SEATTLE — It’s one of the great American summer pastimes: Pulling the car onto the driveway on a sun-drenched Saturday afternoon, lathering it up with soap, rinsing it off and watching the sudsy water flow toward the storm drain.

Now, officials in Washington and elsewhere are telling residents to either take that old ride to the car wash, or hold the soap and wash the car over gravel or grass to filter the dirty water.

The officials are trying to prevent the runoff, with all of its soap, grim and metals from the car, from reaching rivers and streams and harming the fish and other aquatic life in them.

“The soaps are just as toxic as some of the chemicals we regulate in the industrial (sector). They kill fish,” said Sandy Howard, a Washington Department of Ecology spokeswoman.

The state, however, isn’t banning car washing. Instead, it is requiring cities to adopt ordinances that prohibit anything other than clean storm water from entering drains as part of a broader storm-water permit it issues.

While there are no federal regulations dealing specifically with residential car washing and storm-water pollution, local governments may prohibit car wash water if it’s a significant part of the storm-water problem.

The Environmental Protection Agency, along with numerous cities and states, are however urging residents to keep soapy wash water out of storm drains and have launched public education campaigns for more fish-friendly car washing.

Some eco-friendly West Coast cities, such as Santa Monica, Calif., have taken it a step further, fining residents $500 if runoff leaves their property. A few fines have been issued.

The town of Fairfax, north of San Francisco, briefly considered banning residential car washing but many residents rebelled.

“While we were at it, we decided not to kill Mom and apple pie,” said David Weinsoff, Fairfax’s mayor. “There are certain things in our community we assume that we can do. People wash their cars. They have hot dogs on July 4th.”

The city of Vancouver, Wash., is rewriting its ordinance to omit car wash water as an allowable storm-water discharge to comply with state rules. But the city won’t be issuing tickets, public works director Brian Carlson said.

In Washington, state and local officials say they’re not going to bust scofflaws either.

“Are we going to have car wash police out there? No,” said Doug Navetski, with the water quality division of King County. “We’ll do public education.”

As part of their campaign, officials suggest that residents can wash their cars on gravel or grass to filter the suds, grime and metals. Better yet, they say, take it to a commercial car wash, which treats runoff.

Even washing a car without soap or with biodegradable soap is a no-no if the water runs off into storm drains, because it still picks up oil, grease and metals from the vehicle’s brake pads.

Storm water is the one of the biggest threat to rivers and streams in urban areas, state officials say. When it rains, tiny sources of pollution — drops of oil or antifreeze, copper shavings from car brakes and pet waste — gets swept up and washed into the rivers and streams.

Soaps in particular dissolve the protective mucous layer on fish and natural oils in the gills, making fish more susceptible to diseases.

“Individual actions are not only part of the problem but really the biggest problem,” said Chris Wilke, pollution prevention director with Puget Soundkeeper Alliance.

Shane Coakley, who owns a real estate investment firm in Federal Way, washes his truck in his driveway but takes his Bentley convertible to a commercial car wash twice a week. He said he’d reconsider washing both vehicles at a car wash if it means keeping local waters clean.

“If everybody does their little part, it adds up,” he said.