California’s 2025 Safe Drinking Water Plan: Why Regenerable Ion Exchange Matters More Than Ever

The draft 2025 Safe Drinking Water Plan has now been issued – and it reaffirms what many communities and water agencies across California already know. Tackling groundwater contamination, particularly from hexavalent chromium (Cr-6) and nitrate in drinking water, remains a top priority.

Published every five years, the plan provides a strategic blueprint for maintaining and improving California’s drinking water quality. The State Water Resources Control Board held a public workshop on July 15 in Sacramento to present the plan and gather stakeholder input, with the written comment period open through to the end of August 2025. For utilities, regulators, and engineering consultants, this draft is more than a policy update – it’s a clear signal to act.

NITRATE AND CR-6 IN DRINKING WATER: STILL A WIDESPREAD AND URGENT CONCERN

The 2025 plan highlights persistent challenges with naturally occurring groundwater contaminants, including arsenic, nitrate contamination in California, and Cr-6 in drinking water – particularly in disadvantaged and rural communities. Nitrate contamination in California and regulation has a been a long-term concern, while Cr-6 in drinking water continues to pose serious compliance challenges, especially following the adoption of California’s final Maximum Contaminant Level (MCL) in 2024.

In California’s Central Valley, nitrate levels have exceeded public health thresholds in numerous small water systems, placing communities at risk of long-term exposure. Prolonged ingestion of nitrate-contaminated water is associated with serious health outcomes, including methemoglobinemia (“blue baby syndrome”) and potential links to certain cancers. According to the California Division of Drinking Water, the current nitrate MCL is 10 mg/L as nitrogen, placing increasing pressure on small and rural systems to implement robust treatment strategies.

REAL PROJECTS DEMONSTRATE LONG-TERM POTENTIAL

In Southern California, mobile home park systems such as Quiet Oaks are already using modular regenerable IX platforms to treat nitrate – real project examples showing how small community systems are addressing regional groundwater issues.

Many systems still rely on short-term fixes or conventional single-pass ion exchange, which can result in high operating costs, significant waste generation, and frequent resin replacement. A different approach is needed – one that’s built for long-term sustainability and lower lifecycle cost (LCC).

A containerized Envirogen MinX regenerable ion exchange (regen IX) system installed to support uninterrupted and safe water supply for smaller communities, such as those in California.

NOT ALL ION EXCHANGE IS EQUAL: WHY REGENERABLE IX IS DIFFERENT

Envirogen’s regen IX (regenerable ion exchange) solution – delivered through our modular MinX or SimPACK platforms – is specifically engineered for the treatment of nitrate removal from groundwater and hexavalent chromium regulation in California. Unlike traditional single-use IX systems, regen IX is a closed-loop system designed for high efficiency, reduced waste, and lower total cost of ownership.

Key advantages of regenerable IX over conventional IX:

• Regenerable resin beds: Eliminates frequent resin replacement and reduces hazardous waste
• On-site regeneration: No need for off-site handling or transport
• Lower lifecycle costs: Fewer consumables, less waste, and longer service intervals
• Proven regulatory compliance: Consistently delivers nitrate-N <10 mg/L and Cr-6 levels <10 µg/L
• Modular and scalable: The MinX and SimPACK systems are ideal for small and mid-sized utilities

This makes regenerable IX a standout solution for communities seeking reliable, compliant, and cost-effective ion exchange for groundwater treatment – particularly in response to California’s existing and newly adopted chromium MCL regulations.

ALIGNED WITH CALIFORNIA’S SAFE DRINKING WATER GOALS

Envirogen’s regenerable IX technology supports multiple focus areas outlined in the 2025 plan:

TIME TO ACT

The draft plan reinforces what’s at stake – and provides a platform for shaping California’s safe drinking water strategy. But for many utilities, compliance deadlines are fast approaching.

If your team is evaluating treatment solutions in the face of increasing regulatory pressure or aging infrastructure, Envirogen’s regen IX approach is already proven and regulator-accepted – successfully deployed across numerous municipal applications in California.

LEARN MORE ABOUT THE MINX AND SIMPACK REGENERABLE IX SOLUTIONS

Envirogen’s MinX and SimPACK platform is available in both regenerable and single-pass configurations – offering flexibility depending on your water quality goals, site conditions, and operational constraints. Designed for long-term nitrate removal from groundwater and to support compliance with hexavalent chromium regulation in California, our regenerable IX systems are field proven to reduce lifecycle costs and minimise waste, while still delivering reliable performance in groundwater and drinking water applications.

Regenerable IX is also a proven option for industrial water treatment in California, supporting operations that require scalable, low-waste solutions for nitrate and Cr-6 removal under evolving regulatory requirements.

• Learn how regenerable IX and SimPACK can help you meet both the nitrate and Cr-6 requirements – read our earlier article focused on hexavalent chromium regulation in California.
• Visit our SimPACK and MinX ion exchange page – for full technical details, configurations, and use cases.
• Watch our video walkthrough of the regenerable ion exchange system in action – particularly relevant to SimPACK installations, showing the staggered-bed design and on-site regeneration process.