Graywater Reuse in Other Countries and its Applicability to Jordan -- continued --

2.0   Graywater Reuse in Other Countries

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The reuse of graywater is being increasingly practiced in a number of countries, whose water crisis is less critical. A number of these countries have carried out assessments of graywater reuse practices and investigated the technical means of reuse as well as the health and environmental implications. The following are some jurisdictions where information on graywater reuse has been found, and where graywater reuse is currently being practiced.

In the US, no national guidelines exist, as individual states are responsible for their own regulation of water and plumbing. Several states have developed legislation to allow graywater reuse in different circumstances. California was the first state to study and permit the reuse of graywater. Graywater was being permitted in Santa Barbara as early as the 19th Century.  A pilot study into graywater reuse in the Los Angeles area was carried out in the 1980s. A Code to regulate the reuse of domestic graywater was issued in 1977 and is currently under revision. In Arizona, graywater is permitted for use in household irrigation. Numerous trials, studies and assessments have been carried out, and reported. Guidelines for graywater reuse have also been prepared. A 2000 study showed that graywater reuse was common in Arizona for irrigation of shade and ornamental trees, even before legislation and guidance were available (Residential Greywater Reuse June 2000).

Studies in Australia published in 1994 and 1997 (Jeppesen and Solley 1984; Anda and Matthew 1997) were carried out to assess the potential for graywater reuse there. The study concluded that significant water savings could be made from the responsible reuse of graywater, provided adequate safeguards were followed. No information regarding the degree for graywater reuse in Australia has been uncovered.

Cyprus has initiated a subsidy program for households that wish to install graywater reuse systems for domestic landscaping and toilet flushing. There is also documentation of graywater reuse at certain hotels and at least one sports facility. Dual plumbing systems have also been introduced to allow the reuse of graywater in toilet flushing (Kambanellas 1999).

Agencies in the UK (Environment Agency, CIRIA and BSIRIA) have published studies on graywater treatment and reuse for toilet flushing (CIRIA 2001). These studies investigated a number of operational pilot plants in various parts of the country, where graywater was captured and treated for use in toilet flushing. Filtration and disinfection were employed to raise the quality of the water to the desired standards. It is estimated that around 150 graywater ‘units’ were in operation around the country.  The studies have concluded that water savings could result but cited issues of reliability and maintenance as needing to be overcome before graywater reuse could be promoted on a more widespread basis. The reports also cite lack of financial incentives due to the cost of graywater systems, and the low cost of water.  It is clear that the level of complexity of treatment and operation of graywater systems designed to produce water for toilet flushing is considerably more complicated than for garden irrigation, and leads to increased operation and maintenance costs.

Although legal in Germany, the use of graywater recycling systems has been limited. Instead, rainwater collection for toilet flushing is the favored option, due to the higher quality water available from this source.

Graywater reuse is also practiced in Japan on a scale that ranges from the use of simple hand basin urinals in residential properties that flush the bowl using water from hand washing, to complex recycling systems in office blocks. In Tokyo, graywater recycling is mandatory for buildings with an area over 30,000 square meters or with potential reuse of 100 cubic meters/day (Hanson 1997).

Pilot studies have also been carried out by the Islamic Network for Water Resource Demand Management (INWRDAM) in Palestine and Lebanon, although graywater reuse in these countries is not thought to be widespread (see network.idrc.ca/ev.php ).

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The science behind the safe reuse of domestic graywater for irrigation is not difficult. Graywater is captured from the various household sources (sinks, hand-basins, showers, etc), and taken (possibly through a simple treatment system and maybe storage) to a distribution system. In the case of reuse for toilet flushing, often a slightly more sophisticated treatment and storage is required.  The components of any type of graywater system may therefore be summarized as follows:

• Sources of Graywater

• Collection of Graywater

• Treatment of Graywater

• Storage of Graywater

• Use of Graywater

Although there are differences in how graywater is used in various countries, there are broad similarities at each stage of the process. The following is a discussion of the main features of graywater sources, collection, treatment, storage and reuse, based on an examination of research and studies conducted in other countries. Much of the following information is taken from the publications listed in the reference section.

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Graywater is the term used for normal household liquid wastes, other than toilet wastes. In most countries, the sources of domestic graywater are the same. They include wastewater that flows from baths, bathroom sinks, bathroom showers, and wash basins. Laundry water from clothes washing machines and laundry tubs is also used in many areas. However, this often contains suspended solids and high concentrations of chemicals, and may cause problems if the graywater is to be reused for irrigation. For this reason, the reuse of laundry water sometimes is discouraged.

However, it seems that both bathroom and laundry water are generally less polluted than kitchen sink water, and so are easier to reuse. In many areas (e.g. Arizona, California, and New Mexico) water from the kitchen sink and automatic dishwasher are prohibited from entering the graywater stream since they are high in suspended solids, fats, oils, and grease, and their generally high organic content encourages the growth of bacteria. Also, the high fat and solid content cause problems for filtration and pumping. It is generally recommended that kitchen water be directed to the sewage collection system. However, some sources (www.oasisdesign.net) consider the levels of bacteria in kitchen wastewater to have been vastly overestimated, and that kitchen sink water should not be automatically ruled out for graywater reuse. This remains an issue under debate, and in Arizona, consideration is being given to a lifting of the blanket ban on kitchen water in certain circumstances. In fact, there are examples of long-term use of kitchen sink water with no adverse effects on plants.

Other potential graywater sources include swimming pool water. Collected rainfall runoff is also an important source of reusable water, but is usually of a higher quality than graywater, and is not the subject of this investigation.

2.1.2   Collection of Graywater

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Collection of the graywater is simple in concept, but is one of the more practically difficult aspects of reusing graywater. In the simplest case, graywater can be collected simply by placing a bucket below an open sink drain, and manually transported to the point of use. However, a piped system requires less user intervention and is more ideal from a public health perspective since it eliminates contact between graywater and user. In this case, a plumbing network simply takes the graywater, keeping it separate from the non-graywater, and directs the graywater to a point where it can be stored, treated, or reused.

The details of such systems vary from country to country, but they are generally gravity collection systems that use ordinary plumbing components. In new houses, the installation of such a ‘dual-plumbing’ system to separate useable graywater from non-useable ‘blackwater’ is simple and requires little extra expense. However, retrofitting such a dual system into an existing building may require more difficult installation work, depending on the design of the house and the plumbing system.