Is the water that changed because of the length of staying without being used pure?
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger, may Allah exalt his mention as well as that of his family and all his companions.
The water that was changed due to staying long without being used remains pure; it is pure in itself and it is a purifier. Ibn Taymiyyah, may Allah have mercy on him, said: 'The water that changes because of staying still and unused remains as it is in principle, (i.e. it is pure) according to the agreement of the scholars, may Allah have mercy on them.'
Allah Knows best.
Fatwa answered by: The Fatwa Center at Islamweb