Judaism is unique in its focus on achieving holiness. There are differing definitions for “holiness,” dependent on time (e.g., Sabbath), place (e.g., the Temple Mount in Jerusalem, a synagogue*), or person (e.g., prophets, sages). The first step to achieving holiness is maintaining a state of “taharah,” a spiritually pure status that allows a person to enter into holy places and participate in sacred activities.
Water is an important conduit to achieving “taharah” (purity). A person looking to be cleansed from an impure spiritual status (called “toomah”) immerses completely in water in a specifically designed “mikveh.” This applies to Jewish men, Jewish women, and those who are converting to Judaism.**
In the language of the Kabbalah (Jewish mysticism), “water” alludes to acts of kindness. One who engages in acts of kindness all the time has taken an important step closer to achieving the exalted status of “being holy.”
* Anyone can enter a synagogue - its “holy status” is due to the fact that holy activities such as prayer and study take place there. It has a different dimension of holiness than the Temple Mount.
** The mikveh turns non-Jews into Jews, completing the conversion process. It enables them to participate in a Jewish life from which non-Jews are exempt.