The Alexandria City Council yesterday imposed mandatory water conservation measures on city residents and ordered city police to begin enforcing the regulations on Wednesday.

The restrictions are similar to those that went into effect yesterday in Fairfax County. They sharply curtail the outdoor use of water.

Both the city and the county took action to curtail water use after the Occoquan reservoir, which supplies drinking water to 600,000 Northern Virginians, fell to about one-third of its capacity. Prince William County, which also draws water from the reservoir, has refused to imposs mandatory restrictions, but urged its citizens to conserve water voluntarily.

The restrictions passed yesterday in Alexandria prohibit:

Washington automobiles, trucks, trailers and other vehicles except in vehicle-washing facilities that have a recycling system or by persons using a three-gallon or smaller container.

Washington streets, driveways, parking lots, service station, aprons, office buildings or the outside of homes or other outdoor surfaces.

Watering outside shrubbery, trees, lawns, grass, plants or any other vegetation except from a three-gallon or smaller container. Vegetable gardens are exempt, as are greenhouse or nursery stocks and newly established lawns or sod less than five weeks old. Such sod must be watered only the minimum amount necessary to sustain it, and before 8 a.m. or after 6 p.m.

The use of water-cooled air conditioners without water-conserving equipment attached.

The taking of water fro fire hydrants except for fighting fires.

The operation of ornamental fountains.

The serving of water in restaurants except upon request.

The filling of swimming pools requiring more than five gallons. Pools may be filled to a level 2 feet below normal to protect the pool from hydrostatic damage if they were constructed or contracted for yesterday or earlier.

Citizens who feel they should be exempt from the restrictions can ask the city manager for a temporary exemption until an appeals committee designated by Council members can hear their cases.

The Alexandria regulations went into effect at 1:15 p.m. yesterday, but residents will be given only warnings until Wednesday. After that, the penalty for noncompliance can go as high as a $500 fine and suspension of water service.

The Council argued for more than two hours on word changes, ways to prevent the loss of jobs and whether to exclude shrubs and vegetable gardens before approving the measures by a 6-to-1 vote.

Council member Ellen Pickering voted against the ordinance because the restrictions begin and end at the discretion of the City Council rather than with an obsolute condition, such as a particular water level in the reservoir.

"I am in favor of water conservation," Pickering said after the meeting. "But there's room for suspicion that politics will come into play (in the timing of a decision to lift the restrictions.)

Meanwhile, Fairfax County police reported yesterday they received two complaints of people washing cars in violation of the water conservation ordinance. No one was charged in the incidents. A police spokesman said he did not know why the people were not charged, but it may have been that the complaints were unwarranted or the car washing could have been completed by the time police arrived.

Tanya Lansing, who was washing her red Chevette in front of her home at Westmoreland and Dillon Streets, said that although she lives in Fairfax County, her water does not come from the Occoquan reservoir, but from Falls Church. "They're not facing any shortage. I called to find out about it."

But less than a mile away, Judy Faith admired the manicured shrubs and flower gardens at her mother's home at 1755 Pimmit Dr., and said, "I guess God will take care of it."