وَأَنزَلْنَا مِنَ السَّمَاءِ مَاءً بِقَدَرٍ فَأَسْكَنَّاهُ فِي الْأَرْضِ ۖ وَإِنَّا عَلَىٰ ذَهَابٍ بِهِ لَقَادِرُونَ (18)
(23:18) And We sent down rain from the sky in due measure and lodged it in the earth : *17 and We are able to take it away as We will. *18
*17) The "rain" may refer to the rainfall, which comes down every now and then. It may also refer to the great store of water which Allah sent down at the time of the creation of the earth to fulfil its various needs till the Last Day, and which still exists in the shape of seas, lakes, sub-soil water, etc. It is the same water which evaporates in summer and freezes in winter and is carried by winds from place to place and spread over the earth by rivers, springs and wells to cause the growth of multitudes of things, and then is again restored to the seas, lakes, etc. Neither has this store of water been decreased by a drop nor was there any need to increase it by a drop since its creation. Today it is too well known how water comes about by the combination of oxygen and hydrogen in a certain ratio. The question is why can't more water be produced when oxygen and hydrogen still exist in abundance in the world? Who caused them to combine in the proper ratio in the beginning to produce oceans of water and who now stops them from coming together to produce an extra drop? Then when water evaporates, who causes oxygen and hydrogen to remain combined .n water vapours even in the gaseous state. Have the atheists and polytheists, who believe in independent deities for water, air, summer and ! winter, any answer to this question?
*18) This is to warn that Allah is able to take away the water if He so wills, and deprive the world of its most important means of life. Thus, this verse is more comprehensive in meaning than verse 30 of Surah Al-hulk (LXVII):
"Ask them: Have you ever considered that if the water of your wells should sink down into the earth, who would then restore to you running springs of water?"