﴿فَأَسْقَيْنَاكُمُوهُ﴾

(and We give it to you to drink,) This means, "and We send it down to you fresh and sweet, so that you can drink it; if We had wished, We could have made it salty (and undrinkable)'', as Allah points out in another Ayah in Surat Al-Waqi`ah, where He says:

﴿أَفَرَءَيْتُمُ الْمَآءَ الَّذِى تَشْرَبُونَ - أَءَنتُمْ أَنزَلْتُمُوهُ مِنَ الْمُزْنِ أَمْ نَحْنُ الْمُنزِلُونَ - لَوْ نَشَآءُ جَعَلْنَـهُ أُجَاجاً فَلَوْلاَ تَشْكُرُونَ ﴾

(Tell Me! The water that you drink, is it you who cause it to come down from the rain clouds, or are We the cause of it coming down If We willed, We verily could make it salty (and undrinkable), why then do you not give thanks (to Allah)) (56:68-70). And Allah says:

﴿هُوَ الَّذِى أَنْزَلَ مِنَ السَّمَاءِ مَآءً لَّكُم مَّنْهُ شَرَابٌ وَمِنْهُ شَجَرٌ فِيهِ تُسِيمُونَ ﴾

(He it is Who sends water down from the sky; from it you drink and from it (grows) the vegetation on which you send your cattle to pasture.) (16:10)

﴿وَمَآ أَنْتُمْ لَهُ بِخَـزِنِينَ﴾

(and it is not you who are the owners of its supply.) The meaning is, "You are not taking care of it; rather We send it down and take care of it for you, making springs and wells flourish on the earth. '' If Allah so willed, He could make it disappear, but by His mercy He sends it down and makes it fresh and sweet, maintaining the springs, wells, rivers and so on, so that they may drink from it all year long, water their livestock and irrigate their crops.