Q: How do I know if this water problem affects me?

A: The Prince George’s County communities affected include Morningside, Hillcrest Heights, Camp Springs, Forest Heights, Temple Hills and Oxon Hill. Joint Base Andrews and National Harbor also are affected. The Washington Suburban Sanitary Commission’s interactive map, at www.wsscwater.com, shows the affected area. You can type an address into the search box to see if there are water restrictions.

How much water do I need to have on hand?

WSSC officials recommend at least two gallons of water per person, per day, to last at least “several days.” Water stored in bathtubs and sinks can be used to flush toilets.

When will I lose water?

The utility said the pipe was to be shut off late Tuesday night or early Wednesday. There is enough water in the system to keep water flowing for 12 to 15 more hours. However, the WSSC imposed mandatory water-use restrictions Tuesday night to keep that water flowing for as long as possible and to maintain water pressure in the system so fire hydrants work.

What should I do — or not do — during the mandatory water restrictions?

All residents and businesses in the affected area must stop all outdoor water use — no watering lawns or plants, no washing cars, no topping off swimming pools. Take shorter showers, limit faucet use and refrain from flushing every time. Also, delay using washing machines and dishwashers.

When will I get my water back?

WSSC officials said they expect the repairs to take up to five days.

If I am not in the affected area, do I need to do anything? Would it help if I conserved water, too?

People outside the area do not need to conserve, WSSC says.

Is the water now coming out of my tap safe to drink?

Yes, WSSC officials say.

What if this is the first I’m hearing about the problem and I didn’t stockpile any water?

Grocery stores said they have ordered extra shipments of bottled water to keep up with demand. But store shelves began to empty Tuesday afternoon, so you might need to hunt for it. Local officials also asked that people in the affected areas check on neighbors, particularly the elderly.

How did the WSSC know that the underground pipe was about to burst?

Fiber-optic cables installed in the pipe this summer picked up the “pings” of the main’s reinforcing steel wire beginning to break from corrosion. The pings began July 12 and then picked up, totaling 30 pings as of late Monday night. Too many wire breaks in one place signal a weak spot where the pipe could soon break.

— Katherine Shaver