A man who is impure on account of a running issue [as it says "If any man has a flow in his flesh..."¹], a menstruating woman [as it says "And if a woman flows, her flow being blood in her flesh... and if the flow of a woman's blood flows for many days..."²], and a woman who has given birth [as it says "If a woman conceives and gives birth..."³] are all sources of impurity. They make a utensil impure if they touch it, move it (even if it is earthenware), sit or lie on it (if it belongs to them and is fit for the purpose), or are covered by it, and they make a person impure if they touch him, move him, or are moved by him. Rabbinically, non-Jews are also sources of impurity in these ways.^a

The body fluids of such a person and blood from the womb are sources of impurity by touch or movement, as it says "His flow is impure",¹ and it says "And if the man with the flow spits on a pure man he shall wash his clothes and bathe in water and be impure until evening",⁴ and it says "And the unwell woman in her isolation and the man with his flow".⁵ A seat or bed that such a person has been on is also a source of impurity by touch or movement [as it says "And a man that touches his bed shall wash his clothes and bathe in water and be impure until evening... and anyone that touches anything that is under him shall be impure until evening; and one who carries them shall wash his clothes and bathe in water and be impure until evening... and anyone who touches her bed shall wash his clothes and and bathe in water and be impure until evening; and anyone who touches any utensil that she sits on shall wash his clothes and bathe in water and be impure until evening... and anyone who touches them shall be impure and shall wash his clothes and bathe in water and be impure until evening"⁶]. A man who has had sexual relations with such a woman is a source of impurity like her, except that his seat or bed [and body fluids], though impure, are not sources of impurity, as it says "[And if a man lies with her... he is impure for seven days] and any bed that he lies on becomes impure".^7,b

Such persons become pure when they have seven clean days (a total of fourteen days in the case of a woman who has given birth to a girl) and bathe [as it says "And if the man with the flow becomes pure from his flow he shall count seven days from his purification and wash his clothes and bathe his flesh in living water and be pure... and if she becomes pure from her flow she shall count seven days and afterwards become pure"⁸].^c

Sources:
1. Lev. 15:2ff	a. 1:1; 2:10; 6:1,3; 8:1-3; Kelim 24:7
2. Lev. 15:l9ff, 25ff	b. 1:8-9,12,14-15; 3:1-3; 6:2
3. Lev. 12:2,5	c. 5:1
4. Lev. 15:8
5. Lev. 15:23
6. Lev. 15:5,10,21-22,27
7. Lev. 15:24
8. Lev. 15:13,28