The water that flows or has a source such as a stream, a river, a well, or rain is pure so long as its essential qualities, that is its colour, smell and taste do not change. The water of ocean is pure for ablution. If a pool of water is two cubits (length of two arms) in length, two cubits in breadth, and two cubits in depth, nothing can render it impure and it is suitable for ablution and ghusl (ritual bath). Water contained in the measurements greater than mentioned above, e.g.; water tanks; is considered pure. But if the impurity overcomes the water and it is manifest in the hue of the water, or its stench, or in its taste, then it is impure for ablution. A pool of water measuring less than the above mentioned parameters can be easily rendered impure if any impurity alters its colour, taste or smell; after which the water cannot be used for ablution.

Water in which a living being (that has blood in it) has drowned and died and the water has undergone a change for the worse in hue, taste or odour then it is rendered impure and unfit for consumption and performing ablution. After the cadaver is removed from it and the water regains its purity and does not show any signs of impurity then it becomes fit for ablution. The water that is not potable but can be used for ablution is sea water. The water that is potable and can be used for the ablution and bathing is rain water. The water that is potable and can be used but is unfit for ablution is rose water or water having any fragrance or taste. If the change in water is due to weeds growing in it or remaining stagnant for a long period, or any other means that is not a cause of impurity, and it thereby becomes greenish or blackish in colour, then the water nevertheless is fit for ritual purifications. Indeed water becomes impure only by direct impurity polluting it.

Allah says, “Water by itself is pure.” If impurity enters it the rule is based upon predominance. If on the whole impurity predominates, the water is ritually impure; if, in the course of time, the impurity decreases and purity prevails, the water becomes pure.