وَنَبِّئْهُمْ اَنَّ الْمَاۤءَ قِسْمَةٌ ۢ بَيْنَهُمْۚ كُلُّ شِرْبٍ مُّحْتَضَرٌ ( القمر: ٢٨ )
And inform them
(is) to be shared
Wa nabbi'hum annal maaa'a qismatum bainahum kullu shirbim muhtadar (al-Q̈amar 54:28)
And inform them that the water is shared between them, each [day of] drink attended [by turn]. (Al-Qamar  : 28)
1 Mufti Taqi Usmani
and tell them that water (of the well) is to be shared between them (and the she-camel), so as the right of having water shall be attended by each (alternatively).