The Prophet ﷺ, was asked about water (in desert country) and what is frequented by animals and wild beasts. He replied: When there is enough water to fill two pitchers, it bears no impurity.  

سُئِلَ رَسُولُ اللَّهِ ﷺ عَنِ الْمَاءِ وَمَا يَنُوبُهُ مِنَ الدَّوَابِّ وَالسِّبَاعِ فَقَالَ ﷺ إِذَا كَانَ الْمَاءُ قُلَّتَيْنِ لَمْ يَحْمِلِ الْخَبَثَ  

The Messenger of Allaah (sal Allaahu alayhi wa sallam) was asked about water in desert. He then narrated a similar tradition (as mentioned above).  

أَنَّ رَسُولَ اللَّهِ ﷺ سُئِلَ عَنِ الْمَاءِ يَكُونُ فِي الْفَلاَةِ فَذَكَرَ مَعْنَاهُ  

The Apostle of Allaah ( sal Allaahu alayhi wa sallam ) said: When there is enough water to fill two pitchers, it does not become impure. Abu Dawud said : Hammad b. Zaid has narrated this tradition on the authority of 'Asim ( without any reference to the Prophet)  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ إِذَا كَانَ الْمَاءُ قُلَّتَيْنِ فَإِنَّهُ لاَ يَنْجُسُ