December 2025: Essential Updates to Water Quality Standards for Environmental Health and Safety

With December 2025 marking significant progress in international water quality management, five newly published standards deliver vital advancements for environmental health and safety. Covering best practices for ammonium nitrogen, nitrate, and total bound nitrogen analysis, these standards ensure improved water monitoring, regulatory compliance, and sustainable ecosystem management. Professionals across water utilities, laboratories, environmental agencies, and industry now have robust tools to safeguard public health and enhance operational excellence.

Overview / Introduction

Water quality management is fundamental to protecting public health, ecosystems, and industrial processes. Environmental health and safety standards are essential references for accurate monitoring and control of chemical substances in water, underpinning risk management strategies and regulatory enforcement worldwide. This December 2025 update introduces five critical standards, each bringing fresh insight and technological guidance into:

• Determination of ammonium nitrogen (NH4-N)
• Nitrate analysis via alternative colorimetric reactions
• Measurement of total bound nitrogen (ST-TNb) in diverse water types

In this article, industry professionals will find detailed analyses of each standard’s scope, requirements, and impact. Readers will also gain practical knowledge for testing procedure adoption, quality assurance, and regulatory alignment.

Detailed Standards Coverage

EN ISO 23695:2025 – Water Quality: Ammonium Nitrogen Determination by Small-Scale Sealed Tube Method

Water quality – Determination of ammonium nitrogen in water – Small-scale sealed tube method (ISO 23695:2023)

This standard provides the methodology for determining ammonium nitrogen concentrations in a wide range of water types—drinking water, groundwater, surface water, wastewater, bathing water, and mineral water. Utilizing the small-scale sealed tube method, it leverages the Berthelot reaction to generate a blue colorimetrically detected through photometry or spectrophotometry. Applicable for NH4-N concentrations from 0.01 mg/l up to 1,800 mg/l, the standard ensures high precision in the mid-application range and supports compliance with environmental directives and internal quality controls.

Key requirements include:

• Sample preparation steps to avoid ammonia loss or interference
• Use of salicylate or chlorophenol-based color reactions per manufacturer guidance
• Verification of calibration, interference checks, and system suitability

Who should comply:

• Environmental laboratories, municipal water suppliers, industrial wastewater managers, and regulatory bodies.

Practical Implications:

• Streamlined, reproducible measurement supports routine monitoring and regulatory reporting.
• Flexibility to choose sealed tube ranges best suited for intended NH4-N concentrations.

Notable Changes:

• Adoption of colloquial NH4 notation for consistency with typical practice
• Explicit interference and calibration guidelines for higher accuracy

Key highlights:

• Covers a wide range of water types and NH4-N concentrations
• Emphasizes quality assurance and laboratory safety
• Enables rapid, on-site or laboratory-based water ammonia analysis

Access the full standard:View EN ISO 23695:2025 on iTeh Standards

EN ISO 23696-1:2025 – Water Quality: Nitrate in Water Using Small-Scale Sealed Tubes, Part 1 (Dimethylphenol Color Reaction)

Water quality – Determination of nitrate in water using small-scale sealed tubes – Part 1: Dimethylphenol colour reaction (ISO 23696-1:2023)

Offering a precise method for nitrate determination as NO3-N across water sources—including natural, drinking, and wastewaters—this standard defines the dimethylphenol colorimetric approach using small-scale sealed tubes. Applicable for concentrations between 0.10 and 225 mg/l NO3-N, it serves laboratories and operators needing flexibility and adaptability based on instrumentation and sample origin.

Key requirements include:

• Adherence to specified measuring ranges for reliable results
• Color reaction-based detection for straightforward quantification
• Guidelines for sample dilution and interference control

Who should comply:

• Environmental testing labs, water supply utilities, wastewater treatment operators, compliance officers.

Practical Implications:

• Ensures compatibility with both manual and automated sealed tube test devices
• Clear conversion factors provided for regulatory compliance

Notable Changes:

• Common-language notation (NO3) adopted for clarity
• Stoichiometric conversion factors standardized for data reporting

Key highlights:

• Robust detection across wide nitrate ranges
• Flexible method selection for different water origins
• Unambiguous calibration and reporting protocols

Access the full standard:View EN ISO 23696-1:2025 on iTeh Standards

EN ISO 23696-2:2025 – Water Quality: Nitrate in Water Using Small-Scale Sealed Tubes, Part 2 (Chromotropic Acid Color Reaction)

Water quality – Determination of nitrate in water using small-scale sealed tubes – Part 2: Chromotropic acid colour reaction (ISO 23696-2:2023)

Focusing on a more specific nitrate measurement (0.20–30 mg/l NO3-N), this standard sets out the requirements for using chromotropic acid as the core color reaction in sealed tube testing. Especially pertinent for regulatory monitoring of surface waters, bathing waters, and treated wastewaters, it details procedures that ensure accuracy within restricted, lower concentration ranges—a must for environmental compliance.

Key requirements include:

• Defined procedures for preparation, reaction, and colorimetric measurement
• Mid-range result optimization for highest precision
• Sample adaptation through dilution to fit measuring range

Who should comply:

• Public health agencies, environmental assessment labs, waste treatment facility staff, compliance professionals.

Practical Implications:

• Enables reliable detection of environmentally critical nitrate levels
• Supports compliance with regional or international regulatory thresholds

Notable Changes:

• Explicit conversion factor instructions for regulatory equivalency
• Consistent notation for industry and compliance use

Key highlights:

• Suited for monitoring low-level nitrate pollution
• Chromotropic acid reaction enhances selectivity
• Standardizes laboratory approach across multiple manufacturers

Access the full standard:View EN ISO 23696-2:2025 on iTeh Standards

EN ISO 23697-1:2025 – Water Quality: Total Bound Nitrogen (ST-TNb) in Water, Part 1 (Dimethylphenol Color Reaction)

Water quality – Determination of total bound nitrogen (ST-TNb) in water using small-scale sealed tubes – Part 1: Dimethylphenol colour reaction (ISO 23697-1:2023)

This standard addresses the measurement of total bound nitrogen—including all organic and inorganic species—across groundwater, surface water, and wastewater. It prescribes the use of alkaline potassium persulfate oxidation followed by dimethylphenol color reaction, supporting concentrations from 0.5 to 220 mg/l ST-TNb. The result is critical for eutrophication studies, pollution assessment, and resource protection.

Key requirements include:

• Specification of digestion temperature and time for thorough nitrogen conversion
• Use of sealed tube or digestion tube for precise sample handling
• Standardized calibration and validation steps

Who should comply:

• Water quality laboratories, environmental research teams, wastewater treatment managers, regulatory compliance units.

Practical Implications:

• Facilitates reliable total nitrogen budgeting in environmental studies
• Reduces reporting ambiguity for multi-source nitrogen assessment

Notable Changes:

• Codifies best practices for sample digestion and reaction
• Incorporates industry-standard laboratory safety precautions

Key highlights:

• Comprehensive method for all nitrogenous species
• High flexibility for various water types and sources
• Data supports nutrient control and discharge permits

Access the full standard:View EN ISO 23697-1:2025 on iTeh Standards

EN ISO 23697-2:2025 – Water Quality: Total Bound Nitrogen (ST-TNb) in Water, Part 2 (Chromotropic Acid Color Reaction)

Water quality – Determination of total bound nitrogen (ST-TNb) in water using small-scale sealed tubes – Part 2: Chromotropic acid colour reaction (ISO 23697-2:2023)

Aimed at analysis within a 0.5–150 mg/l ST-TNb concentration range, this standard sets out procedures for the chromotropic acid color reaction post-oxidation, ensuring stringent, repeatable results for total bound nitrogen. This is essential for applications requiring tight nitrogen monitoring (e.g., effluent discharge, sensitive aquatic ecosystems).

Key requirements include:

• Strict temperature/time protocols for sample digestion (100°C recommended)
• Chromotropic acid color development followed by photometric measurement
• Sample preparation and dilution guidelines to prevent out-of-range errors

Who should comply:

• Laboratories focused on regulatory reporting, industrial water management, municipal treatment plant operators.

Practical Implications:

• Ensures comparability of results across different sites and manufacturers
• Ideal for low to medium nitrogen concentration monitoring

Notable Changes:

• Harmonized notation and common sample handling practices
• Emphasis on safety practices and detailed interference assessment

Key highlights:

• Delivers precision for sensitive environmental applications
• Supports full compliance with monitoring requirements
• Aligned with best practices in laboratory and field testing

Access the full standard:View EN ISO 23697-2:2025 on iTeh Standards

Industry Impact & Compliance

The December 2025 suite of water quality standards significantly strengthens regulatory alignment and quality control for organizations operating in environmental health and safety. By establishing uniform procedures for measuring ammonium nitrogen, nitrate, and total bound nitrogen, these standards provide:

• Consistent methodologies: Reducing result variability and ensuring comparable data across regions and sectors.
• Simplified compliance: Clear instructions minimize the risk of non-compliance and associated penalties.
• Efficient quality assurance: Laboratories can rapidly incorporate updated protocols, improve result accuracy, and enhance process validation.

Compliance considerations:

• Organizations should update their Standard Operating Procedures (SOPs) and staff training based on these new standards.
• Audits and accreditation processes (e.g., ISO/IEC 17025) will increasingly expect documented use of such updated methods.
• Transition periods may apply; advance adoption secures early compliance and operational stability.

Benefits of adoption:

• Protects public and environmental health by improving detection of nutrient pollution.
• Enhances reputation with regulators and clients for proactive risk management.

Risks of non-compliance:

• Legal exposure, financial penalties, or withdrawal of operating licenses.
• Loss of stakeholder trust due to outdated or unreliable analysis results.

Technical Insights

Common technical features:

• All methods rely on small-scale sealed tubes for easy, reproducible sample handling.
• Colorimetric detection provides rapid and precise measurement for both field and laboratory conditions.
• Emphasis on interference control and sample preparation safeguards analytical accuracy.
• Manufacturer flexibility: choose appropriate tube ranges and color reactions (dimethylphenol or chromotropic acid) for your specific application.

Implementation best practices:

1. Assess water matrix: Identify potential interferents (e.g., cations, organic matter) and select pre-filtration, dilution, or alternative digestion methods as needed.
2. Instrument compatibility: Use validated photometers or spectrophotometers matched to color reaction wavelengths.
3. Calibration and quality control: Follow strict calibration protocols, run control samples, and document results for audit and traceability.

Testing and certification considerations:

• Laboratories aiming for ISO/IEC 17025 accreditation should integrate these standards into their documented methods and training programs.
• Ensure reagent and apparatus procurement meets new standard specifications.

Conclusion / Next Steps

The December 2025 update to water quality standards represents a transformative step for environmental health and safety professionals. With clear protocols, modernized detection methods, and comprehensive compliance guidance, these standards drive higher quality analytics and regulatory assurance.

Key takeaways:

• Updated standards cover all aspects of ammonium, nitrate, and total nitrogen analysis
• Applicability extends from source waters to wastewaters, across all major industries
• Adoption is key for regulatory compliance and sustainable water management

Recommendations:

• Review and update internal procedures to align with each newly published standard
• Train laboratory and field staff on method selection, calibration, and quality control
• Explore, download, and integrate the official standards available from iTeh Standards into your compliance toolkit

Stay ahead in environmental compliance—explore the full standards and related guidelines on iTeh Standards today.