Table 1 Classification of water quality evaluation results.

From: The present situation and pollution sources of underground drinking water in Zhangjiakou, China

Evaluation method

Evaluation result

I

II

III

IV

V

Comprehensive water quality index method

1 ~ 2

2 ~ 3

3 ~ 4

4 ~ 5

 ≥ 5

Weighted fuzzy comprehensive evaluation method

 < 1.5

1.5 ~ 2.5

2.5 ~ 3.5

3.5 ~ 4.5

 ≥ 4.5

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