Meaning of 水質 in Japanese

大気と水質の汚染の問題は住民の増加によってひどくなるだろう。
The problems of air and water pollution will be intensified by the growth of inhabitants.

その湖は水質汚染で悪名高い。
The lake is notorious for its contamination.

水道水で年1回、井戸水なら年2回の水質検査をお勧めします。
We recommend that mains water have a water-quality test carried out once a year, well water twice a year.