Aquarion Water Co. has instituted a mandatory ban on outdoor watering for its customers in Mystic and Stonington.

In an announcement Friday afternoon, the company said it instituted the ban in cooperation with Stonington town officials. The ban includes use of irrigation systems, sprinklers and soaker hoses.

It is effective immediately. 

In a news release, Aquarion said it will remind customers about the watering ban with automated phone calls.

Outdoor watering activities using a hand-held hose will be allowed for the time being, the company said.

“We are telling our customers to turn off their irrigation systems and sprinklers for the season,” said Charles Firlotte, Aquarion president and chief executive officer. “We are doing this to ensure that we have an adequate water supply for everyday use and fire protection.”

Previously, Aquarion customers had been asked to voluntarily conserve through notices and automated phone messages. The company serves about 8,800 people in Mystic and Stonington.

Connecticut’s drought level has recently been upgraded to a “severe drought” for most of the state due to an extended dry spell, according to the National Oceanic and Atmospheric Administration.

With below average rainfall and extremely high water demand, water levels in Aquarion’s reservoirs are continuing to decline, the company said. 

On Wednesday, the state's Interagency Drought Workgroup announced that a statewide Drought Advisory first issued on June 27 has been extended, and requested that residents voluntarily reduce water use by 10 percent.

For water conservation tips, visit www.aquarionwater.com/conserve.