Preface

Water is the basic element for human survival and the basic guarantee of social and economic development. The problem of drinking water pollution is diverse and complex. To provide safe and high-quality drinking water, water supply enterprises must take appropriate safety measures agaist the entire water supply system, from water sources,
water plants, pipe networks to faucets, and seek systematic technical solutions. The densely placed underground pipe network and secondary water supply system, though located near the end of the water supply system, are the key and weak links for the safe water supply, and also the difficult points in the study of drinking water safety.

    At present, the water quality of urban water supply in our country is generally good when the water is discharged from water plants, but water quality declines, to varying degrees, after entering the water distribution network. This is especially true for China’s current water supply system which uses surface water as the main raw water. Due to water source pollution, the addition of various agents (oxidants, coagulants, disinfectants) in the water purification process, and the technical limitations of the traditional water purification process itself, when the so-called "purified water" enters the water distribution pipe network, it reacted with pipe interior surface during its long time transportation. Many complex physical, chemical and biological interactions occur in this process produce physical deposition, electrochemical corrosion, biofilm growth, biological corrosion and the growth of animalcules etc. At the same time, various corrosion products and microorganisms interact with various disinfectants added to the water, various metal salts and xenobiotic pollutants brought into the factory water during water purification process,causing the water quality of the pipe network to go bad. Various water quality issues concerning water supply network have attracted the attention of relevant experts and industry players. The water quality issue of the water supply network will be a great challenge to water supply industry around the world in 21st century. Water quality assurance technology about water supply network has become a research focus. Research on safe drinking water distribution technology is of great significance for water plants to keep water purification effect and ensure the safety of drinking water at the end of the pipe network.

前 言

水是人类生存的基本要素，是社会和经济发展的基本保障。饮用水水质污染问题具有多样性和复杂性。向用户提供安全优质的饮用水，供水企业必须面向整个供水系统，从水源、水厂、管网到龙头全过程采取相应的安全保障措施，寻求系统化的技术解决方案。而密布于地下的供水管网和二次供水系统虽位于供水系统的末端，却是安全供水中的关键和薄弱环节，同时也是饮用水安全保障研究的难点。
        当前我国城市供水水质在水厂出水时总体是好的，但进入配水管网后就不同程度地发生了水质下降。特别对于我国目前以地表水源为主要原水的供水系统中，由于水源污染、净水工艺中各种药剂的添加（氧化剂、混凝剂、消毒剂）和传统净水工艺本身的技术局限性，致使所谓“净化水”进入配水管网后，在其长时间的输送过程中与管材内表面发生了各种复杂的物理、 化学和生物作用， 并表现为物理沉积、电化学腐蚀、生物膜生长与生物腐蚀及微小动物生长等，同时各种腐蚀产物微生物又与水中投加的各种消毒剂、水质净化过程中带入出厂水的各种金属盐类及外源污染物发生相互作用，从而导致管网水质发生变化，造成管网水质下降。给水管网中出现的各种水质问题已引起有关专家和业者高度重视， 管网水质问题将是 21 世纪对世界各国供水行业的极大挑战，给水管网中的水质保障技术已经成为研究热点。研究饮用水安全输配技术对保持水厂净水效果，保证管网末端饮用水质安全具有重要意义。