Abstract: The rural water supply in west China is facing with problems such as long transfer distance, small flow, and secondary pollution caused by long time stay of water in the regulation tank. In order to explore the impact of regulation tank made of different materials on water quality, we tested the variations of four water quality indicators (residual chlorine, pH, conductivity and dissolved oxygen) in different tanks made of concrete, tile, plastics and stainless steel, respectively. The results show that at given temperature, the attenuation coefficient of residual chlorine in concrete tank is the largest, followed by plastic, tile and stainless steel. The pH value also changes obviously: the pH value of water in concrete and tile regulation tanks shows an obvious rising trend with the increase of storage time, while in stainless steel tank the pH value increases gently, and in plastic tank the pH value does not change significantly. The water conductivity in concrete, tile and stainless steel tanks increases with time rapidly in the early stage, but the change becomes stable later. The variations of dissolved oxygen in concrete and stainless steel tanks are relatively stable, while in tile and plastic tanks, dissolved oxygen shows a trend of increasing. The effect of different tank materials on water quality and the variation of water quality with environmental factors are obtained. It could be a reference for the design, operation and management of rural water supply system.

Key words: regulation tank, water quality, material, rural water supply system, secondary pollution, pH value