Why does The Reliance of the Traveller highlight 216 liters of water in the context of impurities?

The Reliance of the Traveller, The Classic Manual of Islamic Sacred Law 'Umdat al-Salik, by Ahmad ibn Naqib al-Misri (translated by Nuh Ha Mim Keller) states:

e1.4 Impure means it is neither purifying nor pure. (O: Namely:

(1) less than 216 liters of water (qullatayn) which is contaminated by filth (najasa), even when none of the water's characteristics (n: i.e. taste, color, or odor) have changed;

(2) or 216 liters or more of water when one of its characteristics of taste, color, or odor have changed (n: through the effect of the filth. As for the purity of water that has been used to wash away filth, it is discussed below at e14.14).)

Here, "n:" indicates a "remark by the translator" and "O:" indicates an "excerpt from the commentary of Sheikh 'Umar Barakat".

This quantity 216 liters is mentioned many times (e1.7 through e1.16, e5.6, e9.1, e14.11, and probably more [I gave up enumerating]). It's a specific quantity, so it's reasonable to expect that it's derived from some Islamic source (and isn't just a best guess). I suspect it's equivalent to some less arbitrary quantity with another unit used during the time of the Prophet.

Question: Why does The Reliance of the Traveller highlight 216 liters of water in the context of impurities?

I also found it mentioned in a SeekersHub fatwa.

• Interestingly in this fatwa islamweb-Arabic they say that qullatayn is equal of about 160,5 liters, there are also statements saying it is 210 liters ahlalhadeeth. I guess you want to know that quantity of al-Qullah or the two qullah's (quallatyn). Mar 19, 2018 at 8:10
• If you take qullatayn as the volume of a 1.25 cubit cube where a cubit is about 48 cm, you get 216 litres. But I don't know how agreed-upon that calculation is. Mar 19, 2018 at 8:34

What is a qullah? First of all you should know that a qullah is basically a big vessel (search via google القلة). One could ask himself whether these vessels have been fabricated everywhere with the same volume....

The relatad ahadith about qullatayn (two qullahs) are linked in my answer on Levels of obligatoriness of rulings within schools of law. Here just one out of them to make clear what is meant:

"The Messenger of Allah (ﷺ) was asked about water and how some animals and carnivorous beasts might drink from it. He said: 'If the water is more than two Qullahs, it will not become filthy.'" (Sunan an-Nasa-i)

Qullah is a rather (slightly) varying measure as many other measures in the Arabic and Islamic world so you may find the quantity of one sa'a in Medina different than in 'Iraq etc. which makes things rather difficult.

So each estimation or calculation will depend on a certain definition.

216 l or 160.5 or ...

For example in (Arabic) fatwa #16107 on islamweb the answer relies on the information that two qullahs are equalt to 500 'Iraqi ratl which makes them equal to 160.5 l.

On ahlalhadeeth.com one post estimates one 'Iraqi ratl as equal to 406.25 g -> 500*406.25g = 203125 g or 203.125 kg -> 203.125 l

Just as a reference the Egyptian ratl is equal to 450 g

According to the book al-fiqh al-Muyassar الفقه الميسر one Qullah is equal to 93.075 sa'a which is equal to 160.5 l.

Some say al-Mudd is equal to 675 g and 0.688 l and is equalt 1.33 ratl ('Iraqi) in the view of a-Shafi'i and the scholars of al-Hijaz while the hanafi's consider 1 mudd = 2 ratl which means it is 3800 g.

as-Sa'a = 4 mudd is equal to 2176 g and 2.75 l (shafi'i view and the view of scholars of al-Hijaz) or 3800 g according the scholars of al-Iraq and the hanfis.

islamqa #154588 offers a measure of 1 qullah being equal to 102 kg according to sheikh Abudllah ibn Sulayman al-Manee' عبد الله بن سليمان المنيع based on the calculation: that one qullah is equal to 250 ratl and one ratl is 408 g

Feqh.web somebody has heard of the following equal measures: 161 l, 191 l, 206 l, 213 l and 306 l. all or most of these might have a background, but are hard to verify.

Maybe a good Conclusion