Survey on Sanitary Condition of Water in Domestic Solar Water Heater in Use

[Objective]To understand the quality of home solar heater,so as to guide people to use solar heater properly.[Methods]A total of 458 domestic solar heaters were sampled in Zaozhuang city from January to October in 2011.The in storage tanks were gathered.GB/T 5750-2006 Standard Method of calibration of drinking water was used to test sensory indices,toxicological indices,chemical indicators and bacteriological indicators.Then evaluation was made.The passing rate of nitrite was below 0.005 mg/L.[Results]Among 458 samples,243 were qualified.The qualified rate was 53.06%.The qualified rate of regular brand was 62.65% and the rate of irregular brand was 27.78%(P0.01);The qualified rate in food grade stainless steel tanks,aluminum alloy tanks and other material tanks was 70.43%,20.80% and 15.63% respectively(P0.01).The qualified rates of samples in containers that have been used for less than one year,2-3 years,4-5 years and more than 5 years were 44.90%,63.11%,58.16%,41.24% respectively(P0.01);The qualified rates of samples at the temperature from 0-30 ℃,from 31-50 ℃,from 51-70 ℃,higher than 71 ℃ were 60.76%,44.93%,46.83%,64.35% respectively(P0.01);The qualified rates of samples in one container that have been kept for 1-2 days,3-4 days and more than 5 days were 67.37%,45.16%,and 28.57% respectively(P0.01).The qualified rate of various indexes in odor was 63.75%,visible substance was 69.21%,nitrite was 77.95%,arsenic was 94.32%,plumbum was 92.79%,mercury was 96.29%,iron was 82.75%,manganese was 88.43%,oxygen consumption was 90.83%,total bacterial count was 70.74%,coliform group was 74.89%.[Conclusion]The qualified rate of in domestic solar heater is low.It can not be used as drinking water.