Rabbi Geoffrey W. Dennis, Water, (full text)

"The Spirit of God hovers over the waters (Gen. 1:2)." From this passage Jewish esoteric tradition derives the belief that water is a key component in invoking and encountering divine power and in other paranormal experiences. Water is the force of chaos and order only emerges as God drives back and delimits the watery abyss.

Separating the waters into heavenly and earthly zones then permits the cosmos to appear. With the appearance of dry land, God traps the primordial waters under the earth and seals them in place with the Foundation Stone on Zion. According to the Talmud, all the water of the universe is divided between the female tellurian waters and the male celestial waters. Their joining together fructifies the earth (P. Ber. 14a). There is a similar gender distinction made between rain and dew.

The kings of Israel can only be anointed standing over water. Studying Torah by a stream ensures that one's memorization will "flow like a river. (Horayot 12a)." According to Eccl. Rabbah 3:15, if one intends to use the Name of God for theurgic purposes, one should only do so over a body of water (also see Sefer Tagi).

Though God has tamed them, the waters still possess great and destructive power. Therefore, the appearance of supernal water while ascending through the palaces of heaven was considered a barrier and a danger to the living soul. (Chagigah 14b).
By the same token, water is a place of revelation (Ezek. 1:1; Dan. 10; Baruch III, I Enoch 13:7; Kohelet Rabbah 3.16). In the mystical book the Vision of Ezekiel, the prophet received his prophetic insights by gazing into the reflection on the river Chabar. Likewise, German Pietists would perform theurgic rituals over water (Sefer ha-Malbush). Among the Merkavah mystics, some rituals of drawing down angels required the summoner to be immersed neck-deep in living waters. Perhaps the image of the angel appears in the reflecting surface. Some Jewish divination techniques include studying the patterns of oil poured into a bowl of water.

Water sources are a favorite lurking place for spirits and demons (Lev. R. 24.3; Pesachim 112a), a belief that appears to be a hold-over from pagan traditions (The Banyas rapids at the headwaters of the Jordan are named for the Greek God Pan and the ruins of a shrine to him is still visible there).

Magical uses. Without question the water that has the greatest power is mayyim chayyim, "living water." This is rainwater that has not yet been drawn from its source by human hands or by artificial conduit. All seas, natural lakes, rivers, and ponds are reservoirs of living water. A source of living water is also the necessary ingredient in a mikvah, or ritual bath. The potency of living water derives from the fact that it has fallen directly from the pure state of heaven. As such, immersion in it has the power to purify that which it contacts. It also has heavenly energy, and for this reason it is used in rituals of power, such as constructing a golem, divination, ordeals, and the preparation of amulets.