WATER
in the air and in the soil . Elevated levels of air pollution also create conditions for particulates to stick to surfaces , which can cause atmospheric corrosion . In addition to improved corrosion resistance , thanks to its 2.2 % molybdenum content , Type 316L stainless steel offers a long-lasting clean and neat appearance when installed on the exterior of retrofitted buildings . One further factor is the broad availability of stainless steel products in China . In the past five years , Chinese tube and pipe manufacturers have increased three-fold . Installation of the new systems is supported through a publicly-funded campaign to overhaul residential areas built before 2000 to comply with new standards . The water authority aims to install compliant secondary systems for all Shenzhen residents by 2025 . In 2018 , Shenzhen ’ s Yantian District , home to 2.7 million people , became the first district with stainless steel secondary systems and increased tap water quality .
Beyond Shenzhen
Following in Shenzhen ’ s footsteps , a campaign to overhaul older secondary water systems took off nationwide in 2018 , targeting 110 million people from 160,000 residential areas over five years . 20,000 upgrades were completed in 2019 , while more than 40,000 followed in 2020 . The outbreak of Covid-19 sparked a new urgency to the campaign , furthering the government ’ s promotion of health and safety while also stimulating the economy . Greeted by general enthusiasm , the campaign is largely ahead of schedule , and more public funds will be available to sustain its long term viability . In total , over 200 million homes are targeted for secondary water system upgrades or installation . As a rough estimate , some 15,000 tonnes of molybdenum may be needed over the next five years to achieve these targets – an annualized average that would be equivalent to more than 1 % of all new Mo produced in 2020 . To further promote the stainless steel secondary water systems , the Shenzhen utility held a “ National Conference on Secondary Water Supply Systems ” . This conference brought together academics , utilities , and suppliers from across the country to study the Shenzhen case in depth . “ Shenzhen Water University ” , a platform for research and exchange for stakeholders in the water industry , also helps to promote Shenzhen ’ s approach . By acquiring shares in local water utilities across China , SWG hopes to export its successful model and advanced operational experience across the country . Already , water utilities in the cities of Fuzhou , Haikou and Zhuhai have shown a strong commitment to “ study Shenzhen ’ s experience ” , while several districts in Shanghai and Suzhou have made Type 316L stainless steel mandatory on a trial basis . In 2020 , the city of Hangzhou upgraded over 100 secondary water systems with a combination of Type 304 and Type 316 stainless steel components . Other cities and provinces , while mandating “ stainless steel grade 304 or higher ” in their local specifications , strongly recommend Type 316L for use in public buildings or external applications . Time is running out to secure enough clean water for future generations . But cases like Shenzhen highlight that solutions are available , even when the challenges seem insurmountable . The new stainless steel secondary water systems , sparkling in the sun as they climb up the side of the city ’ s high rises , are a visible reminder that clean water for all is possible .
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