[Chinese Mainland] Pinghu Innovates Reclaimed Water Utilization: Annual Industrial Reclaimed Water Use Reaches 12.48 Million m³, "Inverted Tiered" Water Pricing Achieves Volume Increase with Price Reduction, and Under the Three-Tier Water Supply Framework

The Pinghu Water Conservancy Bureau 9月7日 released: As of 2025年, the city's industrial reclaimed water utilization volume reached 1248万 m³, which can save 16.7% of industrial raw water intake, freeing up more than 1600万 m³ of water resources and pollutant discharge quotas annually. The core approach is point-to-point closed-loop reuse + "Ultrafiltration + Reverse Osmosis" advanced treatment + "inverted tiered" water pricing with "higher volume, lower price". The industrial large-scale quality-differentiated water supply ratio in Dushangang Development Zone has reached 60%.

Reclaimed water being "applauded but not adopted" is a long-standing industry problem: facilities are built, but enterprises are unwilling to use them. Zhejiang Pinghu's solution is straightforward—rather than persuading enterprises to use more, it makes using more a financially worthwhile proposition. Focusing on water conservation and carbon reduction in the industrial sector, the city has built a utilization system centered on "quality-differentiated wastewater treatment and centralized high-quality regeneration" around three elements: planning and layout, facility construction, and policy improvement. It has explored a path of "trading water for space, promoting carbon reduction through water," and was selected as a typical case in the third batch of the Provincial Party Committee Reform Office's "Enhancing Ecological and Environmental Governance Capacity" program.

Diversified Allocation: Three-Tier Water Supply Framework + Point-to-Point Closed-Loop Reuse

Pinghu's first move is structural reform on the supply side. Leveraging its industrial agglomeration advantages, the city has built a 1.5万 m³/d reclaimed water project for the papermaking industry, creating a point-to-point closed-loop reuse model for wastewater within the same industry, achieving on-site treatment, nearby regeneration, and circular utilization—for industries like papermaking with large discharge volumes and relatively stable water quality, point-to-point reuse can minimize transmission costs and water quality fluctuation risks to the greatest extent.

On this basis, Pinghu has established a multi-source, quality-differentiated collaborative layout, creating a three-tier water supply framework of "high-quality water for livelihood, conventional water for basic needs, reclaimed water for industry," allowing reclaimed water to gradually replace high-carbon conventional industrial water. Currently, the city can save approximately 547万 m³ of fresh water resources annually, and the industrial large-scale quality-differentiated water supply ratio in Dushangang Development Zone has reached 60%.

Process Upgrading: Key Indicator Limits Reduced by More Than 85% Compared to National Standards

The second move is ensuring water quality. Pinghu adopts a "Ultrafiltration + Reverse Osmosis" high-standard advanced treatment process, continuing to upgrade beyond the Level 1A discharge standard for urban wastewater treatment plants, increasing the number of production water recycling cycles, and reducing pollutants such as TN, CODCr, and TP.

Two "by-products" are worth noting: first, it helps enterprises eliminate the internal secondary dechlorination step, significantly reducing equipment energy consumption and concentrate treatment costs; second, effluent quality is significantly improved—currently, key indicator limits such as chloride ions, sulfate, and total hardness are reduced by more than 85% compared to national standards, with annual reductions of COD, Total Nitrogen, and other pollutants by more than 1500 tons.

For water-using enterprises, chloride ions and total hardness directly affect the concentration ratio and scaling/corrosion risks of circulating cooling systems. Lower indicators mean equipment can operate at higher concentration ratios with less blowdown water, multiplying water-saving benefits.

Institutional Safeguard: "Inverted Tiered" Water Pricing—the More Used, the Lower the Unit Price

The third move, and the most groundbreaking one, is the pricing mechanism. Pinghu has introduced 4 supporting policies to precisely guide standard pricing, implementing "inverted tiered" water pricing and technical renovation subsidy policies:

• Segmented threshold setting—segmented thresholds for average daily water consumption are set separately based on enterprise water use conditions;
• Higher volume, lower price—enterprises exceeding thresholds receive tiered preferential pricing, where the greater the water consumption, the lower the unit price;
• Technical renovation subsidies—financial subsidies are provided for enterprise water-saving technical renovations to offset upfront investment.

This is completely opposite to the "increasing block rate" for residential water use (the more used, the more expensive), yet it precisely targets the core contradiction in reclaimed water promotion: reclaimed water projects have a high proportion of fixed costs, and only by increasing usage volume can unit costs be reduced. Using pricing to "buy" volume is essentially paying for economies of scale.

Enterprise-Side Ledger: Recycling Cycles Increased 4–5 Times, Annual Savings of Nearly 10 Million Yuan in Discharge Fees

The combined effect of policies and processes is already reflected in enterprise ledgers:

• Production water recycling cycles increased 4–5 times;
• Discharge volume reduced by more than 25%;
• Annual savings of nearly 1000万 yuan in discharge fees.

For the industrial park, reduced discharge volume brings another benefit—the freed-up discharge quotas can be used for new project implementation, which is the meaning of "trading water for space." At the city level, this model frees up more than 1600万 m³ of water resources and discharge quotas annually, and can save 16.7% of industrial raw water intake.

What Exactly Is Replicable

Among the three components of the Pinghu model, the process is a general-purpose component, the pricing mechanism is a customized component, and the industrial base is a prerequisite component.

• Point-to-point closed-loop reuse — suitable for industries with large discharge volumes, stable water quality, and proximity between water use and discharge points (paper making, textile printing and dyeing, food processing, etc.); the main barriers to replication lie in the pipeline network and land use;
• Three-tier water supply framework — requires regional authority over differentiated water quality supply planning and the capacity to invest in pipeline networks; more suitable for development zones with high industrial concentration and clear incremental demand;
• "Inverted tiered" water pricing — depends on the local government's fiscal capacity to absorb the price differential, as well as the price ratio between Reclaimed Water costs and tap water prices; this is a policy innovation, and replication requires recalculating the equilibrium point.

In other words, what is truly difficult to replicate is not the technology, but the fiscal determination to "pay for volume."

What It Means for Us: TIANYI TECH's Assessment

TIANYI TECH has long served municipal and Industrial Park wastewater treatment and Reclaimed Water Reuse clients. We recommend that clients, when designing Reclaimed Water solutions, address three questions upfront: first, define the tiered boundaries of differentiated water quality supply, and work backward from end use to determine treatment processes, avoiding a "one-size-fits-all" approach that applies the highest standard and causes investment waste; second, incorporate indicators such as chloride ions and total hardness that affect users' equipment operation into the design inputs, rather than focusing only on COD and ammonia nitrogen; third, promote the inclusion of a "volume-price linkage" mechanism in water supply and use agreements, using pricing to lock in baseline volumes so that the project's economies of scale become predictable. Ultimately, competition in Reclaimed Water comes down to competition in unit cost.

About TIANYI LIMITED: TIANYI TECH is deeply engaged in the fields of wastewater treatment and Reclaimed Water Reuse, committed to providing efficient, low-carbon, and sustainable water treatment solutions for municipal and industrial clients.