Greywater Recycling Overview
The water crisis in Israel is an undisputable fact. With the decline of the quantity and quality of currently available water sources, and with the growing of the population and general consumption of water, the need for effective utilization of water sources is increasing. Water conservation is a major public concern, as it is an attempt to minimize the various financial and environmental costs that result from the efforts employed to overcome the shortage of water, such as desalination and prevention of ongoing damage to aquifer.

What is Greywater?
Recycling greywater is an effective way of conserving water. In industrialized countries, approximately 150 liters of water are consumed per person per day. About 60-70% of this water turns into recyclable greywater. Greywater is a percentage of the waste water derived from domestic use, excluding toilet water, and can be divided into the categories of light and dark greywater. Light greywater includes shower water and water from sinks that are exclusively used for washing hands (such as bathroom sinks), and contains a low concentration of pollutants. Dark greywater includes water from washing machines and kitchen sinks, and contains a higher concentration of pollutants.
Greywater is a part of the sewage that contains organic substances, remainders of chemicals from cleaning fluids, and microbial and pathogenic contamination. The concentration of pollutants in greywater makes up between a third to half of the contamination in urban sewage, and as a result it can cause damage both to the environment (in the form of contamination of water sources, damaging the quality of the soil and harming plant life) and to the health of the public that comes into contact with the water

Domestic Water Consumption
Approximately 37% of the total water consumption in the country and 45% of the freshwater consumption is used for domestic and public sector purposes. Of the water consumed in homes, approximately 65% becomes greywater (see diagram 1). This segmentation of the  water use is typical of water consumption patterns in developed countries. The consumption of bathing water is similar to that used for toilet flushing - 35% for each function. Thus, use of greywater to flush toilets  can result in the conservation of approximately 35% of potatble water with an additional savings of 5% od drinking water can be attained by using greywater to irrigate lawns.

Diagram 1: Water Use Segmentation

How Does Greywater Recycling Work in a Facility?

n the current domestic systems, all the water used in the home is potable water; this water is collected in one pipe and removed as sewage. In a greywater recycling system, two pipes would be used: one pipe would remove blackwater from toilets and dark greywater from kitchen sinks directly into the sewage system; the other pipe would remove light greywater, such as bathing, laundry and bathroom sink water, and transfer it to a tank where it would be recycled. apparatus. The recycled greywater would then be returned to the house for reuse to flush toilets (instead of the valuable potable water that is currently being used for this purpose) and for watering lawns.

                
                Diagram 2: Greywater Piping Infratsructure

Considerations When Recycling Greywater
When planning for Greuwater recycling, the following issues must be considered: (for full elaboration, see attached essay)

1)      Conservation of natural resources and sustainable development

2)      Possible ways to utilize recycled water.

3)      Required levels of water quality

4)      Management of public health hazards.

5)      The effect of greywater recycling on the agricultural sector.

6)      The Economics of recycling greywater.

Greywater Recycling: Planning for the Long Term
Of the aforementioned items, the effect of greywater recycling on the agricultural sector in Israel is a particularly potent subject. Israel is the leading country in the world in the field of waste water recycling: in 2008[1], 36% of the water used for agricultural irrigation was recycled water, which constituted over 75%[2] of the total amount of water recycled in the country. Greywater makes up a percentage of sewage water; therefore, the recycling of it would essentially diminish the total amount of recycled sewage water available for irrigation. While at first glance this seems to create a situation in which greywater reuse in cities will be detrimental to agriculture, this assumption is simplistic and incorrect in practice.
Recycling greywater does not raise the urban water consumption; therefore, the reduction in the amount of sewage water is compensated for by the fact that more freshwater will be available for other uses, including for agricultural irrigation if so desired. Moreover, with the anticipated rise of population and increased levels of lifestyle in Israel, the urban water consumption is expected to rise as well. It is predicted that by the time that greywater recycling technologies are instituted on a nation-wide basis,  there will still be a surplus of treated waste water for use in agriculture . In addition, when  greywater is recycled for  toilet flushing, it  eventually will reach the central water treatment facilities which designate the treated waters for agriculture. It is important to note that local recycling would save the energy and  infrastructure needed to transport the water from great distance.

Regulation Locally and Globally
In 29 of the United States, Australia, Japan, Germany, Cyprus, Saudi Arabia, Oman and Jordan, greywater recycling is regulated by law.[3] The Australian CSIRO (Commonwealth Scientific and Industrial Research Organization) is one of the main groups involved in promoting the standardization of greywater recycling.

IAccording to world-wide standards, the official body responsible for the use of greywater is the one appointed for environmental protection. The use of greywater is usually reliant on approval from the authorities, with financial allowances for private consumers of up to 950-1500 liter per day. The legislation focuses on defining greywater within the law, the method of organization (the body in charge, type of consumers, etc.), definition of system and installation technicalities, quality of the recycled water, prevention of health hazards, methods of protecting aquifer and the public health, and guidance and conditions regarding the use of greywater.

At present, Israel does not have  regulation in place regarding greywater recycling. Over the years, the Israeli government has been unwilling to authorize greywater recycling within urban environments, the facilities of which would be installed and maintained in a decentralized fashion. This issue still poses a problem for the Ministry of Health, the authority responsible for authorization of water treatment facilities and the public health. Today, the authorities are willing to examine the possibility of recycling greywater in urban areas, and in 2008 the Ministry of Health published guidelines, in accordance with the water quality levels recommended by the Halperin Committee of 2003, regarding greywater recycling that would be permitted for watering public gardens and flushing toilets

Barriers to Recycling Greywater in Israel
In spite of the government's new willingness to examine the possibility of decentralized water recycling, there remain a number of barriers that must be addressed:

1)     The difficulty iof receiving authorization from the Ministry of Health for greywater recycling projects for a number of reasons, such as the fear of endangering the public health by using greywater in the urban sector, as is strongly expressed by the Ministry of Health, a fundamental objection to the decentralization of water treatment facilities, and a preference for transport of sewage to centralized facilities.

2)      A lack of clear regulations regarding greywater and reliance on the personal views of district engineers, with no uniformity of opinion on the part of the Ministry of Health.

3)     The conservative nature of construction entrepreneurs and contractors, and the abstention from promoting environmental causes due to regulation, financial uncertainty, as well as the obscurity regarding the image and marketing value of greywater recycling.

4)     Claims that the greywater recycling on a national level would be unprofitable due to the fact that it reduces sewage water, the recycling of which is used for agricultural irrigation; these claims may cause the agricultural lobby to raise objections as well.

5)     An engineering fear that greywater recycling will cause a lowering of the fluid ratio sewage pipes, causing the ratio of solids to rise and resulting in obstructions and transport problems. However, should this fear be realized, it would only come to pass after a major implementation of greywater recycling systems into new construction. By the time this would happen, studies on the subject that are currently in progress will have likely produced information that would facilitate   the design and adaptation of  piping systems in new neighborhoods  to prevent the problem for occuring.

The field of greywater is beginning to develop in Israel, and requires institutional involvement in order to maximize its conservation potential while managing  threats toenvironmental and public health.