Can You Do Wudu with Water Mixed with Pure Substance?
Question

What is the ruling on water that has been mixed with some pure substance: is it permissible to do Wudu and Ghusl with it?
Praise be to Allah.If some pure substance is mixed with pure water deliberately, then there are three scenarios:

First scenario:

If water that is pure is mixed with some pure substance , and its colour, taste and smell does not change, then it remains pure and purifying, because it is still called water.
Ibn Qudamah (may Allah have mercy on him) said: “We do not know of any difference of opinion among the scholars concerning the permissibility of doing Wudu with water that is mixed with a pure substance that has not changed it.” (Al-Mughni, 1/25)
If a small amount of herbs, hummus, flowers, saffron and the like falls into water, and leaves no taste, colour or smell, it is permissible to purify oneself with that water.
Similarly, if such things change the water only slightly, that does not matter.
This is indicated by the Hadith of Umm Hani’ (may Allah be pleased with her), that the Messenger of Allah (blessings and peace of Allah be upon him) and Maymunah did Ghusl from a single vessel, a large bowl in which there were traces of dough. (Narrated by An-Nasa’i, 240; classed as authentic by An-Nawawi in Khulasat Al-Ahkam, 1/67, and by Al-Albani in Al-Irwa’, 27)
At-Tibi (may Allah have mercy on him) said: “What appears to be the case is that the traces of dough in that large bowl were not great.” (Mirqat Al-Mafatih, 2/457)
An-Nawawi (may Allah have mercy on him) said: “If it is a small amount, such as if a small amount of saffron fell in it and it turned slightly yellow, or soap or flour fell in it and the water turned slightly white, such that it could not be called by a name other than water, then the correct view is that it is still pure and purifying, because the name remains the same.” (Al-Majmu` Sharh Al-Muhadhdhab, 1/103) What is meant is that it is still called water.
Imam Ahmad (may Allah have mercy on him) said: “If the water that is mixed with something is not called after that thing and is still called water, then there is nothing wrong with it.” (Al-Intisar fil-Masa’il Al-Kibar by Abu Al-Khattab Al-Kalwadhani (1/122)

The second scenario:

If pure water is mixed with a pure substance , so that it is no longer called water.
It is not valid to do Wudu or Ghusl with this [altered] water, according to scholarly consensus, such as if tea leaves are added to water, and changes its colour and taste, so that it is no longer called water, and is rather called tea, or if meat is cooked in water, and this water changes and becomes broth. It is not permissible to do Wudu with it.
Ibn Qudamah (may Allah have mercy on him) said: “With regard to water that is mixed with something pure to the extent that its name changes and that thing overwhelms the water, so that it is now called dye or ink or vinegar or broth, and so on, and what is cooked in it is pure, so it changes as a result, such as water in which herbs are boiled –  with regard to all of these types, it is not permissible to do Wudu or Ghusl with it, and we do not know of any difference of scholarly opinion concerning that.” (Al-Mughni, 1/20)
Imam Ahmad (may Allah have mercy on him) said: “Do not do Wudu with anything that is no longer called water.” (Al-Intisar fil Masa’il Al-Kibar by Abu Al-Khattab Al-Kalwadhani, 1/122)

The third scenario:

If ordinary water is changed with the addition of any pure substance, but it is still called water – such as water that is mixed with soap and its colour changes, or hummus falls into water and changes its taste, or saffron falls into water and changes its fragrance, but it is still called water – there is a difference of scholarly opinion as to whether it can be used for purification.
The majority of scholars are of the view that water that has been changed by being mixed with pure substances is pure water but cannot be used for purification, because it is no longer called water in the ordinary sense, so it cannot be called water in an unqualified sense. (See: Al-Mughni, 1/21; Al-Kafi by Ibn `Abd Al-Barr, 1/155; Al-Majmoo`, 1/103)
The view of Imam Abu Hanifah (may Allah have mercy on him), and one view narrated from Imam Ahmad (may Allah have mercy on him), is that it is pure (Tahir) water and can be used for purification, because it is still water. This is also the view of Ibn Hazm, and was favoured by Ibn Al-Mundhir and Shaykh Al-Islam Ibn Taymiyah, and – among contemporary scholars – the Permanent Committee, Shaykh Ibn Baz and Shaykh Ibn `Uthaymin (may Allah have mercy on them).
Ibn Hazm (may Allah have mercy on him) said: “With regard to any water that is mixed with something pure and permissible, and the colour, smell or taste of that thing appears in the water, but it is still called water, it is permissible to do Wudu with it, and according to the Hanbalis it is permissible to do Ghusl for Janabah with it, whether what fell into it was musk, honey, saffron, or anything else.” (Al-Muhalla, 1/200)
The reason for the difference of opinion was that the scholars agreed that it is permissible to purify oneself with water, without further qualification, but it is not permissible to do it with water that is further qualified, such as rosewater, vinegar water and so on.
As for water that is mixed with pure substances and changes as a result, that is a matter which falls in between the two categories mentioned above.
Ibn Qudamah (may Allah have mercy on him) said: 
“A number of Ahmad’s companions narrated from him the view that it is permissible to do Wudu with it, and this is the view of Abu Hanifah and his companions, because Allah, may He be Exalted, says (interpretation of the meaning): “And if you … find no water, then seek clean earth and wipe over your faces and your hands [with it]” [an-Nisaa’ 4:43]. This verse is general in meaning and applies to all kinds of water, because the word Ma’ [water] appears in the indefinite form in the context of negation, which in Arabic is general in meaning, so it is not permissible to do Tayammum [dry ablution, wiping over the face and hands as mentioned in the verse] when such water is available… and this person can find water.
Also, the Prophet (blessings and peace of Allah be upon him) and his companions used to travel, and most of their water skins were made of leather, which usually changes the water, but there is no report from them to indicate that they did Tayammum when that water was available. Moreover, it is pure and purifying, and is mixed with something pure, which did not take away from it the name of water, or the softness or fluidity of water.” (Al-Mughni, 1/21)
Shaykh Al-Islam Ibn Taymiyah (may Allah have mercy on him) said: “So long as it is still called water, and is not overwhelmed by another substance, it is pure and purifying, and may be used for purification, as is the view of Abu Hanifah and of Ahmad according to the other report from him. This is what was stated in many of [Ahmad’s] answers.
This view is the correct one, because Allah, may He be Glorified and Exalted, says (interpretation of the meaning):
“And if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and find no water, then seek clean earth and wipe over your faces and your hands [with it]” [An-Nisa’ 4:43]
The phrase “And if you … find no water” is indefinite in the context of negation, so [it is general in meaning and] applies to any water; there is no differentiation between one type and another.” (Majmu` Al-Fatawa, 21/26)
Then he (may Allah have mercy on him) said: “Moreover, it is proven that the Prophet (blessings and peace of Allah be upon him) instructed that the pilgrim in Ihram [who died during Hajj] be washed with water and lotus leaves, and he instructed that his daughter [after she died] be washed with water and lotus leaves, and he instructed that the one who becomes Muslim should do Ghusl with water and lotus leaves. It is well-known that lotus leaves inevitably change the water, and if this change spoiled the water [i.e., made it invalid to use it for purification] he would not have given instructions to do that.” (Majmu` Al-Fatawa, 21/26)
Shaykh Ibn Baz (may Allah have mercy on him) was asked: Chlorine is added to drinking water, and it is a substance that changes the colour and taste of the water. Does this affect the validity of Wudu?
He (may Allah have mercy on him) replied: 
“Changing water by adding pure substances and treatments that are added to water to prevent harm to people – provided that the water is still called water – does not matter, even though some changes occur as a result of that.” (Fatawa Ash-Shaykh Ibn Baz, 19/10)
And Allah knows best.