It was narrated on the authority of Abu Hurairah, may Allaah be pleased with him, that the Messenger of Allaah, peace and blessing be upon him, said: "You should not pass urine in stagnant water which is not flowing then (you may need to) wash in it." [Reported by Al-Bukhaari and Muslim]
In another variant narration reported by Muslim: "None of you should take a bath in stagnant water when he is Junub ."
This is great Hadeeth has important issues related to the matter of purity of water that we will discuss in the following analysis:
Firstly, The Prophet, peace and blessing be upon him, has prohibited passing urine in stagnant water such as watering places and small streams in the desert. He, peace and blessing be upon him, said 'which is not flowing' to exclude the stagnant water that some of it is flowing.
Secondly, in that Hadeeth, the Prophet, peace and blessing be upon him, prohibited urinating in the stagnant water which is not flowing and the like. There is great wisdoms behind that prohibition. Amongst such wisdoms is that such water may not become impure, polluted and may be kept away from what such impurities cause i.e. the diseases that afflict people when using it.
Thirdly, it can be deducted from that Hadeeth the prohibition of taking a bath in the stagnant water, whether by immersing the whole body or part of it into it.
Fourthly, context indicates that there is nothing wrong with taking a bath in the water that is flowing, even through immersing such as rivers, seas and the like. The same ruling applies to urinating in it because that impurity does not cause harmful effects; however, it is better to avoid urinating in that water also. That is because much impurities may cause harms to that water through long time. Again, urinating in that water goes against the Islamic etiquette regarding answering the call of nature.
Fifthly, we come to know from that Hadeeth the prohibition of urinating in the stagnant water and then washing oneself in it. Is that for prohibition, where it is not permissible to wash oneself in it or for just Karaahah (disliking) i.e. if one does that this will be valid but disliked?
Scholars held different opinions regarding that. Some of them said it is for absolute disliking. They are Maaliki scholars. But some others said that it is for prohibition and they are the Hanbali and Thaahiri scholars. A third group said that it is prohibited in the little while disliked in the large quantities of it.
I view, Allaah Knows best, that prohibition is for forbidding in the little and large quantities of it. This also what the Hanbali scholars and those who follow them have adopted; however, the flowing water is excluded from that according to the consensus of the scholars and thus prohibition does not apply to it.
Sixthly, will the water in which it is urinated remain pure or become impure because of that urine?
Answer of that differs if the water is changed by impurity or not, and according to its littleness and plentifulness. If it is changed by impurity with a color, taste or smell, there are no different opinions among scholars regarding its impurity, whether it is little or in large amounts.
If it is not changed by impurity while it is in large amounts, also there is no disagreement among scholars on its purity. However, scholars have different opinions regarding determining the ruling of large amount.
If it is not changed while it is little, scholars have two opinions regarding that. First Opinion, it is impure and this is the opinion of some of the companions of the Prophet, peace and blessing be upon him, Thaahri and Maaliki scholars. They substantiated their opinion by the Hadeeth in which the Messenger of Allaah, peace and blessing be upon him, said: "Water is pure and nothing can make it impure." [Reported by Abu Daawood and At-Tirmithi deemed it Hasan (good) Hadeeth]
Sheykh Al-Islaam Ibn Taymiyyah adopted that opinion.
Second Opinion, it is what the majority of scholars have adopted that the little water becomes impure as soon as impurity reaches it, even if it is not changed for the apparent prohibition of that Hadeeth. However, what is correct, Allaah Knows best, is what the first group has adopted i.e. that water does not become impure unless its color, taste, or smell is changed, even if it is something disliked as it was pointed out previously.
Seventhly, some scholars deduced from that Hadeeth the prohibition of all things that attack and cause harm to others, or spoil their water, or make hateful for them their food. Actually, Islam is the religion of purity and cleanness.