A field survey was conducted to collect the drinking water samples from longevity and non-longevity counties of South China. For comparative analysis the drinking water was also collected from the non-longevity counties of North China. First, the percentage of centenarian to county levels was calculated from the national population census (NBS 2010). A total of 128 samples (Table 1) was collected that included 86% of groundwater (spring water and well water) and 14% of surface water (lake water, river water, and reservoir water). Samples collected from longevity areas accounted for 31% and the other 69% was collected from non-longevity areas.
Number of samples in the study areas
| . | Province . | County . | Lake water . | Reservoir water . | River water . | Spring water . | Well water . | Total . |
|---|---|---|---|---|---|---|---|---|
| North | Henan | Xinxiang | 6 | 6 | ||||
| Inner Mongolia | Xilinhot | 1 | 1 | |||||
| Shaanxi | Huxian | 7 | 7 | |||||
| South | Guangdong | Guangning | 31 | 31 | ||||
| Huaiji | 1 | 12 | 5 | 18 | ||||
| Sihui | 1 | 4 | 5 | 10 | ||||
| Sanshui* | 1 | 6 | 7 | |||||
| Guangxi | Bama* | 1 | 3 | 4 | ||||
| Donglan* | 3 | 1 | 9 | 13 | ||||
| Fengshan* | 2 | 1 | 1 | 4 | ||||
| Heshan | 1 | 1 | ||||||
| Nanning | 1 | 1 | ||||||
| Tianyang | 1 | 1 | ||||||
| Hainan | Chengmai* | 1 | 1 | |||||
| Lingao* | 4 | 4 | ||||||
| Sanya | 1 | 1 | 3 | 5 | ||||
| Jiangsu | Rugao* | 1 | 1 | 5 | 7 | |||
| Suzhou | 4 | 3 | 7 | |||||
| Total | 4 | 5 | 9 | 62 | 48 | 128 |
| . | Province . | County . | Lake water . | Reservoir water . | River water . | Spring water . | Well water . | Total . |
|---|---|---|---|---|---|---|---|---|
| North | Henan | Xinxiang | 6 | 6 | ||||
| Inner Mongolia | Xilinhot | 1 | 1 | |||||
| Shaanxi | Huxian | 7 | 7 | |||||
| South | Guangdong | Guangning | 31 | 31 | ||||
| Huaiji | 1 | 12 | 5 | 18 | ||||
| Sihui | 1 | 4 | 5 | 10 | ||||
| Sanshui* | 1 | 6 | 7 | |||||
| Guangxi | Bama* | 1 | 3 | 4 | ||||
| Donglan* | 3 | 1 | 9 | 13 | ||||
| Fengshan* | 2 | 1 | 1 | 4 | ||||
| Heshan | 1 | 1 | ||||||
| Nanning | 1 | 1 | ||||||
| Tianyang | 1 | 1 | ||||||
| Hainan | Chengmai* | 1 | 1 | |||||
| Lingao* | 4 | 4 | ||||||
| Sanya | 1 | 1 | 3 | 5 | ||||
| Jiangsu | Rugao* | 1 | 1 | 5 | 7 | |||
| Suzhou | 4 | 3 | 7 | |||||
| Total | 4 | 5 | 9 | 62 | 48 | 128 |
*Represents longevity counties.