For the tiny pollution of drinking water and its safety issue, the five aspects are comprehensively investigated, including water quality protection and improvement of drinking water sources, excellent purification for waterworks, advanced treatment, stabilizing distribution, and safety assessment, and many key technologies are invented, and thus the technical system for the safety assurance of drinking water comes into being primarily.

(1) Developing ecotype construction technology for the adjustment of water sources
The new idea is put forward that ecotype water sources are developed on the deserted beach of high salt content, which overcomes many disadvantaged factors, including high salt content in the soil and weak penetrability of the soil, strong wind and wave not beneficial to the growth of aquatic plants, deficiency of natural wet ground and seed sources of aquatic plants, high salt content in water led by seriously-polluted area sources around the water sources, and the soils are changed to improve the bottom soils, separated to prevented the salts against entering them, and immersed to reduce the extraction of salts in pools, and they are established to reduce the area of standing water, and the wave is eliminated to ensure the growth of plants, and the introduction and natural propagation and some other unit technology are integrated to develop the applied technical system constructed by water source ecosystem which is adjusted by the regions of high salt concentration. The technology has obtained obvious effects on the projects, and the survival rates of eight aquatic plants reach above 95%, and the growth status of 11 newly-added aquatic plants is good, and the propagation of aquatic plants is realized by natural propagation, and the biodiversity is increased step by step. There is a decrease in the chlorophyll A content which represents the nutritional level, and the concentration of soluble oxygen increases, and the water quality is obviously improved, which accords with national grade II standard for surface water, and there is a 30% decrease in the cost for the subsequent treatment of preparations in waterworks.

(2) Developing the technical system to strengthen the universal purification efficiency in waterworks
In consideration of some pollution issues of drinking water, including colloidal particles, permanent organic substances, endocrine disruptors, alga toxin which appear in recent years, the catalyzed ozonation is invented to completely degrade toxic and harmful organic pollutants and alga toxin in water, New enhanced coagulation method, micro-flocculation direct deep bed filtration and coagulating interception sedimentation technology are developed, which have excellent removal efficiency for water of low temperature and turbidity, especially for fine suspended particles. The method that the increased removal rates of related pollutants in water can assure the safety of subsequent chlorination used. The new process of preoxidation -congulating-sediment-filtration-disinfection has been applied and demonstrated in Beijing, Tianjin and Shenzhen.

(3) Developing advanced treatment technology for drinking water
For advanced treatment in waterworks, the ozone-active carbon advanced treatment process is investigated and developed. The key is to solve some key technological issues such as that the reciprocal roles of ozone oxidation and activated carbon adsorption are used to remove the remnants disinfection by-products, and then eliminate permanent organic substances, endocrine disruptors, metal organic compounds, bromates, microorganisms., which are retained in the universal process, and the advanced treatment process is optimized, and the treatment efficiency is increased to realize the safety assurance function of advanced treatment.

For the safety issues of drinking water in the user end, the key processes are created, including the catalyzed ozonation, membrane treatment, and catalytic photooxidation disinfection and etc., and formed an integrated assembly equipment system, which are successfully applied in dozens of biotopes.

(4) Safety assurance research on the delivery and distribution of drinking water
Systematic research is used to investigate the changing rules of chemical and biological indices during the delivery and distribution of drinking water, and compare the impacts of raceways with different materials on the water quality variation, and put forward the pollution control and water quality assurance method, which proves that when the proper pipe materials are used, and the quality of water out of waterworks is assured, and the remaining chloride is controlled, the delivery and distribution water quality may be assured.

(5) Developing the system method for the safety assessment of drinking water
Systematic consideration may be used for the chemical, biological and toxicological indices to develop the drinking water safety assessment system based on risk analytical method. (detailed in the achievement 5 of the report)