The San Jose City Council last week enacted sweeping new water conservation rules in response to California’s drought. The new rules take effect immediately and will continue until March 31, 2016.

Q Am I affected?

A The rules apply to all 1 million residents of San Jose, as well as all businesses and industries, regardless of whether they receive their water from San Jose Water Co., the city’s municipal water department or Great Oaks Water Co.

Q What are the main changes?

A Think cars, pools and lawns. It is now prohibited for anyone in San Jose to wash a car with potable water at home, whether or not they are using a hose with a shut-off nozzle. Commercial car washes are still allowed, as long as the businesses use recirculating water. It is also now illegal to top off a residential swimming pool or hot tub any more than 1 foot. The only exception: pools or hot tubs that are drained to fix leaks. (It is still legal to buy a pool or hot tub, but it is illegal to fill them.) Also, it is prohibited to put in a new lawn between May 1 and Oct. 31 if it has a sprinkler system. In other words, you can install new grass only if you water it by hand, with drip irrigation or with recycled water. Planting drought-tolerant plants remains legal.

Q OK, but I have a lawn and it’s looking brown. When can I water it?

A Roughly 50 percent of the water consumed by urban residents in California is used to irrigate lawns and other outdoor landscaping. Under San Jose’s new rules, outdoor landscaping that requires sprinklers can only be watered two days a week, and only before 10 a.m. and after 8 p.m., when cooler temperatures reduce evaporation. Properties whose addresses end in odd numbers are allowed to water only on Mondays and Thursdays. Properties whose addresses end in even numbers may water only on Tuesdays and Fridays.

Q Are there exceptions?

A Yes. Anyone can water a lawn or other landscaping on any day with watering cans, with drip irrigation or by hand with a hose, as long as it has a shut-off nozzle. Residents must still only do it between 8 p.m. and 10 a.m. however. Public parks, playing fields, nurseries, day care centers, golf courses and schools also are restricted to watering outdoors during those hours. Only golf course greens can be watered.

Q Are there penalties?

A Yes. Under San Jose’s municipal code, violators can be fined $160 per offense.

Q How will the rules be enforced?

A Anyone seeing violations can call a hotline run by the Santa Clara Valley Water District, the county’s water wholesaler. The number to call is 408-630-2000. Or residents can email reports of water waste to drought@valleywater.org.

Q Will “water cops” be writing tickets?

A Not at first. When the water district receives word of violations, it will send out compliance officials to notify those responsible. After a second warning, the addresses of the offenders will be turned over to one of the three water retailers. The retailer can then refer future violations for possible fines to San Jose’s city code enforcement officers who normally enforce blight issues, illegal construction and other planning violations.

Q Why is the city cracking down?

A Two reasons. First, California is in the fourth year of the worst drought in the state’s history. The Sierra Nevada snowpack, a key source of water, is at 5 percent of its historic average. San Jose’s rainfall for the past four years has been barely half of normal, like many cities in the state. And reservoirs and water tables in many parts of California are at, or heading toward, dangerously low levels. Nobody knows how long the drought might continue. Australia recently had a drought that lasted 17 years, from 1995 to 2012. Second, Gov. Jerry Brown issued mandatory statewide water conservation rules April 1. San Jose’s three main water providers must cut water use 20 percent this summer compared with 2013 levels, or face fines of $10,000 a day.

Q Aren’t other rules already on the books?

A Yes. Under recent state drought rules, it already is illegal everywhere in California for restaurants to serve water unless diners request it. Also, hotels are required to notify guests that they can choose to not have towels and linens washed every day. It’s also prohibited statewide to water lawns so much that the water runs off onto sidewalks, streets or other properties. And it’s illegal to run sprinklers within 48 hours of measurable rain.

Q But don’t farmers use most of the water in California? Why do cities need to save?

A Farmers do use 80 percent of the water that people consume in California. But much of their water cannot be transferred easily to cities, either because they have legal rights to it, or because of infrastructure issues. Water that an almond grower in Modesto doesn’t pump from a well on his farm, for example, can’t be shipped to the Bay Area or Southern California. Many of the state’s farmers already have taken huge water cuts, losing 80 to 100 percent of their supplies from the Delta because of state and federal drought cutbacks. Most important, much of the water that urban areas save is from their own supplies. Groundwater or water in local reservoirs that San Jose residents don’t use this year can be saved if the drought drags on into next year or beyond.

Q Where can I get more information?

A Retail water providers will be notifying their customers in the weeks ahead. Also, the San Jose Environmental Services Department has more details at www.sjenvironment.org. Residents can also call 408-535-8550.

Paul Rogers covers resources and environmental issues. Contact him at 408-920-5045. Follow him at Twitter.com/PaulRogersSJMN