On Sunday, Lisa Hamburger immersed a terra cotta ceramic bowl in San Francisco's community mikveh. Now she will use it to thaw frozen sperm for her scheduled impregnation.

Also at the mikveh, Michelle Binder dunked a plastic coffee mug, her first personal possession after leaving a halfway house and, before that, dope-filled streets.

Wedged in a bucket among kiddush cups, candleholders and other ritual vessels, the bowl and mug were lowered into a placid pool at Mikvah Israel B'nai David in a lay-led ceremony by members of Congregation Sha'ar Zahav, a San Francisco Reform synagogue with a largely gay constituency.

The 15 worshippers visited the Sacramento Street facility as part of a synagogue program to explore the Jewish practice of spiritual cleansing and renewal in water. They are among a growing number of non-Orthodox Jews who, like Sha'ar Zahav's Jhos Singer, have discovered — "It's hip to dip."

Renee Weinreb, vice president of the Mikveh Society of San Francisco, talked to the group about halachic tradition, which focuses on the ritual immersion of an Orthodox woman after niddah, the approximately 12-day period during and following menstruation in which a woman is considered ritually impure. The couple cannot resume sexual relations until the woman ritually cleanses herself by immersing in the mikveh.

Though not mandated by halachah, some men use the mikveh for renewal before Shabbat or Yom Kippur. And rabbis use it for conversion and adoption ceremonies.

So important is the mikveh to Judaism, Weinreb explained, "that it was all right to sell a Torah scroll in order to start a mikveh. Even when the Jews were under siege at Masada, there was mikveh," fed by rainwater.

The San Francisco mikveh also is fed by rainwater that flows into a deep, square pool the size of a playground hopscotch game. The humid room is lined floor-to-ceiling with shiny blue tiles and natural wood.

The Sha'ar Zahav group had come to the mikveh with rituals of their own in mind. They would immerse household containers in the spirit of Moses, who commanded the Israelite warriors to decontaminate themselves, their animal-skins and other wooden vessels after warring with the Midianites.

Lying on the edge of the pool, congregant William Gersten dipped the vessels beneath the water's surface as the group sang a blessing: "Baruch Atah Adonai Eloheinu Melech Haolam, asher kidshanu b'mitzvotav v'tzivanu al hatvilah kilim." (Blessed are You, Lord our God, Ruler of the universe, Who has sanctified us with His commandments and commanded us concerning the immersion of vessels.)

Singer led the group in Chassidic-style niggunim, or wordless melodies, and gave a sermon on the kabbalistic concept of vessels as symbolic of the human body that holds the soul.

"If you drink with [the vessels], from here on out, you should be able to taste" something special, Singer said. "If you wash with it, you will wash with a touch of mikveh. It will hold a micro-droplet of HaShem" [God].

Many in the group would return to the mikveh alone before Yom Kippur to immerse themselves and prepare for atonement.

Eight months pregnant, Singer planned to visit the mikveh with her partner, who also is pregnant. One after the other, they will immerse and pray for healthy, full-term babies.

Singer noted that a wide variety of mikveh rituals have become popular among some non-Orthodox Jews who once rejected the rite but now find new meaning in it.

"It's not like jumping into a pool or hot tub. You are in a heightened state, your mind focused on renewal, your body relieved of gravity; the water is bathing your soul," she said.

Some Northern California rabbis have promoted immersion in natural bodies of water, like secluded beaches and mountain lakes, as well as in the mikveh. And Rabbi Amy Eilberg, a Conservative rabbi and leader in the Jewish healing movement, cites an increase of mikveh use among those who have overcome illness or who face life-threatening disease. The immersion, she said, can bring hope to the new phase of life.

Michelle Binder says that's one of the reasons why she chose her trusty travel mug for dipping last Sunday.

"It's the kind of thing that wakes me up. It's part of my new beginnings" after graduating from drug rehab.

And Lisa Hamburger plans one more dunk before she is artificially inseminated in November. She will immerse herself at Ocean Beach by moonlight in the days between her next niddah and next month's hopefully fruitful ovulation.