Orange County’s Drought-Resilient Water Supply
The Other California Innovation That Went Global
When most people think about technology being exported from California, we think about Silicon Valley – Google, Apple, and Facebook. But it’s a rather non-descript group of buildings in Orange County that are attracting world attention. A steady stream of scientists, engineers, and politicians from drought-stricken places like Australia and Israel visit regularly to learn what is going on within these concrete walls. What attracts them? A new, clean source of water that can quench the thirst of growing populations, even during drought.
Necessity: the Mother of Invention
In the 1970s, Orange County had a serious problem with their water supply. Water from the beautiful Pacific that we all love so much was seeping into the groundwater we drink and use every day. The solution that the Orange County Water District engineered set them up for creating a drought-resilient water supply that is helping us cope with less rainfall.
Mehul Patel is one of the engineers at the Orange County Water District (OCWD) in charge of protecting Orange County’s groundwater basin from seawater intrusion, and he outlines the problem quite simply: “To prevent seawater from entering the aquifer, fresh water is injected underground 24 hours a day to act as a ‘wall’ between the Pacific and our groundwater. In the 1970s, the water used for injection was largely imported from Northern California or the Colorado River. Unfortunately, it was becoming more expensive and less reliable.”
To solve the problem, engineers at OCWD found a way to purify used water (or wastewater) and inject it into the barrier, so that the more expensive imported water could be reserved for drinking water supplies. The plant that created this water source was called Water Factory 21.
However, as Orange County became what it is today, more and more water was needed to serve the population, especially during California’s cyclical droughts. At that time Mehul Patel, now in charge of the Groundwater Replenishment System, was an intern with OCWD. He says that OCWD’s demand was fast outstripping supply, “We could only pump up to 15 million gallons a day from Water Factory 21 into the region’s underground aquifer to prevent seawater intrusion, but we needed 30 million gallons to meet the demands of the seawater intrusion barrier due to more families moving into the area.”
At the same time, the Orange County Sanitation District had a problem: as farmland turned into housing divisions, the pipes needed to prevent flooding during rain storms were no longer large enough.
At this point, the leaders of both districts had a choice – they could ask taxpayers and ratepayers to fund two separate projects to solve the problems, or they could work together to make money go farther. They chose Option 2. Says Patel: “OCWD leaders supported the Groundwater Replenishment System because it provided reliable, high quality water at a reasonable price.”
From that decision came one of California’s best-unsung innovations that has made its way across the globe, especially to places where water is in short supply because of drought. OCWD takes the Sanitation District’s treated used water and puts it through a three step process that purifies it into some of the cleanest water you’ll find. After the water is purified, it is pumped back in the groundwater basin for later use.
Option Two: Purify Used Water to Near Distilled Quality
Water is one of the oldest substances on earth. It has been used and reused more times that we can imagine or count. The water found in your morning cup of coffee could have been in the body of a T-Rex or a wooly mammoth – or drunk by someone in Paris a few years ago. Recycled water is the way of the world, and OCWD’s Groundwater Replenishment System simply speeds up the process. Says Patel, “Our three step process purifies the water so well that we have to add minerals back into it.”
Step 1: Microfiltration
Pre-treated wastewater is put through pipes filled with fine white straws with holes 300 times smaller than a human hair. Walking through the plant sounds a bit like being surrounded by giant washing machines – except they are actually washing water.
Step 2: Reverse Osmosis
Reverse osmosis is the second step in which water is pushed through membranes 1,000 times smaller than a human hair. These membranes filter out bacteria, viruses, pharmaceuticals and anything that managed to make it through microfiltration.
Step 3: UV with H202
As an extra layer of protection, water is exposed to high-intensity ultraviolet (UV) light with hydrogen peroxide (H2O2) to disinfect and to destroy any trace organic compounds that may have passed through the reverse osmosis membranes. The UV light is similar to the lights used in tanning beds.
The result of this process is water that is so pure, minerals must be added back into it. Sure, it’s clean – but how does it taste before minerals are added? You can try a glass at the end of a tour of the GRWS plant and it’s flat – like nothing at all. It tastes like water!
The purified water is then pumped back underground to protect the aquifer from seawater intrusion and to serve the needs of the surrounding community. OCWD is currently expanding the GRWS plant to ensure a reliable water supply for Orange County, even through natural disasters like drought.
Advanced Water Purification Goes Global
OCWD’s Groundwater Replenishment System and Mehul Patel receive visitors from around the world who want to build similar plants in their own communities. When asked if OCWD’s was the first plant, he says no – “Singapore and Brisbane, Australia were the first two groups to catch on to this solution. They worked with us and used the technology we were developing to build their plants before ours was completed.” He explains that each city was experiencing a water shortage so severe, they had to act extremely fast.
Singapore’s issue was similar to Orange County’s in that their population was booming and it was difficult to keep up with new demand. It rains quite a bit in Singapore. Unfortunately, they have no way to capture that water. They sent engineers and scientists to Orange County throughout the 1990s and implemented the system OCWD created before the Groundwater Replenishment System was built.
Brisbane had the opposite problem. It simply stopped raining in Queensland, Australia – the drought was so bad and prolonged, it severely dried up the great Murray River (Australia’s answer to America’s Mississippi). Patel notes that “reservoirs were running dangerously low, so the Queensland Government adopted our system, believing that if it was good enough to satisfy California’s strict rules for water quality, it would work for them.” They built four different plants within three to four years.
Today, Patel says that many groups come from the Middle East and from Asia, as well as from industrial interests like computer chip manufacturers and dye makers, who want to figure out how to make their water budget go farther.
A steady supply of clean water is a basic requirement for a healthy economy and a healthy population. As water budgets shrink, populations grow, and the climate changes, cities all over the world need to find ways to increase their water supply. OCWD’s innovations in purifying used water fulfill an international need, as well as addressing drought and seawater intrusion right here at home.