Interpretation of the Latest "National Standard for Drinking Water Quality" (GB5749-2022)

The "Standards for Drinking Water Quality" (GB5749) serve as a key regulatory basis for drinking water quality supervision and management in China. The current version, "Standards for Drinking Water Quality" (GB5749-2006), hereinafter referred to as the "Original Standard," has been in effect since 2007/7/1—nearly 15 years—and has played a critical role in improving China's drinking water quality and ensuring its safety. In response to new developments in China's progress, evolving public expectations for a better life, and emerging issues encountered during implementation of the Original Standard, relevant authorities have revised the standard. The updated "Standards for Drinking Water Quality" (GB5749-2022), hereinafter referred to as the "New Standard," was published on 2022/3/5 and will officially take effect on 2023/4/1.

1. Implement requirements for standardized reform

To implement the Party Central Committee and State Council's requirements on deepening standardization reform and strengthening the technical standards system, in 2015 3, the State Council issued the "Reform Plan for Deepening Standardization Work," outlining overall reform goals, measures, and implementation arrangements. On 2018 1 1, the revised "Standardization Law of the People's Republic of China" came into effect, explicitly stipulating that mandatory national standards shall be established for technical requirements ensuring personal health and safety, national security, ecological environmental safety, and meeting basic needs of economic and social management. The state's standardization administrative department is responsible for initiating, numbering, and publishing these mandatory national standards.

The revision of the "Standards for Drinking Water Quality" was carried out under China's ongoing deepening of standardization reform, aligning with its key requirements. In terms of scope, drinking water is critical to public health and safety, as well as to economic development and social stability; thus, the new standard retains the same mandatory national standard status as the original. Regarding issuing authorities, while the original standard was jointly issued by the Ministry of Health and the Standardization Administration of China, the new standard is issued by the State Administration for Market Regulation and the Standardization Administration of China. In terms of content, the new standard removes Section 9 from the original standard, which outlined responsibilities of health departments at all levels and operational requirements for water supply entities regarding water quality testing. This change reduces administrative emphasis and refocuses the standard on technical requirements.

2. Narrow the gap in drinking water quality standards between urban and rural areas

In recent years, China's rural living environment has improved significantly, and the public's demand for better drinking water quality has grown increasingly strong. The Outline of the 14th Five-Year Plan for National Economic and Social Development of the People's Republic of China and Long-Range Objectives Through 2035 proposes: to establish a unified mechanism for planning, construction, and maintenance of urban-rural infrastructure, and to standardize basic public services and integrate systems across urban and rural areas; by 2035, the development gap between urban and rural areas and the disparity in residents' living standards will be substantially narrowed.

In the original standard, small centralized water supply was defined as centralized systems with a daily water supply of less than 1000 cubic meters (or serving fewer than 1 ten thousand people) in rural areas. It noted that due to constraints, certain water quality requirements for heterotrophic plate count, arsenic, and fluorides among 14 indicators were appropriately relaxed for both small centralized and decentralized supplies. The new standard redefines small centralized water supply as systems with a design daily capacity of less than 1000 cubic meters or serving fewer than 1 ten thousand people, removing the term "rural" and eliminating geographic restrictions. Replacing "daily water supply" with "design daily capacity" avoids inconsistencies caused by fluctuations in actual daily usage, offering greater accuracy. Additionally, the new standard states that when water sources or treatment conditions are limited, the following 4 indicators—heterotrophic plate count, fluorides, nitrates (as N), and turbidity—may be appropriately relaxed for small centralized and decentralized supplies. Overall, the new standard imposes stricter water quality requirements for these systems. However, narrowing the gap between water quality standards and actual water quality requires substantial effort. Improving drinking water quality in rural areas now faces new challenges and opportunities.

3. Reclassification and Updates to Water Quality Indicators

The new standard revises the "non-routine indicators" from the previous version to "extended indicators" to better reflect regional characteristics of drinking water quality and conditions under specific timeframes or circumstances. The total number of indicators has been adjusted from 106 in the original standard to 97 in the new one, comprising 43 routine indicators and 54 extended indicators. Key changes compared to the previous standard include the following:

Greater emphasis is placed on sensory indicators. Parameters such as color, turbidity, odor, and taste are closely linked to the drinking experience and user comfort. In recent years, water pollution has led to algal blooms in some water sources under specific conditions, causing odor and taste levels in drinking water to exceed limits and compromising water quality safety. Research shows that algal blooms often produce compounds like 2-methylisoborneol (MIB) and geosmin. These substances have low odor thresholds; when their concentration in water exceeds the threshold (10ng/L), they can cause distinct, highly noticeable odors that affect the sensory quality of drinking water. Therefore, the updated standard includes these two sensory indicators as expanded parameters.

Greater focus on disinfection by-products (DBPs). Certain organic compounds in water react with chlorine, chlorinating agents, ozone, and other disinfectants to form DBPs that pose carcinogenic, teratogenic, and mutagenic risks. To effectively control DBPs, the World Health Organization and various countries have established relevant laws and standards. In China's "Drinking Water Hygiene Standard" (GB5749-85), limits for chloroform were specified. The updated "Drinking Water Hygiene Standard" (GB5749-2006) expanded the range of DBP monitoring indicators, covering 14 items across both routine and non-routine categories. The new standard further upgraded five high-detection-rate DBPs—chlorodibromomethane, dichlorobromomethane, tribromomethane, trihalomethanes, dichloroacetic acid, and trichloroacetic acid—from non-routine to routine indicators to strengthen their regulation. Additionally, given the significant impact of ammonia concentration (expressed as N) on disinfectant dosing, it was also moved from non-routine to routine monitoring.

Greater focus on risk changes. The new standard adjusts indicators based on evolving water source risks and recent operational practices, reflected in "one addition and one subtraction." On the addition side, two expanded indicators have been introduced: acetochlor and perchlorate. Acetochlor is among the most widely used herbicides in China, with a usage history of over 20 years; it exhibits significant endocrine-disrupting effects, causing protein and DNA damage to animals and humans, as well as lipid peroxidation. Perchlorates are extensively used in fireworks, defense, fuel, aerospace, textiles, and smelting industries, and they strongly interfere with thyroid function, affecting human development. On the subtraction side, substances that have been banned from production and use in China for many years—based on recent detection data—are no longer included in the main body of the standard. These include trichloroacetaldehyde, sulfides, cyanogen chloride (expressed as CN-), hexachlorocyclohexane (total), parathion, methylparathion, lindane, DDT, formaldehyde, 1,1,1-trichloroethane, 1,2-dichlorobenzene, and ethylbenzene (12 items in total). These have been moved from conventional or unconventional indicators in the original standard to the new framework. Additionally, selenium, carbon tetrachloride, volatile phenols, and anionic synthetic detergents (4 items) have been shifted from conventional to expanded indicators. Furthermore, considering that Escherichia coli provides stronger indicator value than thermotolerant coliforms, the latter has been completely removed. Water quality reference indicators have been adjusted from 28 items in the original standard to 55 items in the new one. These adjustments enhance precision in water quality management, help avoid excessive allocation of human and material resources to low-detection-rate indicators across regions, and enable areas with higher risks for certain indicators to conduct continuous assessment and monitoring tailored to local conditions.

The limits for certain indicators have been raised. The new standard adjusted the limit values for 8 indicators in the main text, including nitrate (as N), turbidity, permanganate index (as O2), free chlorine, boron, vinyl chloride, trichloroethylene, and dimethoate. Compared with the previous standard: first, relaxations of limits under restricted source or water treatment conditions were removed. For example, the limit for nitrate (as N) in groundwater was previously relaxed to 20mg/L, turbidity was allowed up to 3 NTU when both source and treatment conditions were restricted, and chemical oxygen demand (CODMn method) was permitted at 5 mg/L when raw water quality was >6mg/L. Second, some indicator limits were increased. For instance, the upper limit for residual free chlorine in finished water was lowered from 4 mg/L to 2 mg/L; the limit for vinyl chloride was changed from 0.005mg/L to 0.001mg/L; the limit for trichloroethylene was changed from 0.07mg/L to 0.02mg/L; and the limit for dimethoate was changed from 0.08mg/L to 0.006mg/L. Additionally, considering the distribution of boron in China and its metabolic rate in the human body, the standard limit for boron was relaxed from 0.5mg/L to 1 mg/L (EU limit: 1 mg/L; WHO guideline: 2.4mg/L).

IV. Impact on the Water Supply Industry

(1) Increases water treatment costs and imposes higher demands on water supply system operations and maintenance.

Water treatment costs are driven by the expenses of controlling the most stringent indicators. Although this revision reduces the total number of indicators compared to the previous standard, the requirements for each indicator are stricter, which will increase production and operational costs for water supply enterprises. This places significant pressure on small and medium-sized plants in economically underdeveloped regions, those with poor water sources, or those with suboptimal management practices. The specific challenges include: (1) Current data on the occurrence levels and removal efficiency of 2 indicators, such as perchlorates and acetochlor, remain incomplete; (2) Moving disinfection by-products like bromochloromethane (6 items) and ammonia nitrogen from non-conventional to conventional categories, while imposing stricter limits on nitrate nitrogen, permanganate index, and other 7 indicators. These changes demand higher precision in coagulant and disinfectant dosing, as well as improved quality and stability of the distribution network; (3) The water industry has had limited time to adapt its testing capabilities to the new standards. Furthermore, the absence of specific clauses regarding test parameters and frequencies in the new standard may lead to inconsistent enforcement across different regions.

(II) Mismatch between existing water source quality standards and new standard indicators remains a significant issue.

The revised standard adds 5.3 clauses, stating that when source water quality fails to meet the requirements of "Surface Water Environmental Quality Standard" GB3838 and "Groundwater Quality Standard" (GB/T14848-2017), but utilization is necessary due to constraints, appropriate purification processes must be applied. The treated water must comply with this document's requirements. GB3838 has been in effect for over 20 years without adjustment, despite significant changes in environmental conditions and socio-economic factors. During this period, GB5749 was revised twice, and the 26 indicators in GB5749 (excluding disinfectants and their byproducts) are not reflected in GB3838, potentially resulting in situations where source water appears "compliant" yet remains difficult to treat with existing purification processes.

V. Recommendations

(1) Accelerate facility upgrades and management efficiency improvements to establish a high-quality water supply system.

All regions should conduct self-assessments of water supply quality against the new standards. For facilities that do not meet these requirements, analyze root causes across dimensions such as infrastructure quality, operations and maintenance (O&M) levels, and regulatory effectiveness: - If outdated infrastructure is the cause, develop a plan for plant upgrades and modernization, coordinate efforts to control public water network leakage, and gradually establish a high-quality water supply facility system. - If low O&M proficiency is the cause, strengthen professional training for technical and management staff, refine internal O&M policies and incentive mechanisms, leverage digital and smart technologies, and progressively build a refined water supply O&M system. - If water management deficiencies are the cause, clarify departmental responsibilities, enhance urban water supply regulations, improve government oversight capabilities, and boost efficiency in serving enterprises and the public, ultimately establishing a high-standard water supply management framework.

(II) Strengthen testing and emergency response capabilities to ensure water supply safety.

Continue improving the national urban water supply quality monitoring network, enhance testing capabilities at central, national, and local stations as well as among water suppliers, and strengthen urban water monitoring and early warning systems. Based on local water source risks and facility conditions, regions should promptly define expanded indicators and determine sampling locations, test items, and frequencies in accordance with the "Urban Water Supply Quality Standard" (CJ/T206). Further reinforce risk awareness and bottom-line thinking, improve emergency response plans for water supply, bolster emergency response capabilities, and elevate overall water supply security levels.

(III) Improve the water pricing mechanism to promote sustainable development of the water supply industry.

In some cities, water prices have remained unchanged for years or even decades, creating severe price distortions. This not only hinders water conservation efforts but also limits utilities' capacity to invest in upgrading infrastructure, ultimately affecting water quality. To implement the "Administrative Measures on Urban Water Supply Pricing" and the "Measures for Cost Supervision of Urban Water Supply Pricing," it is essential to refine the tiered pricing system for residential water use. This will leverage price mechanisms to promote water conservation, regulate demand, and curb unreasonable consumption. The regulatory cycle for urban water supply prices shall generally be 3 years. Where calculations indicate a need for adjustment, prices should be adjusted promptly. For significant adjustments, phased implementation is permitted.

(4) Expedite the revision of relevant standards to ensure seamless alignment.

Urban water purification facilities involve numerous process steps with scientifically rigorous and tightly coupled interdependencies. Once commissioned, operational parameters can be optimized, but such adjustments are inherently limited. Water treatment plants are not "universal solutions"; the quality of treated water is guaranteed only when source water meets required standards. We recommend promptly revising GB3838 to strengthen protection of source water areas, particularly Class I protection zones, ensuring alignment between source water quality standards and drinking water hygiene standards. Simultaneously, accelerate revisions to relevant industry standards to clarify requirements for source water quality, monitoring, purification, and management.