Entrevista a Earle Hartling, water recycling coordinator at Los Angeles County Sanitation Districts
«Diversity of water sources is essential»
Earle Hartling has had a long career at the Los Angeles County Sanitation Districts, where he held the role of Water Recycling Coordinator. He has been a key figure in driving wa ter recycling, aquifer recharge and potable reuse projects in southern California. His work has helped posi tion Los Angeles as a global leader in large-scale water reuse and sus tainability.
As Water Recycling Coordinator in Los Angeles for over 31 years, how would you summarise the main changes you have seen in this field?
When I started at the Los Ange les County Sanitation Districts in 1981, water reuse was still an afterthought. There was just one aquifer recharge project and a few non-po table uses for irrigation and industrial purposes. The severe drought of 1976-1977 pushed local water agencies to expand the use of reclaimed water, initially supplying it to locations near the reclamation plants. As the cost of drinking water increased and supplies diminished, recycled water systems expanded within cities and then throughout the region, eventually forming inter connected megasystems.
When I retired in 2023, we had nearly 900 points of direct non-potable use, over 271 miles of distribution pipelines, and an aquifer recharge project that had nearly doubled capacity. Similar growth occurred in neighbouring institutions such as West Basin and Las Virgenes, and the cities of Glendale and Burbank.
At the institutional level, the sector also matured. In the 1980s, a small group of institutions formed water reuse associations and held mod est annual conferences. Eventually, these merged into the WateReuse Association, which now has more than 500 members across 38 states and 11 different countries, and organises conferences that draw almost a thousand attendees.
Public acceptance has grown dramatically. Initial resistance to using “treated wastewater” gave way to widespread support, as recurring droughts, water restrictions and decades of safe operation demonstrated the necessity, reliability and safety of recycled water. Today, com munities often ask for more.
How has water reuse helped to sustain the Los Angeles metropolitan area?
Water has always limited the growth of Los Angeles. Insufficient local reserves forced the region to rely on water imported from dis tant basins, while rapid population growth, droughts, overexploitation of aquifers and competition between states placed these sources under an increasing amount of strain.
In response, sanitation institutions began to put high-quality recycled water to productive use instead of discharging it into waterways. By 2023, reclaimed water represented approximately 10% of Los Angeles County’s total water supply. With the projects that are currently under construction or in development, this share could easily double or even triple, making recycled water one of the most reliable local sources.
What is the best way to communicate the risks to society?
Communicating the risks associated with drinking water is just as important as managing them technically. The way information is communicated can make the difference between building trust and sowing doubt. The best way to talk about drinking water safety is to do it openly, clearly, consistently and responsibly, establishing genuine dialogue with the community.
Now that direct potable reuse is authorised in California, do you foresee its rapid deployment?
Not in the Los Angeles-Orange County region. Here, advanced treatment facilities are designed primarily for indirect potable reuse through aquifer recharge: a practice that has been employed safely since 1962. Large aquifers provide storage, serve as a buffer and give the public peace of mind.
Direct potable reuse on a “pipe-to pipe” basis would require extremely extensive real-time monitoring or large storage facilities, and could generate unnecessary controversy. A more likely step is to supply advanced treated water to raw-water reservoirs upstream, where it is mixed with imported resources before conventional treatment.
In regions without aquifers or reservoirs, however, direct potable reuse can be a solution.
What lessons can southern California offer Catalonia?
Diversity of water sources is essential. Even with multiple sources, southern California overexploited aquifers and saw imported reserves dwindle due to climate change and outdated distribution agreements. Recycled water offers a crucial cushion.
Although seawater desalination may eventually be necessary, reclaimed water can reduce and delay this need. It is much less energy intensive – requiring about a third of the energy needed for desalination – and is available for inland regions that do not have access to the ocean.
Southern California has served as a laboratory for water reuse technologies, public acceptance and institutional cooperation. Receiving international visitors, such as the Costa Brava Girona Water Consortium (CACBGI) and others from Catalonia, has helped to spread this knowledge around the world.
«Diversity of water sources is essential. Although seawater desalination may eventually be necessary, reclaimed water can reduce and delay this need and is much less energy intensive»
«Initial resistance to using “treated wastewater” gave way to widespread support, as decades of safe operation demonstrated the necessity, reliability and safety of recycled water»
