Each year, Sustainable San Mateo County works with a select group of Mills High School students to teach them about sustainability indicators. This year, the students researched Water, the 2015 Key Indicator. The Mills 2015 Indicators Projects add an important voice to the sustainability discussion and the complex subject of water.

[smc-box] • A Guide to Xeriscaping
Rain Barrels
Peninsula Groundwater Management and Water Supply
Microfiltration and Desalination
Conservation from Swimming Pools
Water Efficient Homes
Direct Potable Reuse
Aging Infrastructure Upgrades

A Guide to Xeriscaping

By: Camille Chan & Kayla Larot

What is Xeriscaping?

With the new constraints imposed by the California drought, you may be envisioning a bleak future for your garden: a wasteland of dry and dull. Fortunately, xeriscaping can rescue your “garden in distress!” Although “xeriscape” directly translates to “dry scape,” xeriscaping is a colorful, diversified, and exuberant style of landscaping. Fully devoted to water conservation, xeriscapes feature native plant life that thrive with little maintenance and minimal watering. Xeriscaping is the perfect opportunity to bring diverse native wildlife to your home.


Photo from Flickr user Carolannie…

What Can Xeriscapes Do for Our World?

Why invest in a xeriscape at all? The foremost reward for xeriscaping is water conservation. Catered to aid drought-ridden areas, xeriscaping can reduce a landscape’s water consumption by 50 to 75%. One of the most important advantages of xeriscaping is its contribution to the local environment. Xeriscaping is extremely eco-friendly as it reduces the amount of turf in a given territory. Less turf translates to less mowing, which significantly cuts down the amount of fossil fuels used to maintain vegetation survival, along with a reduction in fertilizers and pesticides. Lastly, xeriscapes strengthen native ecosystems, attracting local wildlife to thrive symbiotically with native plant life. Do not forget that you, the xeriscape owner, also benefit. Xeriscaped areas often have aesthetically unique appearances, which can increase the property value of residences. Even more, since xeriscapes require significantly less water and resources, you can sustain a healthy garden at a lower cost. Xeriscaping saves your money, your resources, and your time.

Photo from Flickr user Carolannie…

Let’s Xeriscape!

The art of xeriscaping relies on several principles to ensure that the ultimate goal of water conservation is achieved.

  • Design your xeriscape. Pay attention to areas that receive more shade or more sunlight. Recognize any obstacles in your setting that may impede landscaping or inhibit healthy plant growth. Look out for additional opportunities to reduce extensive water loss.
  • Keep your soil healthy! The ideal type of soil for xeriscapes is one that drains water effectively. Healthy soils can absorb at least a half inch of water per hour. Successful soil drainage allows plants to maximize water and nutrients that are available only within deeper soil layers.
  • Don’t let turf dominate. Maintaining large patches of turf is extremely costly when water is scarce.Therefore, minimize the proportion of turf area in your landscape, which is guaranteed to conserve a substantial amount of water.
  • Choose the right plants. Populate soiled areas with a large variety of native plants. Native plants thrive easily and almost independently when placed in familiar natural habitats. Key botanical characteristics that indicate drought resistance include stubby, glossy, leaves with small surface area. Remember that succulents are not the only drought-tolerant plants available! Explore the following mini descriptions of other plant species that are native to the Bay Area to add diversity to your landscape.
  • Nurture your mulch. Mulch is a compilation of organic material used to enrich and insulate soil. Covering your xeriscape with mulch seals moisture, maintains a stable soil temperature, and prevents weed invasion.
  • Evaluate your irrigation system. Soaker hoses are a great option. Unlike conventional garden hoses, soaker hoses release only as much water as can be absorbed by the soil at a given time. Keep in mind that xeriscape plants benefit more from occasional, deep watering sessions rather than frequent, light showers. Deep watering trains plant roots to grow deeper into the soil, giving access to cooler, moister layers of soil.

A Few Extra Tips for Happy Landscapers and Happy Xeriscapes…

  • Xeriscapes are not destined to be dry and monotone.To create a vibrant environment, plant several clusters of drought-tolerant perennials. These plants provide your garden with colorful, beautiful flowers and possess leaves that naturally maintain cooler temperatures for plant roots.
  • Organize your plant community by their varying water needs. Plants that require more water should be grouped together to prevent unnecessary water expenditures.
  • Avoid very large plants when establishing your xeriscape. Plants that are moderate or small in size prevent major water splurges.
  • Never feel pressured to cover the entire open area with vegetation. Maintaining a roomy environment promotes adequate gas exchange for your plant life, which ultimately reduces the risk of plant-ridden diseases.

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Rain Barrels

By: Jackie Chen

Do you know how much rain falls a year? How much of it is captured and reused? Why should you care? Well in Millbrae alone, 19 inches of rain fall on average very year. Only 0.10% is captured or recycled. That means that not only is water wasted, but your money is as well. Pollutants collected by rain can run into storm drains, damaging ocean and bay quality. Rain barrel installation is one way individuals can reduce environment damage from run-off and flooding, while saving personal and communal money.

On average, a 60 gallon barrel costs about $80-100 at typical stores like Home Depot. Installation is easy and the maintenance cost is minimal. Installing one 60 gallon rain barrel could save a household $4.37 per year if the barrels are emptied ten times. Rain barrels also reduce run off as the water kept in the barrel does not lead directly to sewers and thus takes some pressure off the county sewage cleaning systems. Rain barrels can replace wasteful hoses in when plants need to be watered or cars need to be washed. The Bay Area Water Safety and Conservation Agency (BAWSCA) is giving out rebates to people who install water barrels, as are certain water agencies. With rebates of up to $100, installing a 60-80 gallon water barrel could be free!

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Peninsula Groundwater Management and Water Supply

By: James Chen

As the drought in California grows worse by the day, groundwater management is becoming an increasingly important part of government’s response. According to a 2014 drought impact study performed by the University of California, Davis, the total statewide cost of the 2014 drought is $2.2 billion, with $1.5 billion of that quantity directly related to losses in agriculture. Based on measurements taken through the California Statewide Groundwater Elevation Monitoring Program, much of the agricultural sector has seen its water reserves and resources dwindle, extending the already existing losses.

In the San Francisco Bay Area, the Bay Area Water Supply & Conservation Agency, or BAWSCA, has affirmed that one of its statutory authorities is encouraging the use of recycled or reclaimed water in order to reduce groundwater usage and increase aquifer recharge. This objective, since its conception about two decades ago, has been produced through the agency’s participation in the Bay Area Regional Water Recycling Program, or BAWRP. The BAWRP Master Plan strongly emphasizes the ideal of sustainability and reliability in its analysis of the impact that increasing the use of recycled water would have. The large-scale implementation of recycled water aims to improve water supply reliability and quality for the San Francisco Bay and Delta, thus, advancing the long-term restoration of the Bay-Delta environment. In 2002, Daly City and San Francisco established a resolution to build a new water recycling plant providing irrigation to three major golf courses and also reverse the decline in Lake Merced’s water level, which reduced dependence on groundwater. Besides irrigating golf courses, the plant collects the water surplus during the winter for the summer season for purification, further replenishing the precious groundwater table.

More recently, the San Francisco Public Utilities Commission has taken wider-reaching action to store more groundwater for the benefit of up to almost three million Bay Area residents. In a KPIX report this past December, the SFPUC organized the Regional Groundwater Storage and Recovery Project to help store larger quantities of groundwater for dire emergencies caused by disasters or severe droughts. $113 million will place 16 facilities along the Peninsula to feed the needs relying on surface water, allowing the South Westside Groundwater Basin’s aquifer to collect precious rainwater. An additional seven million gallons of water would be pumped daily to Bay Area residents from the new well stations, pumps, and pipelines, amounting to savings equating the entire volume of the Crystal Springs Reservoir–around 20 million gallons. Following the commencement of construction in 2018, the region along the Peninsula and San Francisco can face less pressure in regards to the gradually lessening frequency of rainwater and Hetch Hetchy supply.

Following the governor’s signing of groundwater legislation described as “historic” in September of 2014, Senator Fran Pavley said, “California will no longer be the only Western state that does not manage its groundwater.” As a state, it has taken extensive natural devastation to finally invoke a change that has been desperately needed for years.

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Microfiltration and Desalination

By: Jenny Shen

With California’s current drought, it comes as little surprise that many are looking towards other ways of efficiently generating potable water. Two such processes under consideration are microfiltration and desalination. Considering the limited water that California has to begin with, these processes are ideal since microfiltration allows for water recycling while desalination utilizes the Pacific Ocean. As with any technology however, both microfiltration and desalination pose economic amongst environmental and/or political drawbacks.

Microfiltration, as defined by Thomas Muilenberg, consists of passing raw water through porous material often made of plastic. As its name indicates, the pores are “micro-sized.” At the Silicon Valley Advanced Water Purification Center (SVAWPC), microfiltration straws possess a pore size of 0.1 microns. These small pore sizes prove beneficial since they keep certain substances, including pathogens, from passing through the membrane. With little or no need for chemical treatment since the membrane filters out particles, maintenance of microfiltration systems is less taxing. The amount of chlorine usually added to water to reduce pathogens may also be lessened as well. Orange County’s water purification plant uses microfiltration, which aids in excluding small particle and bacteria from continuing on to further treatment.


From Pacific Institute’s “Desalination: With a Grain of Salt

Economically, microfiltration is relatively less costly especially in comparison to desalination, which often uses a high-energy process called reverse osmosis. The lower cost of microfiltration could partly be attributed to the higher water production frequency of microfiltration as compared to reverse osmosis. Orange County’s purification plant, for instance, produces double the amount of water that San Diego County’s desalination plant does”and for less than 33% of the desalination plant’s average cost. Additionally, with the help of microfiltration in recycling water, less energy”and consequently less money”is needed from importing water. Both microfiltration and reverse osmosis have a similar efficiency rate though; at SVAWPC, the efficiency rate was 85% for both processes.

Desalination takes advantage of California’s proximity to the ocean but requires extensive energy and money for functioning and can also threaten marine life. The Carlsbad Desalination Plant of San Diego County required $1 billion to build and provide 50 million gallons of drinking water from 100 million gallons of seawater. In the larger context though, the 50 million gallons of drinking water provides about 7% of the total water needed in SD County, which may cause some to question the viability of the desalination plant.

Desalination also often relies on reverse osmosis, which removes large macro chemicals, including salt, but uses up a lot of energy. As reported by Paul Rogers, the Carlsbad Plant will require “38 megawatts, enough to power 28,500 homes.” A report from the Pacific Institute states that water produced from desalination requires more energy than “any other water-supply or demand-management option in California.” In that frame energy prices, rather than other sources of water, will be more likely to influence the cost of desalinated water. The increased cost also impacts customers; for those using desalinated water from the Carlsbad Desalination Plant, they are expected to pay $5 or $7 more for their water bill.

Critics cite the harmful effects on marine environments in their arguments against supporting desalination plants. The Carlsbad Desalination Plant faced fourteen lawsuits and appeals by environmentalists until gaining the go-ahead in proceeding. Many critics of installing desalination plants, as mentioned by Bill DiBenedetto in “Largest Seawater Desalination Plant to Open Next Year,” refer to damming rivers, pumping groundwater, and conserving water as cheaper alternatives for obtaining clean water. For counties such as San Diego, though, they have very little water to conserve in the first place and may be extremely dependent on imported water. San Diego is completely reliant on Sierra snowmelt and the Colorado River for imported water. As water resources manager Bob Yamada stated, “With imported water supply, the control is not totally yours” whereas desalination and water recycling are locally controlled. So even in light of these disadvantages stemming from desalination plants, water agencies continue to consider their construction as an option. At least fifteen other desalination plants in addition to the Carlsbad Desalination Plant have been proposed along California’s coast.

With little available water, microfiltration proves useful in water recycling but in the long run, California may opt for desalination since the ocean provides a greater water source. However, in implementing desalination plants, officials should consider the effects on marine ecosystems and a potential increase in consumer and energy costs.

Conservation from Swimming Pools

By: Kaelan Tantuico

Sitting by the poolside on a hot summer day, ice-cold lemonade in hand, and book in the other, you may ask yourself, “How many cups of water like the one I hold did it take to fill this swimming pool?” The answer of course depends on the size of your pool.

A rough estimation of any pool’s water capacity can be taken by multiplying pool length * pool width * average depth, the result being the pool’s volume in cubic units.


Swimming pools can be filled in a variety of ways, depending on whether the pool is public or private.

Private pools can be filled from any number of sources; some use their own well, some fire departments will fill a well for a fee, you can source the water from the main water line, or you can even order water in bulk from a professional service provider.

Public pools must be “supplied with water by means of a permanently installed pipeline from a public water supply system holding a permit from the Department of Health Services or from another approved source.”

After their initial fill, the water level remains relatively constant, save for a few variables that inherently result in water loss, including evaporation, leakage, splashing, and backwashing.

Evaporation is the name we give to the process in which water changes from a liquid state to a gaseous state at the water’s surface. Evaporation is always occurring in any body of water and it is important to understand that what changes is the rate of evaporation.

The rate of evaporation is influenced by several factors including, but not limited to, surface area, temperature of the water, flow of air across the water’s surface, humidity, and even pressure.

Splashing is simply the tendency for water to exit the pool when it is in use by swimmers or when the pool overflows perhaps due to heavy rainfall or any other reason.

A pool leak is any place where the pool is losing water where it should not be and can be indicated by a greater drop in the water line than is regularly measured.

Pool leaks can occur anywhere in the closed water system that filters the pool as well as in any breaks in the lining of the pool. There are several ways to test if a leak is occurring, the most commonly used being the “bucket test.”

A backwash valve is used to reverse the flow of water going through the pool filter in order to clean it out, the water used in this process exits via the waste water line.

Managing Water Waste
There are several ways in which to manage water lost from these sources, all of which are straighforward.

  • Evaporation: The easiest way to cut down on water lost to evaporation is by installing pool covers that run the length of the pool. These covers blanket the pool and make the effects of humidity, wind, air temperature, and others, almost negligible as the cover provides a barrier from the water and the air at the surface.
  • Splashing: To cut down on water lost due to splashing, simply be more mindful of how much water you are splashing out of the pool when it is in use.
  • Leakage: The first step to managing water leakages is to frequently check the rate at which the water level in the pool is decreasing. If you notice that the water level is dropping much more rapidly than before or if it is generally decreasing at a quicker rate, perform the bucket test and check if your pool is leaking. Should you discover your pool is leaking, taking the proper steps to locate and patch the leak ensure that you are wasting no more water.
  • Backwashing: To cut down on backwash water usage, simply try and use as little water as you need to clean your pool filter.

How does pool water usage compare to water usage in other places?
In the grand scheme of water conservation, pools do not use as much water as we expect! Aside from the initial fill, pool water usage remains below that of lawns of the same square footage. Several recent data collections in L.A. County (where pools are much more common) have come about as a result of complaints on recent pool filling bans. While pools may require thousands more gallons to fill the first time, each year a pool uses 8,000 gallons less than a lawn of the same size.

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Water Efficient Homes

By: Michael Zshornack and Adam Wong

As a result of one of the most severe droughts in California’s history, water conservation is at the forefront of public thought. From the statewide level down to individual households, all must do their part in reducing water usage lest we run out of this invaluable resource. Continuing innovation and development of water-saving household appliances expedite the process, such as showerheads and water-saving toilets. In this report, we will investigate the feasibility of conserving water on a house-by-house basis within the San Mateo County.

Current Water Trends

Currently, San Mateo County uses approximately 81.78 million gallons of water per day out of a total supply assurance of 90.96 million gallons per day. Due to the limited amount of water available from the Hetch Hetchy water system, that supply assurance is not expected to grow despite increasing demand of water from a growing population. In an interview with Shelly Reider, the Environmental Programs Manager of the City of Millbrae, finding and implementing alternatives sources of water (such as desalination) would be far too expensive. We therefore must look to simple conservation to cut back on water usage, as it is the cheapest and most efficient method, especially within the household. According to the Bay Area Water Supply & Conservation Agency (BAWSCA), approximately 69% of all water used in the San Mateo County from 2012 to 2013 was consumed by households. A majority of this can be attributed to outdoor landscaping, which can occupy over 50% of total water use. As a result, there is a need for more water efficient households, both inside and outside the home.

Current Technologies

There are numerous household appliances that are readily available for consumers to purchase and install on their own. From high-efficiency toilets and washers to faucet heads and shower heads, these are simple but effective methods to reduce water usage inside the home. In addition, organizations such as BAWSCA offer rebate programs to replace old and aging technologies with water efficient appliances, making it more economically feasible to upgrade the house. Conserving water outside the home is just as feasible as inside the home. Native, drought-resistant plants can be planted in favor of water-hungry lawn grass (known as xeriscaping), and any landscaping can be done using grey water (reusable wastewater from residential, commercial and industrial bathroom sinks, bath tub shower drains, and clothes washing equipment drains).

Emerging Technologies

Multiple new technologies aimed towards the typical household also seek to promote conservation in innovative ways. One of the largest rising methods is the development of entirely self sustainable homes. In February of 2014, KB Home, a homebuilding company, unveiled its “Double ZeroHouse” which boasts extreme water and energy efficiency. The home is designed to be able to recycle water that flows down the drains, and reuse that water for landscaping. The home also has the ability to extract energy from greywater and use it to preheat water in the water heater which reduces heating costs. Water recycling technology is even active in the house’s appliances as the dishwasher uses 33% less water than other high-efficiency dishwashers. However, this house has only seen much use in the city of Lancaster, CA. Though an expensive technology, the city of Lancaster has firmly invested in this venture, aiming to become one of the most energy and water efficient cities of the modern day. They have set the model for cities that wish to progress towards energy efficiency. Moving towards the future, we can only hope to see more cities follow suit, enacting the necessary legislation towards achieving this technology.

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Direct Potable Reuse

By: Monica Lee

Direct Potable Reuse, also known as recycled water, is becoming a viable water conservation method in many drought ridden states. DPR is purified water that is introduced directly into a potable water supply distribution system or into the raw water supply immediately upstream of a water treatment plant. In other words, it is sewage water that is treated and purified allowing it to be used for various purposes such as irrigation, indoor plumbing, and drinking. Many cities have begun pursuing DPR as a means of fighting the drought. Big Springs and Wichita Falls in Texas have been using DPR since May 2013 and June 2014 respectively. Cloudcroft, New Mexico is currently constructing a DPR facility due for completion in 2015, according to the New Mexico State Environment Department. California, however, has confined itself to Indirect Potable Reuse facilities only. Unlike direct potable reuse, IPR reclaims water and then returns it to a lake or river before filtering it through a drinking treatment plant. Oftentimes, returning reclaimed water to these bodies of water can prove counter-effective. As it enters its fourth year in a drought, Direct Potable Reuse may need to be considered as a drought solution in the state. Using Big Springs as a case study, we may be able to objectively analyze the benefits, costs, and effectiveness of Direct Potable Reuse.

Big Springs makes use of multiple high-tech treatment processes to clean water. Wastewater is pretreated before entering into the Raw Water Production Facility, the city’s DPR facility. In the facility, wastewater is removed of particles and inorganic molecules through membrane ultrafiltration and reverse osmosis. During an advance oxidation process, UV light and hydrogen peroxide oxidize remaining organic matter and pathogens. The water pumped out of the facility is also mixed with raw water (water coming from natural resources) in a lake and pumped to five drinking water facilities where it is treated again to ensure potation. In the end, only twenty percent of the water pumped into residents’ kitchen faucets and bathtubs is treated wastewater.

What makes California’s Indirect Potable Reuse different is that treated water is pumped into a natural water source where it must sit for six months. The natural source acts as an “environmental barrier” to appease the public, who remains wary of possible side effects DPR could have on health. Unfortunately, even though it soothes public qualms, mixing reclaimed water with reservoir water actually makes it dirtier than it began. A large amount of energy and money is wasted re-filtering and re-cleaning the water. Big Springs had to combat public fears and the “yuck factor” of recycled water within their community as well, but the severity of the drought and proper education convinced residents of DPR’s necessity and value. Concerning public education techniques, John Grant, the general manager for the Colorado River Municipal Water District (CRMWD) who helped build the DPR facility in Big Springs, said, “We held public meetings, we did news releases, we did television and radio, and we went around to civic clubs and did talks.” Gaining public support ended up easier than expected as a result.

Now that a DPR facility is already operational, establishing recycled water facilities in California should be much easier. Of course, factors such as cost should be considered. Currently, the Big Springs plant costs about $14 million and serves about 250,000 people, about a fourth of San Francisco’s population size. Implementing facilities large enough to support the city, much less the Bay Area (which has a population size of about 7 million), will be more costly and challenging. However, because many cities have already established IPR facilities, transitioning to a DPR facility would not be as costly as building a plant from scratch. San Jose, which already has the largest advanced wastewater treatment facility in the western United States, cleans about 110 million gallons of wastewater a day. If this single facility were able to transition into a DPR plant, about 1.4 million people would benefit. Also, DPR, although costly, proves to be one of the cheaper solutions to water conservation. According to David Smith, the Managing Director of WateReuse California, “Because of additional treatment and energy consumption associated with importing water and the challenges proposed by IPR in some communities, DPR is expected to cost less than other forms of recycling in many cases.” Given that only one treatment plant is required instead of two (one to clean before the environmental barrier, one to clean after), DPR should cost much less than IPR. In fact, a model from the Miami Dade County provides estimates that DPR could be more than $4 million cheaper in that county.

In our fourth year in the drought, direct potable reuse can no longer be simply be a possibility. As both a safe and functional method of cleaning water, it must be considered as a part of California’s water system and as a viable conservation method.

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Aging Infrastructure Upgrades

By: Peter Schafhalter

While California currently faces one of the most severe droughts on record, most of the discussion regarding our limited water supply has been focused on consumer conservation and finding new water sources. However, these alternatives overlook a decade-old problem of senseless water waste caused by our very water supply system: the problems in our aging infrastructure.

San Mateo County’s water is mostly supplied by the Hetch Hetchy Water System via the San Francisco Public Utilities Commission. 85% of the water originates from snowmelt in the Sierra Nevada. The snowmelt is stored in Hetch Hetchy Reservoir from which it travels over 250 kilometers to the Bay Area relying mostly on a gravity-based system and an aqueduct for transportation. The other 15% comes from runoff in the Peninsula and Alameda watersheds. Currently, the system supplies water to almost 3 million people in the Bay Area.

In 1913, the Raker Act permitted construction of the Hetch Hetchy Water System on federal lands. By 1934, Hetch Hetchy began delivering water to San Francisco. Unfortunately, the current infrastructure is outdated and in need of improvements. Construction began over a century ago, and the aged system has been put under stress from natural disaster including the 1989 earthquake and the drought of the 1990s. According to a study by the American Society of Civil Engineers, Bay Area water infrastructure needs $20 million dollars per year in funding for improvements to water infrastructure; however, this faces political opposition because this would increase consumer water rates.

Some has been done to modernize the system: in 2002, voters passed a $4.6 billion dollar measure to upgrade the local Bay Area water supply system connecting to Hetch Hetchy. The upgrade renovates ancient pipes, increases reservoir storage capacity, and creates more redundancy in the system in order protect against a potential future earthquake. Furthermore, the upgrade increases the efficiency of water use through better delivery of recycled water and groundwater.

However, local improvements do not help much in the greater context of California’s drought. Serious water leakage generally occurs in large pipes where the water pressure is much higher. The EPA estimates that public water systems lose around 1/6 of their water, mostly due to leaks. Estimates indicate that California could feasibly save 113 billion gallons of water per year simply by reducing leakage. Much of the water is lost after it has been treated”between the water main and the consumer. This means that in addition to water, expensive energy used to treat the water is also wasted, and creates a much higher price tag associated with water loss. The large amount of water saved would allow California to save millions otherwise spent on water treatment and costly expansions of water sources.

In the discussion of managing California’s drought, renovating ancient California’s water supply system is a logical long-term solution. While costly, the rewards seem bountiful, and state-of-the-art improvements to its pre-Second World War infrastructure are long overdue.

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