Rambam - 1 Chapter a Day

We already explained that there are only seven liquids that contract impurity and make foods susceptible to impurity. Other liquids are referred to as fruit juices and they neither contract impurity, nor make foods susceptible to impurity. The derivatives of the seven liquids that we mentioned are governed by the same laws as they are.

The derivatives of water are: fluids secreted by the eye, the ear, the nose, and the mouth, and human urine whether from adults or minors. Anything excreted by man is considered as a liquid whether it was excreted consciously or unconsciously. The urine of animals and salt that was liquefied are considered as fruit juices. They neither contract impurity, nor make substances susceptible to impurity.

The blood that is counted as a liquid is the blood that flows from a kosher domesticated or undomesticated animal or fowl at the end of its slaughter. Blood that flows at the beginning of the slaughter, by contrast, does not make food susceptible to ritual impurity, because the animal is still alive. It resembles the blood of a wound or blood that is let.

When a person slaughters an animal and its blood sputters on to food, but that blood is cleaned between the slitting of one of the signs and the other, there is a doubt concerning the matter. Therefore the ruling is held in abeyance. The food is neither eaten, nor is it burnt.

A derivative of blood is blood let by a human being that was released with the intent of it being drunk. If, however, it was released as a medical treatment, it is pure and it does not make foods susceptible to impurity. Similarly, the blood released during the slaughter of non-kosher domesticated or undomesticated animal or fowl, the blood that is released with mucous or with feces, or the blood of boils, blisters, and blood concentrated in flesh, all neither contract impurity, nor make substances susceptible to impurity. Instead, they are like other fruit juices.

The blood of a crawling animal is like its flesh, it imparts impurity, but does not make foods susceptible to impurity. There are no entities analogous to it.

Whey is considered like milk. Human milk that is not needed is not placed in the halachic category of a liquid. It does not make foods susceptible to impurity, nor does it contract impurity. Therefore, milk excreted by a male is not placed in the halachic category of a liquid. This also applies to the milk of a domesticated or undomesticated animal that was released without human intent, e.g., it flowed out from the animal's teats spontaneously or it was milked without intent. The milk of a woman, whether it was released intentionally or unintentionally, is generally placed in the halachic category of a liquid. It makes foods susceptible to impurity and it can contract impurity, because it is fit to be drunk by an infant.

Liquids released by those impure people whose impurity causes these liquids to be considered as a primary source of impurity, impart impurity even though the foods had not been made susceptible to ritual impurity beforehand. For the food's susceptibility to impurity and that impurity come simultaneously. They are: the secretion of a zav, his semen, and his urine, a revi'it of blood from a human corpse, and the blood of a nidah.

Similarly, the blood of the wound of a zav and others like him, the milk of such a woman, their tears and the other derivatives of water that they release impart impurity like impure liquids which impart impurity without any specific intent. For impure liquids impart impurity when they are brought into contact with food intentionally or when they come into contact unintentionally. Accordingly, if milk drips from the breast of a nidah or a zavah into the inner space of an oven, the oven and all its contents contract impurity.

We have already explained that the liquids released by a person who immersed that day do not impart impurity. Therefore, even if they fall on a loaf of bread that is terumah, it does not become susceptible to impurity unless they fall on it intentionally, as is the law regarding other pure liquids which do not make food susceptible to impurity unless they fall on it intentionally.

Sweat, pus or vomit, feces, the liquids released by a fetus born in the eighth month, the diarrhea of a person who drank the waters of the hot springs of Tiberias or the like, even if it is clear, are all not placed in the halachic category of liquids. They do not contract impurity, nor do they make foods susceptible to impurity.

When a person drinks other liquids and releases them, they are considered liquids as they were previously, for other liquids do not regain purity in a person's body.

What is implied? If one drank impure water and then regurgitated it, it is still impure. It did not become purified when released. If one drank impure water, immersed in a mikveh and then regurgitated it, or it became loathsome and then he regurgitated it, or it was released as urine, even if he did not immerse himself, it is pure.

If one drank other impure liquids or ate other impure foods, even though he immersed and then regurgitated them, they are still impure. They do not become purified in a person's body. If they became loathsome or were released as urine or as feces, they are pure.

We already explained that sweat is not placed in the halachic category of liquids. Even if a person drank impure liquids and excreted them by sweating, his sweat is pure. If, however, a person bathes in drawn water and then sweated, his sweat is impure. If he dried himself from the water and then sweated, his sweat is pure.

Moisture that collects on the walls of homes, trenches, caves, and cisterns is not placed in the halachic category of liquids. Even if the house is impure, the moisture that collects is pure. The moisture that collects in a bathhouse, by contrast, is considered as water. If water in the bathhouse was impure, the moisture that collects there is also impure. If one brought produce into such a house and moisture collects upon it, it becomes susceptible to impurity. If he brings containers there and moisture collects upon them, the moisture is considered as separated intentionally and it makes foods susceptible to impurity.

When there is a pool in a house and moisture collects on the walls of the house because of it, if the pool contains impure water, all the moisture that collects in the house because of it is impure.

When there are two pools in a house, one containing impure water and one containing pure water, if moisture collects close to the impure pool, it is impure. If it collects close to the pure one, it is pure. If it is equidistant from the two of them, it is impure.

The black liquid that flows from olives without their being pressed is considered like oil. The liquid that drips from the baskets of olives and grapes when they are harvested is not placed in the halachic category of liquids. It does not contract impurity, nor does it make foods susceptible to impurity unless it is collected in a container.

When a person weighs grapes in a weighing pan, the wine left in the weighing pan is not placed in the halachic category of liquids unless it is poured into a container. It resembles the liquid that drips from the baskets of olives and grapes mentioned in the previous halachah.

When a person pushes grapes that are terumah into a jug, even though the wine flows over his hands, everything is pure.

The liquids that flow in the butchering area in the Temple Courtyard, i.e., the blood of the sacrificial animals and the water used to clean them, are always considered as pure. They do not contract impurity, nor do they make foods susceptible to ritual impurity. This matter is a halachah conveyed by the Oral Tradition. Therefore all the blood of the sacrificial animals is not susceptible to ritual impurity, nor does it make foods susceptible to ritual impurity.

Since the blood of the sacrificial animals does not make food susceptible to ritual impurity, the sacrificial animals that were slaughtered in the Temple Courtyard were not made susceptible to ritual impurity through the blood of their slaughter. The meat of these sacrificial animals does not become susceptible to ritual impurity unless liquids other than those of the butchering area of the Temple come into contact with them.

When a cow that was consecrated as a sacrificial animal was made to cross a river and was then slaughtered while it still had tangible moisture on it, it has become susceptible to impurity. Therefore, if an impure pin was found in its flesh, the meat is impure.

Similarly, if the cow's mouth was sealed closed outside of Jerusalem, even though the status of the pin found in its meat is unknown, the meat is impure. The rationale is that it touched implements outside of Jerusalem. If the pin was found in its wastes, the meat is pure. In either instance, the hands of the people involved in cutting up the animal are pure, because the decree involving the impurity of hands does not apply in the Temple, as we explained. In which context does the above apply? For the meat to be considered impure according to Scriptural Law. To incur impurity of Rabbinic origin, by contrast, consecrated food does not require exposure to liquids to make it susceptible to ritual impurity. Instead, the cherished nature of consecrated foods itself makes the meat susceptible to impurity. If any impurity, whether minor or severe, touches it, it becomes disqualified, even though it was not exposed to liquids, as we explained.