SAN FRANCISCO, Calif. — Existing technologies and practices can help California businesses save up to 1.3 million acre-feet of water every year -- that’s enough to meet the needs of Los Angeles, San Diego and San Francisco, according to a new research.

The Natural Resources Defense Council published a comprehensive report this week about the array of water-saving opportunities available for the commercial, industrial and institutional sector (CII) in the nation’s most populous state.

The release of "Making Every Drop Work: Increasing Water Efficiency in California's Commercial, Industrial, and Institutional (CII) Sector" comes at a time when water issues are drawing increasingly more attention with California facing its third consecutive drought year. At the same time, it's working to meet a statewide goal of reducing per capita water use 20 percent by 2020.

Although based on the water-saving potential in California, the report's recommendations are in many ways universal and the technologies can be applied to other regions.

The report estimate's California's CII sector is responsible for about a third of urban water use, but technologies such as high-efficiency toilets and fixtures, water meters and sensors, and on-site treatment can cut consumption by as much as 50 percent.

Water-saving opportunities include:

• Landscaping: Nearly 1 million acre-feet of water is used for the landscapes of schools, offices, street medians and parks, about 70 percent of which is destined for thirsty turf. Smart irrigation controllers and moisture sensors can halve water consumption and are subject to many rebates and financial incentives throughout the state to offset the investment expense.

Note: The annual water needs of two families of four can be met with 1 acre-foot of water, according to NRDC.

• Cooling: Cooling towers can account for up to half of a building’s water use, largely due to water evaporation during the cooling cycle. Installing a conductivity meter and controller can cost less than $1,500, but can save a business up to $4,000 per year. Rebates may be offered.

• Taps: Up to 590 gallons of water may be used in a mid-sized commercial kitchen daily. Installing a low-flow faucet aerator can cut use by as much as 50 percent without sacrificing performance, while also reducing the cost of heating the faucet water by up to 50 percent. Aerators cost $5.

• Shower heads: Efficient shower heads can be bought in bulk for as little as $5 each for use in hotels, hospitals, gyms and dorms; the payback is typically less than two years. A low-flow shower head can save 10 gallons for every 5-minute shower -- that translates to $3,600 in average annual savings if 100 people shower daily and sewer costs about 1 cent per gallon.

• Toilets: 15 percent of water use in the CII sector takes place in bathrooms, mostly from toilets. There are about 2.4 million inefficient toilets that use up to 5 gallons of water per flush still in operation. Replacing an old one with a new 1.3-gallon per flush toilet -- which will be required by the state in 2014 -- can save up to 19,000 gallons of water per year. The payback period ranges from 1 to 3 years; many rebates offered.

But while these tools are readily available, there are many barriers to their widespread deployment: lack of business investment capital, insufficient funding for rebate programs, low water costs, and the need for more data and trained staff at water agencies, among other challenges.

Oil refining, the report found, is the industry with the highest water savings potential in the industrial sector, capable of saving as much as 78,000 acre-feet of water annually by adopting energy efficiency technologies and practices.

Large cooling towers at Chevron's Richmond refinery minimize fresh water use. Source: Chevron

Despite the challenges, there are many businesses that have taken great strides in reducing their water use. Chevron, for example, installed a water recycling system that will enable the  refinery to use 8 million gallons of recycled wastewater daily; the facility uses on average 10-12 million gallons every day.

Intel has invested $100 million a year since 1995 on water use efficiency, saving enough water to supply 180,000 homes for a year. One of its initiatives involves an Arizona campus with processing equipment that was designed to use 75 percent less water than the industry average: 2.5 million gallons per day, rather than 8 million.