Water Recycling: Making the Most of Every Drop
We’ve long recycled aluminum, plastic, glass, and newspaper. But what about water? The economic and environmental benefits are surprising.
One of the chief concerns on every Californian’s mind right now is water: How can we make the most of this precious natural resource? It’s crucial that freshwater reserves are managed appropriately, but it’s just as critical to maximize the reward of those supplies that have already been used. Recycling water is all about efficiency — making sure gallons that might otherwise go to waste are instead cleaned, treated, and used again through innovative technologies. If California is to satisfy its future water needs, reclaiming and reusing this increasingly scarce treasure is imperative.
Mother Nature’s Model
Recycling water is nothing new. Nature has been recycling the earth’s water since the beginning of time. Through a never-ending cycle, drops of water fall from the sky as rain, snow, sleet and hail. This water either flows down to the sea via streams and rivers or it soaks directly into the soil. Roots of plants and trees take their share. Another portion of the precipitation percolates slowly down through pores and crevices in underlying bedrock to recharge vast aquifers, those groundwater reservoirs that lie deep beneath the surface. These aquifers may store the water for centuries, even thousands of years, until natural springs or some manmade activity — these days it’s most likely to be a powerful well pump — brings the water up again to repeat the cycle.
Meanwhile, the sun is relentlessly reclaiming surface moisture through evaporation. The evaporated moisture becomes lighter-than-air water vapor, rising into the atmosphere until it is transformed into those wonderfully varied wisps and puffs of condensed droplets we know as clouds. When the burden of moisture becomes more than the clouds can bear, they drop the water back to ground or sea. In this closed-loop journey no water is ever really lost and no new water is added; it just assumes different forms in different locations over and over.
Often the water picks up impurities along the way — dust, smoke, salt, sulfur, arsenic, acids, assorted organic chemicals and bacteria. Fortunately, over many, many years and cycles, natural filtration through topsoil to the sand, clay, gravel and bedrock below separates out most of the impurities. Wetlands and aquifers, for example, are among the most important natural filtering systems we have for purifying water, but to perform at their best they need to be left undisturbed and given plenty of time to do their work.
Changing Incentives
As long as there was a supply of clean, fresh water, Californians had little incentive to explore methods of recycling water. But several decades ago the picture changed dramatically. The 1970s brought us the federal Clean Water Act, the Safe Drinking Water Act, the Endangered Species Act, and in California a severe drought took its toll. Our population swelled beyond our water infrastructure’s ability to provide for everyone. California also grew exponentially as an agricultural and manufacturing powerhouse, with water being a key ingredient.
Today, California is among the major players worldwide in water recycling. There are over 250 water recycling plants currently operating, with more planned for the future. The State Legislature has set a goal for California to recycle over one million acre-feet of water annually, enough to meet the needs of the 17 million additional residents California is projected to have by 2030.
Recycled water is defined as wastewater treated to a specified quality in order to be used again for a specified purpose. Until recently, California’s water agencies focused on processing wastewater mainly for irrigation and landscaping. Only a small share — about 14 percent — was further purified for more advanced uses such as groundwater recharge.
Orange County’s Bright Example
A dramatic example of water recycling is Orange County Water District’s Groundwater Replenishment System in Fountain Valley. Right now, it’s the largest water recycling and purification project of its kind anywhere. The system owes its origins to a water crisis that took place in 1965, when local officials found that the groundwater level had fallen so low that salt water from the Pacific was seeping into their underground aquifer.
To prevent this, the district began a pilot project known as Water Factory 21. First, wastewater was put through a stringent, multi-step treatment process that brought it up to drinking water standards. Next, it was injected into a series of wells that were drilled along the coast to create a barrier to the sea. This barrier worked, protecting hundreds of threatened freshwater wells as far inland as 10 miles. After lying underground for a period of months, the treated water percolated back into the local deepwater aquifer to recharge the municipal water supply. Water Factory 21 garnered all sorts of international awards for innovation and it proved that advanced water recycling could greatly benefit large municipalities. Today’s system provides enough drinkingquality water to supply 500,000 Orange County residents annually. It uses an innovative three-stage process that involves microfiltration, reverse osmosis, and an ultraviolet light and hydrogen peroxide treatment to deactivate any remaining organic compounds.
Once the purification process is completed, half the potable water is injected into Orange County’s underground pressure ridge to recharge the seawater barrier. The remaining drinking water is piped to lakes in Anaheim where it takes the natural path of rainwater, filtering through sand and gravel to the deep aquifers below. As if these are not benefits enough, the system also reduces the amount of waste and storm water lost in discharge to the ocean. Furthermore, the process uses an estimated 50 percent less energy than it takes to transport water imported from the north and the Colorado River.