Ontario, CA — September 30, 2025 — Hydrologics, Inc. is pleased to announce that the City of Ontario, California, has signed a five-year contract to provide zero-discharge flushing (ZDF) services for its municipal water system. Hydrologicsis the nationwide leader in advanced water distribution system maintenance.
Hydrologics’ ZDF technology utilizes a closed-loop system that removes sediment, biofilm, manganese, and other deposits while returning disinfected water to the distribution grid — conserving essentially 100% of treated water. ZDF is an advanced process that restores and maintains distribution system water quality without the water waste inherent in traditional hydrant flushing. Conventional flushing can discharge an estimated 2 million gallons of potable water per week in systems comparable in size to that of Ontario.
“Ontario’s water department is investing in best-in-class technologies to meet both regulatory requirements and sustainability goals,” said Gunther Mueller, President of Hydrologics Inc. “Our zero-discharge process improves water quality, stabilizes chlorine residuals, and reduces customer complaints, while eliminating unnecessary water loss. For Ontario, that means conserving around 2 million gallons of water in each week of flushing and extending the performance life of distribution assets.”
Ontario’s adoption of ZDF directly supports their compliance with several regulations, including California Senate Bill 555 (SB 555), which requires annual validated water loss audits and implementation of loss-reduction measures. By eliminating traditional flushing volumes, Ontario reduces non-revenue water by an estimated15 to 20 acre-feet per year. Also, ZDF helps with the EPA Stage 2 Disinfectants and Disinfection Byproducts Rule (DBPR), by lowering sediment loads and improving chlorine residual management. ZDF also helps to fulfill AWWA C651 and C652 guidelines, which recommend unidirectional flushing and sustainable disinfection practices, and meets the conservation objectives of the State Water Resources Control Board’s Urban Water Management Plan (UWMP), ensuring water savings at scale.
“The cleanings have been going really well, and there has been a huge difference,” said a water-quality official for Ontario Municipal Utilities Company. “I wish we could do more at once. Our residents have been receptive and so far, there have been positive results, fewer complaints, and as always, no water wasted. I am pleased with the results.”
Hydrologics’ ZDF services include real-time monitoring of turbidity, chlorine residuals, and flow data. Each project generates documented maintenance reports that can be integrated into Ontario’s asset management system, providing verifiable water quality improvements, water loss reduction metrics, and compliance documentation.
By committing to zero-discharge flushing, Ontario projects a cumulative conservation benefit of about 2 million gallons of potable water saved in each week of flushing over the five-year contract period, while simultaneously maintaining system performance and regulatory compliance.