Surat Al Hijr (21-22)

{وَإِن مِّن شَيْءٍ إِلاَّ عِندَنَا خَزَائِنُهُ وَمَا نُنَزِّلُهُ إِلاَّ بِقَدَرٍ مَّعْلُومٍ} (الحجر : 21)

21- Nothing on earth or in heaven but We have its treasures, and We only send it down with a fixed amount according to Our Wisdom, and Our Will destines it.

{وَأَرْسَلْنَا الرِّيَاحَ لَوَاقِحَ فَأَنزَلْنَا مِنَ السَّمَاءِ مَاءً فَأَسْقَيْنَاكُمُوهُ وَمَا أَنتُمْ لَهُ بِخَازِنِينَ} (الحجر : 22)

22- We have subjugated the wind to fertilize plants. Scientists proved that clouds do not send rains by themselves even if they are so moist, but when salty or snowy atoms exist and meet the moist windy mass (clouds), intensity is achieved and rain falls down. The wind brings these atoms and fertilizes clouds forming thunder by the command and destiny of Allah.

So, the wind fertilizes clouds to cause rain then water comes down to water you and to irrigate your plants and animals. Rain rests in Our Treasures not yours and it is in Our Hands not yours. Or the meaning is: You are not capable of maintaining this amount of water which Allah sends down, so He preserves it in fountains, wells, and rivers to take from it in the time of need.