The biggest sip of the straw from the Bay Area's water supply comes from people living in just three water districts: They consume nearly three to four times the amount of water as residents in 23 other municipalities and districts, according to data from the Bay Area Water Supply and Conservation Agency, whose member agencies receive most of their potable water from the Hetch Hetchy system.
Residential use per capita is highest in the wealthiest communities while residents in the least financially advantaged communities consumed the least, according to the 2019-2020 annual survey, the latest to be published.
The differences are striking amid the growing drought, and there are currently no mandatory water restrictions to curtail use.
The biggest water users are in the Purissima Hills Water District, which serves two-thirds of Los Altos Hills and an unincorporated area to the south. Residents there used 248.9 gallons of water per capita per day in fiscal year 2019-2020, according to the water agency's data.
Second in line are Hillsborough residents, who use 215.8 gallons per capita per day.
Residents of California Water Service's Bear Gulch District, which serves Atherton, Woodside, Portola Valley and parts of Menlo Park, use 153.1 gallons per capita per day.
Per capita, residents in the 26 Bay Area Water Supply and Conservation Agency (BAWSCA) member agencies use 63.4 gallons on average per day. Fifteen communities use less than that amount, with East Palo Alto residents using the least, at 38.1 gallons per capita per day.
Frugality isn't at the heart of this stark contrast — it's real estate, some water operators said. In an urban environment or a community with few parks and higher-density housing, water use is pretty much confined to drinking, cleaning and bathing. But in communities with lush lawns, expansive acreage and landscaping, water use skyrockets.
That's the case in Hillsborough and Los Altos Hills, where there are primarily estate homes with most having a minimum lot size of one-half to 1 acre. Water demand for landscaping, pools and ponds is sizable. In its 2012 voluntary landscaping guidelines for Los Altos Hills, Purissima Hills Water District noted that landscaping accounted for 75% of water usage.
In Hillsborough, more than two-thirds of all water is used for irrigation, pools and other outdoor purposes, according to the town's website. Water conservation efforts have traditionally focused on indoor water use such as water-efficient toilets, shower heads and washing machines, the website stated.
However, "reducing outdoor water use represents the greatest opportunity for Hillsborough to conserve water. The town has implemented several new programs to promote outdoor water conservation," the town website stated.
Considering its potential water savings, the 2020 Urban Water Management Plan for California Water Service's Bear Gulch District found that limiting landscape irrigation to one to three days per week, prohibiting irrigating ornamental turf on public street medians with potable water and banning filling ornamental lakes and ponds among other restrictions could reduce a projected water-shortage gap by 26%.
Closer to home, three Peninsula cities also rank in the upper echelons of water use, according to BAWSCA: Palo Alto, Menlo Park and Mountain View. Below are snapshots of their water usage.
Most Palo Altans might not have the large lots of Hillsborough and Los Altos Hills, but the city's residents rank as the fourth thirstiest in the BAWSCA system, at 90 gallons per capita per day.
The city's 2020 Urban Water Management Plan and Water Shortage Contingency Plan, published in June, found that 63% of water was for residential use.
Most of that went to landscaping, said Catherine Elvert, city of Palo Alto Utilities communications manager.
"Landscaping in residential areas for homes constitutes 50% or more of a home's total water use. The approximate 50% of water use per household is an average estimate of water use for a single-family home. This of course will vary based on landscape area and plant type," Elvert said.
Business and industry used 18% of water; irrigation customers used 12%; and public and city facilities consumed 7%, according to the water management plan.
The city uses some recycled water from its Regional Water Quality Control Plant, including 36 acre feet that went to parks in fiscal year 2020; 316 acre feet used at the municipal golf course; and 25 acre feet for the duck pond. Fountains at Lytton Plaza and California Avenue also use recirculating water, said city spokesperson Jeanne Billeci.
At the beginning of the current drought, the city began to reduce potable water use in grass areas that were not playing fields, but it has kept watering areas with trees, Billeci said. The city converted some turf areas into native plant landscapes and uses recycled water from the Regional Water Quality Control Plant at Greer Park, she added.
Menlo Park Municipal Water residential customers used 67.2 gallons of water per capita per day in fiscal year 2019-2020, according to BAWSCA, ranking it the seventh largest water user among member agencies. Menlo Park Utilities Department didn't have specifics regarding how its water is used by residents, as they normally have just one meter measuring water for both indoor and outdoor use, the department stated in an email. The same goes for smaller non-residential customers. Larger non-residential customers normally have separate meters for indoor and outdoor use.
According to the city's 2020 Urban Water Management Plan, 41% of water use was residential from 2016-2020. Commercial, industrial and institutional use, large sectors in the city, used 44% during the same time period. Irrigation represented 12% of total water demand.
Overall, water users, both residential and commercial, use about 1.26 million gallons per day. The number pertains to water use within the district's boundaries only, however, and doesn't include uses by customers in the California Water Service area, which also serves some Menlo Park customers.
In 2020, the city used approximately 70,500 million gallons per day for its parks and landscaping, which excluded any use of water in the California Water Service areas.
The city's parks maintenance team has been conserving water by using mulch, setting mower blades to three inches to encourage deep roots, using drought-tolerant and resistant plants and trees, repairing irrigation leaks as soon as they are discovered and adjusting sprinkler heads to prevent runoff, adding drip systems and smart irrigation controllers, according to the utilities department.
Mountain View residents used 62.4 gallons of water per capita per day, ranking the city the 11th thirstiest, but its usage is below the average per capita residential use among the BAWSCA member agencies, according to the water agency.
The city's largest category of water users is residential, followed by large landscape and commercial or institutional uses, city Water Resources Manager Elizabeth Flegel said. In 2020, 58% was for residential use; 24% for large landscape irrigation; 11% for commercial and institutional use; 3% was for industrial use; and 0.08% for construction. Recycled water amounted to 3.7%, according to the city's 2020 recently adopted 2020 Urban Water Management Plan.
For its municipal water use, the city has nearly 200 water meters serving city-owned properties, including parks and landscaping. Usage varies over time, but typically accounts for 2% to 3% of total citywide water use, Flegel said.
Although Mountain View has overall seen a steady increase in water usage since 2017, its current water demand is 16% below the 2013 pre-drought baseline, according to the water management plan.
When pushed by a drought, customers respond to conservation efforts, Flegel said. The city's historical water demand shows a general downward trend in water use since the mid-1980s, according to its urban water management plan. In periods of drought, the city had rapid drops in water use. Landscaping water use dropped by nearly a third in 2015 and 2016 during the drought, according to the management plan, with single-family residential use also dropping significantly. Commercial, industrial and institutional use dropped and stayed steady starting in 2015 and in 2020 it is the only sector that dropped.
Mountain View encourages customers to use water wisely and limit irrigation to three days per week, Flegel said.
"The city's Parks Division carefully manages landscape irrigation to maintain efficiency and is following the same voluntary conservation measures currently requested from our customers," she said.
The evolving city of East Palo Alto tops BAWSCA's list of the water conservers at 38.1 gallons per capita per day in fiscal year 2019-2020. Water use has gone down overall since 2010, even as its population and commercial development have grown, from a high of 88 gallons per capita per day in 2010 when the service population for the city-owned utility was 22,916 to 60 gallons per capita per day in 2020 with a service population of 25,935, according to the city's 2020 Urban Water Management Plan and Water Shortage Contingency Plan, which was published in June. Some East Palo Alto residents are also served by a water cooperative and a mutual water company, which are not figured into this data.
Although the city doesn't break out its residential use by indoor and outdoor uses, it estimated residential water use as higher than BAWSCA's 2019-2020 measurement. In 2020, residents used 38 gallons per capita per day for indoor use and four gallons per capita per day outdoors.
The city estimates 71% of its water is used in residences. Commercial users consume 18%, while institutional and government uses 1% and industrial uses 1%; 8% of its water is lost through leaks and for unknown reasons.
Patrick Heisinger, assistant city manager, said that in part the city's low water use is due to half of its residences being multifamily units.
"There's not big open space watering and you don't see a lot of big gardens; there's not big, endless landscapes like in Hillsborough," he said.
Although the city is planning multiple large-scale commercial projects, those buildings would have all-new infrastructure that would save "a ton" of water, he said. The city is also looking at other ways to chip away at water use in its five parks and at school district playing fields. The city is in discussions with the Ravenswood City School District to potentially resurface its playing fields with synthetic turf, he said.
While none of the cities has implemented mandatory restrictions on water usage, they do offer multiple incentives and rebates.
Mountain View offers free water-wise surveys, free trees to help cool the community and rebates for landscaping and other water-conserving methods. Visit mountainview.gov.
Menlo Park offers free rain barrels, landscaping rebates, smart sprinkler-control rebates, free fixtures and, for commercial and multifamily residential consumers, a free landscape analysis program. Visit menlopark.org.
Palo Alto offers rain barrel, cistern and pervious-pavement rebates as well as rebates for water-wide landscaping. The city is considering instituting an online water-monitoring program to help residents view and regulate their water use. Visit cityofpaloalto.org.