WATER
agricultural use . The signature South-to- North Water Diversion Project , the costliest engineering work in human history , has shown only meager results in alleviating chronic water scarcity in Northern China ’ s densely populated plains . Shenzhen , with major pollution and an ever -growing population , knows these water woes all too well . Shenzhen does not have any deep major rivers , only rain-dependent surface waters , fed by seasonal monsoons . Quality and availability of water varies widely from month to month and year to year . The estuaries that once helped to clean and stabilize water levels have been drained for industrial development . Shenzhen must look for other solutions . By 2025 , the city hopes to increase the volume and quality of its water supply through capturing and reusing rainwater , better integration of stakeholders and maintenance practices , establishing new reservoirs and outfitting all residences with stainless steel secondary water systems .
Spotlight on Shenzhen
Shenzhen ’ s water utility identified the secondary water supply systems as key failure points during distribution . This is where energy consumption is highest , as well as where leakage and contamination are most likely to occur . The new secondary systems in Shenzhen are therefore fully automated , with flow meters and cameras installed at various points of the line to monitor rates and regulate valves and pumping capacity .
Made with galvanized steel , ductile iron or plastic , the original systems suffered from corrosion and leakage , leading to water loss and contamination . Photo © Fabio Ries
They are integrated into one smart control system together with the water works and the main municipal supply line . Trials for system replacement have been carried out in Shenzhen since 2010 in selected urban districts , before the complete campaign began in 2017 . After testing and comparing different materials , Type 316L stainless steel was specified as mandatory for all tubes , fittings and water tanks in secondary systems , no matter whether installed outside , underground or in the walls . For valves , pumps and meters , the use of Type 316L stainless steel is not yet mandatory but strongly recommended . The Shenzhen Water Group ( SWG ) chose Type 316L stainless steel for strength , resistance to corrosion , ease of maintenance and cleaning , long service life and recyclability . Corrosion is a major issue in Shenzhen due to its humid coastal location with a high salt content both
Thanks to stainless steel , the new systems look neat and are easy to clean and maintain . Photo © Fabio Ries
China ’ s secondary water system upgrade in numbers Countrywide , 200 + million homes need upgrades . 1st phase target ( 2019 – 2023 ): 160,000 residential areas 110 million people
By 2020 completed : 60,000 residential areas 41 million people
54 Valve World November 2022 www . valve-world . net