在农村牧区家家都有水缸，用缸储水虽给家庭生活带来方便，但若长期使用会给人体健康造成危害。水储存一段时间后，细菌便会在其中生长繁殖，这种水一经加热，细菌还会释放出硝酸盐还原酶。这种酶会将水中的硝酸盐还原为亚硝酸盐，这是一种致癌物质。据有关资料证明，刚出井的 In rural pastoral areas, every family has a water tank. Although it is convenient for family life to use water for tank storage, it will cause harm to human health if it is used for a long time. After the water has been stored for a period of time, the bacteria will grow and multiply therein, and upon heating, the bacteria will release nitrate reductase. This enzyme reduces nitrate in water to nitrite, a carcinogen. According to the data prove that just out of the well