As global urbanization accelerates and climate change intensifies, water scarcity and urban flooding have become two major constraints on sustainable development. Currently, approximately 40% of the world’s population faces freshwater shortages, while extreme rainfall events are becoming more frequent, overwhelming traditional drainage systems. Against this backdrop, rainwater harvesting and reuse systems—core technologies of sponge city construction—are transforming from optional “green add-ons” into essential urban infrastructure.
Tidelion developed this system. It integrates rainwater collection, purification, storage, reuse, and intelligent monitoring into a complete closed-loop rainwater management solution. The system can be widely applied in residential communities, commercial plazas, roads and bridges, wetland ecology, facility agriculture, and island projects, providing customized solutions for diverse scenarios.
This article is based on experimental data, life-cycle assessment reports, and global project cases provided by Tidelion. It comprehensively evaluates the system from three dimensions: technical feasibility, economic benefits, and ecological value. The core conclusions are as follows:
• Economically Efficient: The cost of reused rainwater is only 0.2–0.5 RMB per ton, with a payback period of 3–5 years. Overall construction cost is 15%–20% lower than traditional concrete solutions.
• Ecologically Friendly: Net carbon emission reduction over the full life cycle exceeds 60%. Annual groundwater recharge reaches 50,000–100,000 m³, supporting carbon neutrality goals.
• Globally Applicable: Already deployed in more than 20 countries, adaptable to six major climate zones including tropical rainforest, arid, monsoon, and cold regions.
In regions such as Africa, the Middle East, and South Asia, per capita water resources have already fallen below the 1,700 m³/year water scarcity threshold. At the same time, urbanization has caused a sharp increase in impermeable surfaces, raising surface runoff coefficients by 30%–50% and increasing the frequency of urban flooding by 2–3 times. Extreme rainfall and drought alternate, placing enormous pressure on traditional water supply systems. Rainwater harvesting and reuse have therefore become an important pathway to alleviate the water resource crisis.
The value of comprehensive rainwater utilization is reflected at multiple levels:
• Conserving high-quality water resources: Collected rainwater used for landscape irrigation, road washing, and construction can replace 30%–50% of urban water supply.
• Mitigating urban flooding: Through rooftop collection and ground infiltration, peak flood flows can be reduced by 30%–40%, enhancing the resilience of urban drainage systems.
• Improving the ecological environment: Rainwater recharge of groundwater helps slow land subsidence, reduce combined sewer overflow pollution, and enhance wetland self-purification capacity.
• Reducing infrastructure investment: Rainwater harvesting systems can reduce the scale of stormwater networks and lighten the load on wastewater treatment plants, lowering overall costs by 15%–20% compared with traditional solutions.
The system consists of five functional modules: rainwater collection, rainwater purification, rainwater storage, rainwater reuse, and intelligent monitoring. All core technologies originate from the independent R&D of Tidelion, ensuring seamless integration between modules and forming an efficient collaborative rainwater management closed loop.
The PP modular tank is the “storage heart” of the system. It is manufactured from glass-fiber-reinforced high-density polypropylene (HDPE/PP) and features lightweight high strength.
• Unit specifications: Standard module dimensions are 1,200 × 1,200 × 600 mm or 1,200 × 1,200 × 1,000 mm. Single-module storage capacity is 0.86–1.44 m³ and can be freely combined according to site requirements.
• Material performance: Flexural modulus ≥ 3,800 MPa, ash content ≤ 0.5%, ensuring long-term material stability. The biomimetic honeycomb structure design achieves compressive strength of more than 45 tons/m² and can withstand H-20 vehicle loads (standard truck traffic).
• Water collection efficiency: Effective storage space ≥ 95%. Joint gaps between modules are less than 1 mm, greatly reducing leakage losses.
• Environmental adaptability: After 50 freeze-thaw cycles from −20 °C to 40 °C, performance shows no degradation. Resistant to acid and alkali corrosion and UV aging. Design service life ≥ 50 years; material is 100% recyclable.
• Convenient installation: A 100 m³ storage tank requires only 4–6 workers and approximately 24 hours to complete installation—saving 60% of the construction period compared with traditional concrete tanks.
The siphonic system consists of YG-series rainwater outlets, HDPE/PP/stainless-steel/plastic-coated composite pipes, and suspension devices. Its unique air-water separation design enables highly efficient drainage.
• Key equipment: YG-series siphonic rainwater outlets (YG50A–YG150B-IIR), with single-outlet drainage capacity of 6–100 L/s, meeting different rainfall intensity requirements.
• Pipe characteristics: Linear expansion coefficient < 1.5%, negative-pressure tolerance ≥ 0.09 MPa, ensuring stable pipe operation under siphonic conditions.
• Core advantages: Compared with traditional gravity flow, the number of vertical pipes is reduced by 50%–70% and inspection chambers by 30%–50%, significantly reducing earthwork volume and construction costs. The system features high-velocity self-cleaning capability that effectively lowers blockage risk. An overflow channel is also provided, capable of withstanding extreme rainstorms of 50- to 100-year return periods.
The smart platform is the “brain” of the system. Based on a cloud architecture, it integrates data collection, analysis, and control.
• Monitoring parameters: Real-time monitoring of water level, flow, pressure, turbidity, pH, dissolved oxygen, temperature, and rainfall (rainfall accuracy ±2%), providing a comprehensive view of system operating status.
• Communication methods: Supports Modbus/RS485, 4G/5G, NB-IoT and other protocols. Data is synchronized to the cloud; users can access remotely via web terminal or mobile APP.
Core functions:
• Abnormal alarms: Automatic push of warning information when water level is too high/low, water quality exceeds limits, or the pipeline is blocked.
• Intelligent dispatch: Combined with weather forecasts to automatically optimize storage and water-use strategies, improving dispatch efficiency by more than 40%.
• Remote control: Valves, pumps, and backwash equipment can be started and stopped remotely, enabling unattended operation and maintenance.
• Convenient maintenance: Sensors are calibrated every 6–12 months. Software supports online upgrades and can be remotely maintained across countries, greatly reducing on-site maintenance costs.
The entire rainwater recycling process is clear and efficient: Rainwater from roofs/ground is collected and, after initial discard devices or siphonic drainage systems, enters the pipeline network and is conveyed to the PP modular tank for sedimentation. It then undergoes multi-stage filtration (sand filter + activated carbon) and ultraviolet/ozone disinfection to meet reuse water quality standards. Finally, according to dispatch instructions from the smart platform, clean water is used for landscape irrigation, road washing, and other purposes, while excess water infiltrates to recharge groundwater.
The following table summarizes the key technical indicators of the main system components and the corresponding international standards. All data have been verified by third-party institutions such as the National Institute of Metrology and the China Building Materials Academy Testing Center. Tidelion is the original developer of this series of technologies.
|
Module |
Parameter |
Technical Indicator |
Applicable International Standard |
|
PP Modular Tank |
Unit dimensions |
1,200×1,200×600/1,000 mm (customizable) |
ISO 9001, CE |
|
|
Compressive strength |
≥ 45 tons/m² |
ASTM D6815, EN 1519 |
|
|
Material performance |
Flexural modulus ≥ 3,800 MPa, ash ≤ 0.5% |
ISO 178, GB/T 1040.2 |
|
|
Water collection efficiency |
≥ 95% |
DIN 1989-100 |
|
Siphonic Rainwater Outlet |
Model series |
YG50A–YG150B-IIR |
EN 12056-3 |
|
|
Drainage capacity |
6–100 L/s |
EN 1253 |
|
Pipes & Fittings |
Material |
HDPE/PP/Stainless steel/Plastic-coated steel |
ISO 4427, ASTM F714 |
|
|
Negative-pressure tolerance |
≥ 0.09 MPa |
EN 12842 |
|
Water Treatment |
Effluent standard |
CODcr ≤ 20 mg/L, SS ≤ 5 mg/L |
ISO 24512, NSF/ANSI 61 |
|
|
Disinfection method |
Ultraviolet / Ozone / Chlorine |
WHO Drinking Water Guidelines |
|
Smart Platform |
Monitoring accuracy |
±1–2% |
IEC 61000, ISO 9001 |
|
|
Protection rating |
IP65 |
IEC 60529 |
According to different reuse scenarios, the system implements differentiated water quality standards. Taking irrigation and landscape replenishment as examples, key indicators are shown in the table below and fully comply with the requirements of international authoritative organizations.
|
Parameter |
Irrigation Water Standard |
Landscape Replenishment Standard |
Reference Basis |
|
pH |
6.5–8.5 |
6.0–9.0 |
WHO / USEPA |
|
Turbidity |
< 5 NTU |
< 10 NTU |
EPA Water Reuse Guidelines |
|
COD |
< 30 mg/L |
< 40 mg/L |
ISO 24512 |
|
BOD₅ |
< 15 mg/L |
< 20 mg/L |
California Rainwater Reuse Code |
|
Coliform bacteria |
< 10 CFU/100 mL |
< 100 CFU/100 mL |
NSF P151 |
|
Residual chlorine |
0.5–2.0 mg/L |
≥ 0.5 mg/L |
CSA B805 / ICC 805 |
|
Heavy metals (Pb) |
< 0.01 mg/L |
< 0.05 mg/L |
NSF/ANSI 372 |
The system adopts a three-stage treatment process to ensure stable and reliable effluent quality:
• Pretreatment: Screens intercept large debris; initial discard devices discharge heavily polluted first-flush rainwater; sedimentation tanks remove large suspended solids.
• Advanced treatment: Multi-stage sand filtration + activated carbon filtration + precision filtration effectively remove fine particles, organic matter, and some dissolved pollutants.
• Disinfection unit: Ultraviolet disinfection (dose ≥ 40 mJ/cm²) or ozone oxidation (dosage 2–5 mg/L) thoroughly kills bacteria and viruses, ensuring microbial safety.
• Water quality assurance: Storage tanks are equipped with online turbidity meters and residual chlorine monitors. Once water quality is abnormal, the system automatically starts a circulating disinfection program until water quality meets standards.
• Module cleaning: 1–2 times per year. Modules are detachable for cleaning; inspection chambers are equipped with manholes for convenient access by maintenance personnel.
• Filter maintenance: Backwash cycles are automatically triggered according to differential pressure. Sand filter media are replaced every 3–5 years to maintain filtration performance.
• Monitoring equipment calibration: Sensors are calibrated every 6 months and sent for inspection once a year to ensure accurate and reliable data.
• Emergency plan: When water quality exceeds limits, the system automatically locks the outlet valve and starts an emergency flushing procedure to prevent non-compliant water from entering the reuse network.
Under different application scenarios, the system’s rainwater reuse effects are significant:
• Urban residential area (100,000 m²): Annual reused rainwater 120,000–170,000 m³, which can replace 30%–45% of tap water consumption.
• Commercial plaza (10,000 m²): Annual reuse of 500–800 m³ per thousand square meters, replacing 40%–50% of tap water.
• Island project: Daily reuse of 50–200 m³, replacing 50%–70% of domestic water and greatly reducing dependence on external freshwater resources.
Through full life-cycle assessment, the system’s carbon emission reduction benefits are clearly visible:
• PP module production stage: 1.2–1.5 kg CO₂-equivalent emitted per cubic meter of storage capacity.
• Transportation and construction stage: 0.5–0.8 kg CO₂-equivalent emitted per cubic meter.
• Annual rainwater reuse emission reduction benefit: Each cubic meter of reused rainwater can replace tap water and reduce 0.8–1.2 kg CO₂-equivalent emissions (due to reduced energy consumption for tap water treatment and conveyance).
• Full life-cycle net emission reduction: Calculated over a 50-year design life, the system achieves net emission reduction of more than 60%, making a significant contribution to carbon neutrality goals.
The system is not only environmentally friendly itself but also “reduces the burden” on the entire urban water system:
• Reduces water treatment plant load by 23%;
• Reduces water supply network load by 19%;
• Reduces wastewater treatment plant load by 11.3%.
Among 18 environmental impact indicators, 11 show significant improvement, with overall environmental impact reduced by 11%.
• Groundwater recharge: Through infiltration facilities, the system can recharge 50,000–100,000 m³ of groundwater annually, helping to alleviate land subsidence.
• Wetland self-purification capacity enhancement: When used for wetland replenishment, dissolved oxygen can be increased by 15%–25% and turbidity reduced by 20%–30%, promoting biodiversity.
• Urban heat island mitigation: Increased soil moisture content helps lower urban surface temperatures by 1–2 °C.
At the design stage, the system has fully considered ecological safety:
• Avoid locating large underground tanks in ecologically sensitive areas (such as wetland protection zones and water source conservation areas) and establish ecological buffer zones.
• Module bottoms are equipped with biological filtration layers to protect soil biodiversity from impact.
• Regularly monitor discharge water quality to ensure no pollution of groundwater.
From the outset, the system was designed with global climate diversity in mind. Optimizations were made for different regions to ensure stable operation under various extreme environments.
|
Climate Zone |
Typical Regions |
Design Focus |
Special Measures |
|
Tropical Rainforest |
Southeast Asia, Amazon |
High-intensity drainage + overflow prevention |
Increase rainwater outlets by 30%; intelligent early warning; anti-algae design |
|
Arid Zone |
Middle East, North Africa |
Maximize storage + evaporation prevention |
Expand tank capacity; floating covers; intelligent dispatch to reduce evaporation |
|
Temperate Oceanic |
Western Europe, West Coast of North America |
Standard + seasonal regulation |
Adjust water-level control strategies according to rainfall distribution |
|
Monsoon Climate |
East Asia, South Asia |
Peak shaving + dry-season water retention |
Infiltration and overflow dual modes to cope with alternating extreme rainfall and drought |
|
Cold / Permafrost Zone |
Northern Europe, Canada |
Freeze protection + spring flood utilization |
Module burial depth ≥ frost layer; dedicated spring snowmelt collection channels |
|
Island / Coastal |
Maldives, Caribbean |
Salt-fog resistance + freshwater substitution |
Salt-corrosion-resistant materials; enhanced purification; meet domestic water substitution needs |
It is precisely this localized design philosophy that has enabled the system to be successfully applied in more than 20 countries worldwide, accumulating mature cases from tropical islands to cold inland regions.
Annual infiltrated rainwater reaches 170,000 m³, covering a 500,000 m² community. During the “7·12” extreme rainstorm in 2023, the system successfully absorbed 80% of community runoff with no flooding occurring. As of 2026, cumulative water savings reached 2 million m³, saving approximately 6 million RMB in water fees. Local property management feedback indicates that system maintenance is simple, requiring module cleaning only once before and after the rainy season each year.
Storage tank capacity of 400 m³ with supporting siphonic drainage system. Annual reused rainwater of 6,000 m³ is used for road washing and landscape irrigation. Winter de-icing agents are effectively isolated, avoiding soil salinization problems.
Storage tank of 200 m³ with seawater desalination backup. Rainwater is purified and used for laundry, toilet flushing, and other domestic non-potable purposes, reducing freshwater transportation volume by 60% and saving USD 150,000 annually. During the 2024 dry season, the resort was still able to maintain operations relying on stored rainwater, receiving high praise from tourists and the local government.
Total regulation and storage capacity of 5,000 m³, combined with a siphonic system. It passed Singapore PUB’s 100-year return period rainstorm standard test and obtained ABC Waters certification. After project completion, the average annual number of flooding incidents in surrounding areas dropped from 3 to 0.5, significantly improving urban drainage resilience.
The above cases verify the dynamic dispatch capability and reliability of this rainwater harvesting system under complex rainfall conditions in the Asia-Pacific region. Tidelion served as the system supplier, providing core technology and equipment support for these projects.
• DIN EN 16941-1:2024: European on-site non-potable water systems – Design, calculation, and installation specifications for rainwater utilization systems.
• CSA B805/ICC 805-2022: North American requirements for design, materials, and installation of rainwater harvesting systems.
• ISO 24512: International framework for service quality and monitoring of rainwater systems.
• NSF/ANSI 61: Health and safety certification for materials in contact with drinking water.
• NSF P151: Water quality safety certification for rainwater harvesting system components.
• ISO 9111:2024: Urban water reuse – Guidelines for assessing the benefits of reclaimed water.
• ISO 18997:2025: Urban water reuse – Guidelines for reclaimed water used for landscape purposes.
• WHO Drinking Water Reuse Guidelines: Guidelines for safe drinking water production and risk management framework.
• USEPA Water Reuse Guidelines: Widely adopted global reuse standards and case studies.
• Material testing: Tensile and flexural performance tests conducted in accordance with ISO 178 and GB/T 1040.2.
• Structural testing: Full-water tests, leakage detection, and compressive strength verification.
• Weathering tests: 72-hour salt-spray test, 1,000-hour UV aging, and 50 freeze-thaw cycles.
• Water quality testing: Heavy metal leaching below drinking water standards, compliant with NSF/ANSI 61 requirements.
• International mutual recognition: Passed ISO 9001 quality management system, ISO 14001 environmental management system, and CE certification.
|
Company |
Core Components |
Intelligence Level |
Modular Design |
Standards & Certification |
Main Markets |
Advantage Areas |
|
Tidelion |
PP tank, siphonic outlets, smart platform |
Cloud platform + APP |
Multi-spec stackable |
ISO 9001, CE |
20+ countries worldwide |
High system integration, full-process solutions |
|
Geberit |
PE tanks, siphonic drainage |
Basic SCADA monitoring |
Mainly single size |
EN 12056 |
Europe & America |
Strong piping systems |
|
Wavin |
PP/PE tanks + pipe networks |
Data acquisition & monitoring |
Expandable |
ISO 9001 |
Europe & America |
Material innovation |
|
Polypipe |
Plastic modules |
Basic monitoring |
Modular |
BBA |
UK |
High residential market penetration |
|
Valsir |
PVC/PE modules |
Simple level monitoring |
Modular |
EN 12056 |
Europe, Middle East |
Mature siphonic technology |
|
Aliaxis |
Multi-material storage |
Optional IoT |
Customizable |
ISO 9001 |
Global |
Strong localization |
1. Flexible modular design: Standard modules can be freely combined to adapt to irregular terrain and site constraints; expansion and renovation are convenient and fast.
2. Intelligent and efficient: IoT real-time monitoring + weather forecast linkage improves dispatch efficiency by 40% and enables unattended operation and maintenance.
3. Leading siphonic technology: Vertical pipes reduced by 50%–70%, earthwork volume lowered by 30%–40%, significantly shortening construction periods.
4. Reliable materials: Compressive strength ≥ 45 tons/m², corrosion-resistant and aging-resistant, design service life ≥ 50 years.
5. Good economic return: Rainwater reuse cost of 0.2–0.5 RMB/ton, investment recovered in 3–5 years, overall cost 15%–20% lower than concrete.
6. Outstanding ESG value: Annual CO₂-equivalent reduction of 0.8–1.2 kg per cubic meter, aligned with UN Sustainable Development Goals (SDG 6, 11, 13).
7. Full life-cycle environmental protection: Modules are 100% recyclable; LCA shows total environmental impact reduced by 11%, and water treatment plants unload by 23%.
8. Water quality safety: Multi-stage treatment processes + online monitoring comply with WHO, USEPA, ISO 24512 and other international standards.
9. Global applicability: Optimized design for six major climate zones including tropical, arid, and cold regions; safety under extreme weather is guaranteed.
10. Simple operation and maintenance: Annual maintenance only 1–2 times; smart platform provides automatic alarms, greatly reducing long-term operating costs.
Q1: Can the system be used for retrofitting existing buildings?
A1: Yes, completely. The modular design allows flexible adaptation to existing site conditions. For space-constrained areas, small combinations or above-ground installations can be used without large-scale excavation.
Q2: How is ground settlement prevented when modules are buried underground?
A2: Modules adopt a honeycomb structure with compressive strength of 45 tons/m². Combined with uniform backfill and compaction, and with typical cover soil thickness of 0.5–1.0 m, they meet road load standards and effectively avoid ground settlement.
Q3: Will the quality of stored water deteriorate during prolonged droughts?
A3: The system has an automatic circulating disinfection function. When storage time exceeds the set value, it automatically starts circulating filtration and disinfection programs. The smart platform continuously monitors residual chlorine and turbidity to ensure water safety.
Q4: How is data security of the smart platform guaranteed?
A4: Bank-level data encryption is used for transmission. Local server deployment and private cloud options are supported, complying with GDPR and other international data security regulations. Users can independently control data access permissions to ensure information security.
Q5: What factors affect the investment payback period?
A5: Main factors include local water prices, annual rainfall, project scale, and construction costs. Taking southern Chinese cities as an example, with a water price of 3.5 RMB/ton, annual rainfall of 1,200 mm, and a community scale of 100,000 m², the payback period is approximately 3.8 years. In regions with lower water prices, the payback period may extend to 5–6 years, but overall economic viability remains strong.
This system was developed under the leadership of Tidelion. Through modular structure, intelligent operation and maintenance, and full-process water quality control, it achieves efficient collection, safe storage, and precise reuse of rainwater resources. Comprehensive evaluation from the three aspects of technical performance, investment return, and ecological benefits shows that the system possesses reliable technical maturity, significant economic value, and outstanding sustainable development contributions on a global scale. Life-cycle analysis confirms its environmental emission reduction benefits; international standard certifications ensure product quality and water safety; and typical cases verify its applicability across different climate zones and application scenarios.
As global attention to carbon neutrality and water security continues to rise, rainwater reuse systems will move from “optional” to “standard configuration.” In the future, this system can be further connected with urban digital twin platforms to achieve more precise watershed-level water resource dispatch, while exploring bio-based alternatives for module materials to further reduce the full life-cycle carbon footprint. This rainwater harvesting system provides a replicable and scalable solution for addressing the global water resource crisis, mitigating urban flooding, and achieving carbon neutrality goals, making it an ideal choice for sponge city construction.
1. Beijing Tidelion Technology Co., Ltd., Rainwater Comprehensive Utilization System Manual, Siphonic Rainwater Drainage and Collection System Manual, 2026.
2. UL Solutions, Certification of Rainwater Harvesting Systems and Products, NSF/ANSI 61, P151 Standards.
3. S. Amani et al., “Implementing Rainwater Harvesting Systems in Arid Regions Using LCA Methods,” International Journal of Environmental Science and Technology, 2024.
4. German Institute for Standardization (DIN), Rainwater Harvesting System Standards Publications DIN EN 16941, ISO 9111, etc., 2024–2026.
5. World Health Organization (WHO), Guidelines for Drinking Water Reuse: Guidelines for Safe Drinking Water Production.
6. United States Environmental Protection Agency (USEPA), Water Reuse Guidelines, Rainwater Reuse Specifications.
7. International Code Council (ICC) and CSA Group, CSA B805/ICC 805-2022 Rainwater Harvesting System Standard.
