Mikveh Water Project Brings Together Religion, Science and Environment

A pilot project to recycle gray water gathered from the showers at a mikveh (ritual bath) in Jerusalem could someday lead to a nationwide program that conserves anywhere from 6.6 billion to 13.2 billion gallons of water per year in Israel alone.

Dr. Eran Friedler of the Technion-Israel institute of Technology Faculty of Civil and Environmental Engineering an expert on gray water recycling first became involved in the trailblazing mikveh project at the request of “Shomera for a Better Environment,” an environmental organization known for its innovative initiatives in advocacy, resource management, education and community outreach.  With the enthusiastic backing of the Division of Water Conservation of the Water Authority and approval from Israel’s Ministry of Health, the pilot program is slated to begin sometime over the next few months.

“This unique collaboration of so many different sectors could lead to a great contribution to saving water in Israel.  It will provide a lot of information not available today and a wealth of real-world experience,” said Shomera executive director Miriam Garmaise.

Typical mikveh

According to Friedler, the majority of the gray water generated by mikvehs comes from the showers people use prior to using the mikveh.  This shower runoff contains a long list of contaminants, including soap, shampoo, organic matter, dirt, skin, and pathogens all of which must be removed to treat and purify the water before it can be re-used to avoid environmental and health problems from occurring. In order to do so, Friedler plans to employ two distinct technologies, one that is “extensive” and one that is “intensive.” Haifa-based Water Arc, a company specializing in water use efficiency and in water reuse in the urban/residential sector, has been selected to design and implement these technologies.

The extensive method will entail the use of constructed wetlands, which are in essence artificial marshes or swamps.  Like the natural wetlands they are modeled after, they contain porous media that act as biofilters, removing sediments and pollutants from the shower and gray water being run through them.

The intensive method will be a membrane bioreactor (MBR).  This complicated and efficient system biologically removes organic matter, and features a membrane that filters and traps harmful bacteria and other pathogens while allowing water and other safe materials through.

At the beginning of the program, the recycled water will be tested, and then flushed away.  Only when consistently successful results are achieved will the water be re-used.  In cases where a mikveh has gardens, the recycled water will be used for irrigation.  In other cases, the water can be used for flushing toilets.

The timing of the project coincides with a recent initiative in the Knesset that all newly constructed large buildings should incorporate conservation methods that include gray water purification systems.  Friedler says he hopes the pilot program will be part of an integrated effort between the authorities and the group running the mikveh project to find viable ways for accomplishing those goals.

Although Israel’s Health Ministry has historically prohibited gray water recycling because of unacceptably high bacteria counts in such water, they are actively involved in the mikveh project.

“This project is important, most of all to educate people about gray water,” said David Weinberg, national planning and treated-effluent engineer at the Health Ministry. “Most people don’t realize how many disease-causing bacteria there are in untreated gray water.”  He also said that such treatment would require constant monitoring by local authorities or businesses.

“These applications are designed for large-scale use, and operation maintenance is a critical issue,” said Friedler. “If you don’t have a high percentage of application and maintenance by professionals, it won’t work.”

If successful, the pilot project could someday be expanded for implementation in hotels, community centers, health clubs and other facilities.

According to Garmaise, the project has received generous support from the Richard and Rhoda Goldman Fund, but she added that additional funding is still being sought to ensure implementation of the project’s full scope.

The Technion-Israel Institute of Technology is Israel's leading science and technology university.  Home to the country's winners of the Nobel Prize in science, it commands a worldwide reputation for its pioneering work in nanotechnology, computer science, biotechnology, water-resource management, materials engineering, aerospace and medicine.  The majority of the founders and managers of Israel's high-tech companies are alumni. Based in New York City, the American Technion Society ( is the leading American organization supporting higher education in Israel, with offices around the country.


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