Ibn ‘Umar said that when God’s messenger 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.” Ahmad, Abu Dawud, Tirmidhi, Nasa'i, Darimi and Ibn Majah transmitted it. Another version by Abu Dawud has, “It does not become unclean.”
Source: sunnah.com
Other translations
Arabic
عَنِ ابْنِ عُمَرَ قَالَ سُئِلَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَنِ الْمَاءِ يَكُونُ فِي الْفَلَاةِ مِنَ الْأَرْضِ وَمَا يَنُوبُهُ مِنَ الدَّوَابّ وَالسِّبَاع فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «إِذَا كَانَ الْمَاءُ قُلَّتَيْنِ لَمْ يَحْمِلِ الْخَبَثَ» . رَوَاهُ أَحْمد وَأَبُو دَاوُد وَالتِّرْمِذِيّ وَالنَّسَائِيّ والدارمي وَابْنُ مَاجَهْ وَفِي أُخْرَى لِأَبِي دَاوُدَ: «فَإِنَّهُ لَا ينجس»
sunnah.com