What is a mikveh?  How is the water acquired for the mikveh?  Some
mikvehs have a divided stairway.  Why is it divided?  When and why was
a mikveh used?  Mikvehs are still used today by orthodox Jews.  When
are they used?

Hello ciao! 

Thanks, once again, for furthering my learning about Jewish culture.
:-)

I'll respond to your questions separately. 


What is a mikveh? 
*****************

A mikveh is a body of water used by Jewish women for ritual cleansing
immersion about twelve days after the commencement of her menstrual
period. The following resources give more details.

Sex and Purity: What is a "mikveh"?
URL: http://www.faqs.org/faqs/judaism/FAQ/05-Worship/section-46.html
Quote: "A mikva or mikveh is a place used for ritual immersions. A
proper mikva contains a minimum of 40 SE'AH--about 191 U.S. gallons
(Sorry, but you'll have to do your own metric conversion.) of undrawn
water. In general, if there are more than 40 SE'AH, then the remainder
of the water may come from any source...."Undrawn" means not filled by
bucket or by metal pipes....Natural lakes, whether or not fed by
streams or rivers, fall into the category of "undrawn waters." Many
synagogues also provide indoor mikvas."

ENTERING THE MIKVEH 
URL: http://www.uahc.org/rjmag/396js.html
Quote: "What I knew about the mikveh I had learned from books. In a
nutshell, they said Jewish tradition requires a couple to abstain from
sex for about twelve days beginning at the start of the woman's
period; she then immerses in the "living waters" of the mikveh - a
manifestation or symbol of God's presence - after which she and her
husband can be intimate again."


How is the water acquired for the mikveh?  
*****************************************

As seen above, the general rule is that the mikveh must contain at
least 191 U.S. gallons of "undrawn" water, or water not acquired
through the use of buckets or pipes. This means that rivers, lakes, or
oceans would be acceptable for a mikveh. For man-made mikvehs, the
water typically comes from a natural spring or from collected
rainwater.

Mikveh Ramat Shalom 
URL: http://www.iida.org/comp/mikveh.html
Quote: "It can be only performed in fresh spring water, or in a
specially dedicated place fed by rain water which has to be collected,
stored and communicated to the bath recipient which is called the
Mikveh."

Coming of Age: The Growth of the Conservative Mikveh Movement
URL: http://www.uscj.org/item15_660_666.html
Quote: "A mikveh involves at least two containers: the bor, or
collecting container, and one or more adjacent pools for immersion.
Water must be collected on mikveh premises from rain or snow runoff,
not drawn or transported.  Dry places, such as Las Vegas, use melted
ice to fill the bor. Through a tube, a small amount of  'living water'
collected from rainwater or melted ice is allowed to mix (a process
known as 'kissing') with the filtered, warmed, chlorinated water in
the immersion pool."


Some mikvehs have a divided stairway.  Why is it divided? 
*********************************************************

The stairway in a mikveh is divided so that the bather can go down one
side "impure" and come back up the other side "purified". Basically,
they don't need to walk in their impure steps on the way out.

Fifty Years of the Dead Sea Scrolls 
URL: http://www.lehrhaus.org/online/scrolls/scrolls_4.html
Quote: "So what about the plaster dividing lines on the stairs? The
bather would go down one side of the stairs ritually impure. Having
completely immersed and purified himself, he would have to go up the
other side of the stair dividing line, since his feet were impure on
the side going down."
 
How Did They Use Water at this Desert Site?
URL: http://www-relg-studies.scu.edu/facstaff/murphy/courses/sctr108/archaeology/04-water.htm
Quote: "They have more elaborate staircases, sometimes with one or two
vertical dividers to separate those who are ritually impure coming
into the bath from those who are ritually pure coming out of the
bath."

A picture of an ancient mikveh stairway can be found at:
http://www.messianictimes.com/article_detail_arc.asp?article=551&issue=11-4


When and why was a mikveh used? 
*******************************

As stated above, a mikveh is used (by both men and women, but more
commonly by women) for ritual cleansing purposes. The following
resources explain further.

Coming of Age: The Growth of the Conservative Mikveh Movement
URL: http://www.uscj.org/item15_660_666.html
Quote: "According to the Bible, immersion is required both for married
women after menstruation and for men after nocturnal
emissions....Traditionally observant men immerse before Shabbat and
holidays, and scribes go to mikveh before writing a Torah scroll, as
do members of the hevra kadisha (burial society) after preparing a
corpse for burial."

The Shivah Neki'im
URL: http://www.yoatzot.org/article/39
Quote: "A niddah who wishes to return to a state of taharah (ritual
purity) must first perform a hefsek taharah to ascertain that all
bleeding has ceased. She must then ascertain for the following seven
days that bleeding has not recurred, before she may immerse in the
mikveh. These days are known as the shivah neki'im, which is literally
translated as "seven clean days." Since the status of niddah has
nothing to do with being dirty, "seven blood-free days" may be a
better translation. A woman during this time period is said to be
"counting the shivah neki'im," even though she is not obligated to
actually enumerate each day."


Mikvehs are still used today by orthodox Jews.  When are they used?
*******************************************************************

This seems to be a bit of a repeat from the previous question, but
I'll use this opportunity to introduce some of the less "technical"
reasoning behind the mikveh. The following website has some of the
best explanations of the hows, whens and whys behind this practice.

Kosher Sex - Niddah:  The Laws of Separation
URL: http://www.mechon-mamre.org/jewfaq/sex.htm
Quotes: 

"One of the most mysterious areas of Jewish sexual practices is the
law of niddah, separation of husband and wife during the woman's
menstrual period.  These laws are also known as taharat ha-mishpachah,
family purity.  Few people outside of the Orthodox community are even
aware that these laws exist, which is unfortunate, because these laws
provide many undeniable benefits"

"According to the Torah, a man is forbidden from having sexual
intercourse with a niddah, that is, a menstruating woman.  The law of
niddah is the only law of ritual purity that continues to be observed
today."

"The time of separation begins at the first sign of blood and ends in
the evening after the woman's seventh "clean day".  This separation
lasts about 12 to 14 days.  The rabbis broadened this prohibition,
providing that a man may not even touch his wife during this time."

"The Torah does not specify the reason for the laws of niddah, but
this period of abstention has both physical and psychological
benefits."

"The fertility benefits of this practice are obvious and undeniable. 
In fact, it is remarkable how closely these laws parallel the advice
given by medical professionals today.  When couples are having trouble
conceiving, modern medical professionals routinely advise them to
abstain from sex during the two weeks around a woman's period (to
increase the man's sperm count at a time when conception is not
possible), and to have sex on alternate nights during the remaining
two weeks.  When you combine this basic physical benefit with the
psychological benefit of believing that you are fulfilling God's will,
it is absolutely shocking that more couples with fertility problems do
not attempt this practice.  The rejection of this practice by the
liberal movements of Judaism is not a matter of 'informed choice', but
simply a matter of ignorance or blind prejudice."

"In addition, women who have sexual intercourse during their menstrual
period are more vulnerable to a variety of vaginal infections, as well
as increased risk of cervical cancer."

"But the benefits that the rabbis have always emphasized are the
psychological ones, not the physical ones.  The rabbis noted that a
two-week period of abstention every month forces a couple to build a
non-sexual bond as well as a sexual one.  It helps to build the
couple's desire for one another, making intercourse in the remaining
two weeks more special.  It also gives both partners a chance to rest,
without feeling sexually inadequate.  They also emphasized the value
of self-discipline in a drive as fundamental as the sexual drive."


I hope this information is of help to you.   
  
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websearcher-ga              
              
      
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The mikveh is used today by Orthodox, Conservative and Reform Jews. 
It is commonly used when a person converts to Judaism, as immersion is
an important requirement in the process. Interestingly, many American
Jews have never visited a mikveh and some Jews even frown upon it's
use.

The water in the mikveh is extremely soft.  So soft is the water,that
extreme relaxation is imposed upon the body as soon as immersion has
taken place. In some respects, I would suppose that immersion in a
mikveh is similar to the suspension effect experienced by a fetus,
while in utero in amniotic fluid.

One more comment:

Some Jews visit a mikveh once a week, other Jews never visit a mikveh.
 The price per visit in the mikveh, if you don't have a membership for
it's use, will cost about $100/visit.

Addition comment:

Prior to the use of a mikveh, a person must be very clean.  Thus, they
must shower, wash their hair, and be sure their finger and toe nails
are clean. No jewelry is allowed and as a matter of fact nothing
should be placed between the mikveh waters and a person's body.

It's been my experience that more men, than women actually visit a
mikveh.

It is common for a Jewish woman to visit a mikveh just prior to her
marriage, as a purification ritual.

As an Orthodox rabbi, I found websearcher-ga's information to be
pretty good.  Although you'll find a lot more information if you
search Google using the spelling "mikvah," which is based on Hebrew. 
(The spelling "mikveh" is based on Yiddish.)

One important omission: There is no group of Jews today, even the most
fervent Orthodox, that follows Biblical law literally.  This is
because Jewish law is traditionally based on the Oral Torah (and the
way it interprets the Written Torah).  In this case, it's important to
note that the requirement for men to immerse after a nocturnal
emission was created by the rabbis, and later annulled by the rabbis. 
Although later CUSTOMS developed for men to immerse --before Yom
Kippur (the strongest such custom), and/or before the other major
holidays, and/or every Friday, and/or every day, remember that these
are only customs and vary widely within Orthodox circles.

In contrast, women's monthly immersion after menstruation is
considered by the Oral Torah to be a LAW, and not just a minor law,
but one of the most severe laws even among the Biblical ones. This is
why the mikvah is and always has been a major part of Orthodox Jewish
life.  For details on how-to, see http://www.yoatzot.org/category/24

By the way, the divided stairway may have been popular thousands of
years ago, but not today.

Some of the information posted here by researcher-ga, however, is not
reliable.  The price is not "$100/visit" but varies with every single
mikvah.  The more people in an area use a mikvah, the less it will
charge per use.  The statement that "It's been my experience that more
men, than women actually visit a mikveh" is misleading, since all it
says is that researcher-ga's experience is with people who do not
follow Jewish law but rather decide whether to immerse based on their
own feelings.  The comment that "some Jews even frown upon it's use"
is as irrelevant as saying that some Jews don't believe in God; it may
be correct, but it tells you nothing about Judaism!