Photo Credit: Tzvi Jacobs

Rabbi Fishel Jacobs of Kfar Chabad in Israel believes the Jewish world is experiencing a “family purity revolution.” He should know. Since 1998, Rabbi Jacobs has published five books on the laws of family purity. Today, he serves as a halachic advisor to four different websites, all designed to help women keep the mitzvah more accurately.

“The landscape is changing,” he told The Jewish Press. “Twenty years ago, there was no compendium of laws and no calendar, nothing concise and practical for calculating vestot (halachically significant times in a woman’s cycle).” Rabbi Jacobs created the first calendar to help women do just that. He spent several years and thousands of dollars developing a practical format that was halachically accurate.


First published in Hebrew under the title Zemonim, this paper calendar has been reprinted and distributed every year for the past 20 years. “The first year, there was a Chabad women’s convention and they bought 500 copies of the pamphlet. Tens of thousands of copies have been distributed since. Zemonim includes a summary of the laws. That’s the most important part,” Rabbi Jacobs said. An alternate version for non-Chabad women is available.

Following the success of Zemonim, Rabbi Jacobs published Chochmot Hatahara in Hebrew, a commentary of the subject intended for advanced Torah students and poskim. His most popular publication is Family Purity – A Guide To Marital Fulfillment, which has been revised eight times since its initial publication. It is packaged with a study guide and a 10-year Zemonim-style calendar in English.

His prolific work in the field of family purity started with yechidus (a private meeting) with the Lubavitcher Rebbe in 1981. Jacobs recorded and transcribed the meeting, in which he was told to become a rabbi. At the Rebbe’s insistence, he stayed in kollel for 13 years. Despite failing the examination for semicha three times, he was eventually ordained by Rav Mordechai Eliyahu and Rav Avraham Shapira, the two chief rabbis of Israel at the time. This was something no American had ever accomplished.

After being ordained, Rabbi Jacobs started teaching chassanim in Kfar Chabad. “Twenty years ago,” he commented, “people weren’t keeping [these laws] accurately. It was like the Wild West. People were missing things.” Today, he said, “It’s a whole different ballgame.” There are websites and smart phone apps to help. “Nowadays, [the mitzvah] is being kept more precisely.”

Rabbi Elazar and Rivkah Bloom

Rivkah Bloom, who earned a masters degree in engineering and computer science from MIT, is behind two of the new generation of tools designed to help women observe the mitzvah. is a rabbinically-approved website with companion smartphone apps. It calculates relevant times and dates according to Chabad, Ashkenazi and Sefardi custom. The site sends users reminders by email and text and has an Ask The Rabbi feature, to which Rabbi Jacobs responds. New elements, such as a mikvah preparation list, are being implemented at the request of users.

In addition to his involvement with, Rabbi Jacobs consults on three similar websites, including a new site that has “expansive aspirations to spread outside the frum community.” He serves as a halachic advisor to these sites and also answers hundreds of questions from users all over the world.

Bloom’s most ambitious project is the Tahor app, which allows women to send a photo of questionable stains to a rabbi for anonymous checking. The color calibration algorithm was developed by David Silver, a color computer vision engineer specialist from the Technion in Israel. Originally released for iPhone users, Tahor is now available on select Android phones.

Bloom told The Jewish Press, “More rabbonim and roshei yeshivos are encouraging us to continue pushing forward. They recognize that Tahor is a ’triage’ app. It allows the rabbi to assess whether the [cloth] must be shown to a rabbi or is easy enough to answer within the app.” She likens the use of Tahor to tele-medicine where, “the doctor can view a mole and determine whether the patient needs to be seen by a doctor or can easily be diagnosed over an app.”

Evidence points to the fact that the Tahor app is helping women keep the mitzvah. Bloom said, “Since Tahor launched, it has been downloaded in over 62 countries, many of which do not have rabbonim who are accessible and can answer taharat hamishpacha questions. Tahor is also being used by many kiruv rabbonim who are assisting women new to taharat hamishpacha.”

As amazing as these advances are, Rabbi Jacobs doesn’t see them as tools for spreading the wisdom of family purity. “They are all still focusing on people who are already observant. Even using the platforms that exist, we as a Jewish people would be much better if the sites would be adapted to be more outreach. The existing platforms are still focused toward a group that’s already involved. That’s only 2-5% of Jews. I would like to see what we have be more inclusive.”

Rabbi Jacobs sees the merger of technology and family purity as being ripe for development “to bring these laws to the attention of a wider audience in a loving way. People want to have good marriages. We need to push this wisdom out further.”

Bloom sees it slightly differently. “Many people involved in kiruv have reached out to me and explained that these apps are helping to lower the ‘barrier to entry’ for couples who are interested in observing the laws.

“The women they teach often express interest in keeping taharat hamishpacha, but are not yet comfortable enough to personally ask a rabbi questions that pertain to private and personal experiences. When presented with the Tahor app, there has been a tremendously positive response, as these women appreciate the anonymous platform Tahor offers, alleviating the initial discomfort many of these women experience when new to this mitzvah.

“Since inception, the goal of and the Tahor app has been and continues to be to offer all women the opportunity to involve themselves in, and increase their observance of, this mitzvah. I have found that women, regardless of their level of religious commitment, are embracing these apps as a way to connect to and enhance this crucial part of their heritage.”

Along with these technological advances, Rabbi Jacobs highlighted the work of Merkoz Hatahara, an organization that provides support for family purity among non-religious women in Israel. Merkoz Hatahara has “female emissaries in every city. They have a database of tens of thousands of women. The emissaries have personal contact, though texts and emails, on a monthly basis, to give the women support and encouragement. They escort them through the entire cycle. They set up a huge network under the Admur M’Linsk from Beni Brak and they are very successful.”

Could such a thing work in America? Rabbi Jacobs said, “This organization is 100% devoted to family purity. Who would do it in America? I hope someone does it!

“My family purity writing and answering questions is based in my personal love for the family unit and my deciding to strengthen it. I believe in family. I believe in marriage. That’s one of my missions in life. Nothing would make me happier in this world than to see more Jewish people throughout the world becoming attached to the family purity laws. It’s just that simple.” Rabbi Jacobs concluded.

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