Mutahhirat i.e., the things which make a najis thing clean. These are 12 in number:
(1) Water; (2) Earth; (3) Sun; (4) Istihala; (5) Intiqal; (6) Islam; (7) Taba’iyat: (8) Istibra;
(9) Ghaybah (disappearance) of a Muslim; (10) Zawal al-‘Ayn; (11) Inqilab and (12) Flowing of blood in normal quantity from a lawfully slaughtered animal.
(a) According to purity or impurity, water is of two kinds: mutlaq i.e., pure water; and mudaf i.e., mixed water. Mixed water cannot make anything clean. Instead, it itself becomes unclean by coming into contact with anything unclean.
(b) Mutlaq is of 5 kinds: (1) Rain water; (2) Running water; (3) Well water; (4) Still water about a kur or more than a kur; (5) Still water less than a kur.
Water cleanses a najis thing on condition that the water is (1) Mutlaq and (2) Clean (tahir), and (3) Does not become mudaf by coming into contact with that najasah, and (4) All the najasah is washed away from that najis thing.
Rain water, running water (like sea, river, stream, spring etc.) and well water make things clean if washed once after removing the najasah. But if anything becomes najis by urine it must be washed twice. It is better to wash it twice even in other najasah.
Clothes should be squeezed after every washing as described above.
Still water which is just a kur or more than a kur, also makes things clean in the same way.
These waters cannot be unclean by mere contact with najasah. They will be unclean if either their taste, color or smell is changed by that contact.
Kur means water which takes 27 cubic span space (3x3x3). It is better to make it 42 7/8 cubic span (3 1/2 x 3 1/2 x 31/2). 1 span = 9 in.
Still water which is less than a kur becomes unclean by just coming into contact with a najasah. To cleanse with clean still water, it is necessary to wash twice after removing the najasah, and it is better to wash thrice.
The water running from the pipes in the houses is treated as river water so long as it is running.
Pots must be cleansed three times with the water which is less than a kur, and once if it is washed in kur or running water.
If a pig licks the pot, then it should be washed seven times whether the water is running or kur or less than that.
The same is the rule if a rat dies in a pot.
If a dog licks the pot, it should be rubbed with wet clean earth thoroughly; then, after washing away the earth, it should be washed twice with the water which is less than a kur, or once in kur or running water.
If a pot becomes najis by liquor, it must be washed three times, whatever the kind of water.
The earth makes clean the sole of the shoe or feet. But there are 4 conditions for it:
1. The najasah must have been contacted from walking on the earth;
2. It is removed by walking on the earth;
3. The earth is clean;
4. And dry.
Note: This rule does not apply to the end of the stick or wheels of car or carts, etc.
The sun makes clean those things which cannot be moved like wall, tree, earth etc. If the najasah is removed, and the place or tree etc. is wet, and then it becomes dry by the direct rays of the sun, it becomes clean. If it dries by hot air combined with the sun's rays, or just by hot air, or by sun's heat without direct rays, it will not be clean.
It means "change". If a najis thing is changed into a clean thing (chemically), it will become clean. For example, if a dog after death is changed into earth, that earth will be clean.
It is similar to the istihala. The difference is that in istihala, the shape and form, all are changed, while in inqilab, only the properties are changed, but the shape is not entirely changed. Its only example: If wine becomes vinegar, it is inqilab. By inqilab, it will become clean.
Note: If grape-juice is fermented, either by fire or by itself, it is haraam (unlawful) to drink. But if that fermented liquid is boiled on fire and its two-thirds are evaporated… the remaining one-third will become halal.
It means to change place. If a mosquito sucks the blood of a man and there is a gap of time, so that the blood is called the blood of mosquito, it will become clean.
A Kafir becomes clean after accepting Islam.