Millions of people in Montgomery and Prince George’s counties are urged to only use water for essential tasks because of a power issue at a WSSC Water filtration plant.

A power outage at the Potomac Water Filtration Plant, WSSC’s largest plant, affected the plant’s ability to operate, the utility company said Tuesday morning. That plant supplies drinking water to 1.9 million WSSC customers.

Power has been restored to one of two power feeds the plant uses, but the process to bring all of the systems back online takes time, WSSC said just before 1 p.m. The utility said customers should still conserve water until normal water production has resumed.

WSSC asked customers to do the following to conserve the water that has already been treated:

Take shorter showers and quickly turn off faucets immediately after use

Do not use any water for plants and grass outside, including lawn irrigation systems

Limit flushing toilets (i.e. do not flush after every use)

Limit using washing machines and dishwashers

As of now, WSSC said the water is safe and there’s no need to boil it before use. WSSC said it’s asking its customers to conserve water to try and prevent the need for a future boil water advisory in the area.

WSSC said it’s working with Pepco to restore power to the Potomac plant as quickly as possible.

In response to a question from News4, WSSC said the power issue was not the result of a cyber attack.

The plant draws water straight from the Potomac River and produces between 100 and 120 million gallons of drinking water per day, WSSC said.

Another WSSC plant is still operational and currently producing 90 to 95 million gallons per day, but that’s not enough to meet the 170 million gallons per day needed to meet demand, the utility said.