Gray Water System

Gray Water

Gray water refers to the waste water from bathing (shower and sink), washing dishes, cooking, and laundry. The term “gray water” comes from the appearance of water that is not as clear as drinking water, but is cleaner and less contaminated than waste water from a toilet, or water contaminated with chemicals.  The water discharged by the flush of a toilet is called “black water,” named for its appearance that is tainted by fecal matter. Black water also refers to water containing a high percentage of toxic chemicals such as bleach. The cleaning process of black water is more complex than the purification process of the gray water.

Gray water System in The Solar Garden

We have two different gray water purification systems:

  • The first is a biological system for purification of gray water that uses different plants’ roots to filter the water. Roots act as natural filters for small particles and organic matter that would otherwise contaminate water. The particles are trapped in the roots which are splayed out in the water, so the water is cleansed as it flows through each different plant area. The water from this system is used to fill fish ponds in the garden. This system was donated by the Israeli company “Yerakrak.”
  • The second system, donated by the Israeli company “Hydro- Systems,”  is an antiseptic system  that eliminates germs and contaminants from the water. The water cycles through 3 different filtration systems, including one with UV rays that kills any germs still lurking in the water. The water from this system is used to irrigate most of our garden’s vegetation.

During a tour of The Solar Garden you can see how complex the systems are. Our instructors will explain the purification and filtration methods and we will stage a demonstration done by the visitors.

In The Solar Garden, once our water is filtered and purified it is pumped throughout our garden and used for irrigating trees and plants. Our gray water system is also used to fill our fish ponds.

The Importance of Gray Water Purification

The creation and sustenance of all plant and animal life on Earth depends on the existence and availability of fresh water. About 80% of Earth covered by water, 97% of which are oceans, which contain saltwater (not fresh water).  Less than 3% of water on Earth is fresh water. Most of this tiny percentage is trapped in glaciers, and are not available for use. The rest lies in rivers and lakes.

Human activities have caused reduction of fresh water resources available in the world. Rapid population growth has put pressure on water sources in many parts of the world. We pump too much water from beneath the earth, so water is removed for use faster than it is renewed. Lowering water levels in underground aquaphors create a higher percentage of water unsuitable for use, because the salt and other potential contaminants increase while the amount of actual water decreases. Use of progressive technologies like gray water systems increases our ability to produce fresh water and reuse water we already pumped, instead of pumping new water, and leaving the previously used water that is still salient, by the wayside.

Sometimes waste products from either industrial, household, or agricultural items with chemicals make their way into our water, which makes it unusable, thereby contributing to the problem of our declining water quality and frequent shortages. This is a big problem in our region, and the situation will only become more dire unless we change the attitude of the masses. Conserving water from our already diminished suppy is the greatest environmental challenge currently facing Israel.

There are a few Israeli companies that produce purification systems and gray water filters to allow us to reuse our gray water for watering plants in the garden or to refill toilet tanks. There are many water filtration and purification methods, but incorrect handling of gray water can cause health problems, plumbing issues or contamination, so the utmost care is imperative.

When using a gray water system, be sure to use ecological cleaning products and soaps, because they do not contain hazardous chemicals and complex material. Environmentally friendly products disintegrate quickly and do not contaminate the water they are used in conjunction with.

Israel’s Water Consumption

Israel’s domestic water consumption ranges from 100- 230 liters per capita per day, with an average of 165 liters per capita. About 47% of it can be recycled in the form of gray water for reuse, especially for irrigating gardens.

Average Distribution of Family Water Consumption in Israel (as of 2009):

35% – toilet flushing
5% – gardening
32% – bath and shower water (gray water)
14% -laundry (gray water)
6% – hand and face washing
5% – drinking water and cooking
3% – sink water (gray water)


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