellow impatiens.

The barrel of flowers welcomes people to her Temple Hills neighborhood, and the retired federal worker hated the idea of them going thirsty and shriveling in the heat.

“It’s not enough,” she said, standing in the searing sun. “We’ll see how long it’s off.”

Her husband, Jim, trekked to a Target in Alexandria on Tuesday to buy several more jugs of water.

The Blands figured they had enough water to last a couple of days.

“I can take a bird bath,” she said. But, given her daily exercise regimen, that won’t last. “When I really have the need and I can’t shower, I’ll have to go somewhere.”

Miranda S. Spivack and Trishula Patel contributed to this report.