Tumah can be received in the following manners:
- By contact with dead body i.e. tumat met, which, in addition to the body itself, includes significant parts of a body, soil in which the body decomposed, and others.
- By coming in contact with certain dead animals, including most insects and all lizards (enumerated in Leviticus, Chapter 11, verses 29 - 32).
- By contact with certain bodily fluids i.e. niddah, zav/zavah (See Leviticus Chapter 15) 
- By giving birth to a child (the period of tumah is 7 days for a boy, followed by 33 days of taharah and 14 days for a girl followed by 66 days of taharah).
- By being present in a building or roofed structure containing a dead body. (tumat ohel)
- By contact with a primary source of tumah or an object that has been in contact with a primary source of tumah.
- By contracting tzaraat - see Leviticus chapters 13-14.
In the days of the Holy Temple, there were special sacrifices and ceremonies for purification from various types of tumah including the Red heifer ceremony for contact with the dead, and special ceremonies for tzarat and childbirth. Today, in the absence of a Holy Temple, the only purification method available involves washing or immersion in a mikvah. Thus today, all Jews are considered ritually impure, but Orthodox Jews and to a lesser extent, Conservative Jews still perform such purification rituals as are possible. The requirements for immersing in a mikvah are discussed in Tevilah.
Typically, one can remove oneself or one's items from being tamei by waiting a certain period of time and then immersing the tamei item in a mikvah. The tractates of Tohorot and book of Leviticus talk about tumah and taharah.
Tumah is to be contrasted with taharah, ritual purity.
- ↑ King James Version: Leviticus Chapt 11
- ↑ This view is held by Orthodox Judaism and remains a traditional view within Conservative Judaism. Although Conservative Judaism retains the concept of niddah and a prohibition on relations during the niddah period (including childbirth), recent decisions by the Committee on Jewish Law and Standards have endorsed multiple views about the concept of zavah, as well as the tumah status of a Niddah. The liberal view held that the concepts of tumah and tahrah are not relevant outside the context of a Holy Temple (and hence a Niddah cannot convey tumah today), found the concept of zavah no longer applicable, and permitted spouses to touch each other in a manner similar to siblings during the niddah period (while retaining a prohibition on sexual conduct). The traditional view retained the applicability of the concepts of tumah, taharah, and zavah, and retained a prohibition on all contact. See Niddah.
- ↑ Polyglot Bible: Leviticus: Leviticus 15