Reclaimed water, sometimes called recycled water, is former wastewater (sewage) that has been treated to remove solids and certain impurities, and then allowed to recharge the aquifer rather than being discharged to surface water. This recharging is often done by using the treated wastewater for irrigation. In most locations, it is only intended to be used for nonpotable uses, such as irrigation, dust control, and fire suppression, and there is controversy about possible health and environmental effects for those uses. In some locations (not in the United States), it is given more advanced treatment and is used indirectly for drinking.
Los Angeles County's sanitation districts have provided treated wastewater for landscape irrigation in parks and golf courses since 1929. The first reclaimed water facility in California was built at San Francisco's Golden Gate Park in 1932. In Southern California, Irvine Ranch Water District and Orange County Water District are becoming the leaders in reclaimed water through their Green Acres Project.
Using reclaimed water for non-potable use saves potable water for drinking, since less potable water will be used for non-potable uses.
More recently, Chang(2007) reported that Staphyloccus aureus bacteria (responsible for MRSA) become more virulent and drug resistant after chlorination. A large study in 2006 confirms that microbes, inactivated but not killed by treatment, can regrow in retention ponds and pipes, becoming a major source of the spread of multi drug resistant pathogens in the environment. During the processing of reclaimed water, fragments can be released from microbes when their cell walls are disrupted. These fragments are not alive and not affected by disinfectants like chlorine. This intact genetic material can transfer both virulence and drug resistance to living microorganisms in water or soil. Amy Pruden(2006) demonstrates that such genetic fragments pass through sewer water reclamation plants into rivers and into drinking water sources. Since the number and types of bacteria in a treatment plant are large, a positive environment exists for transfer of drug resistance. Independent scientists found that Santa Barbara's reclaimed water contained chlorine resistant bacteria that were also resistant to eleven of the twelve antibiotics tested.
There is also concern in the industry about organic chemicals, including endocrine disruptors in wastewater In 2005,US Dept of Agriculture reported:"Overall, the environmental and public health impacts of irrigation with reclaimed sewage effluent and the potential degradation of underlying groundwater are largely unknown",
In most locations, reclaimed water is not directly mixed with potable (drinking) water for several reasons:
Because of this, state regulatory agencies do not allow reclaimed water to be used for drinking, bathing, or filling swimming pools. They also warn those who use reclaimed water for irrigation to place a sign on their property warning people not to drink from the irrigation system, and to not use it directly on fruits or vegetables.
Unplanned Indirect Potable Use has existed even before the introduction of reclaimed water. Many cities already use water from rivers that contain effluent discharged from upstream sewage treatment plants. There are many large towns on the River Thames upstream of London (Oxford, Reading, Swindon, Bracknell) that discharge their treated sewage into the river, which is used to supply London with water downstream. This phenomenon is also observed in the United States, where the Mississippi River serves as both the destination of sewage treatment plant effluent and the source of potable water. Research conducted in the 1960s by the London Metropolitan Water Board demonstrated that the maximum extent of recycling water is about 11 times before the taste of water induces nausea in sensitive individuals. This is caused by the build up of inorganic ions such as Cl-, SO42-, K+ and Na+, which are not removed by conventional sewage treatment.
In the United States, reclaimed waste water is generally treated to secondary level when used for irrigation, but there are questions about the adequacy of that treatment. Some leading scientists in the main water society, AWWA, have long believed that secondary treatment is insufficient to protect people against pathogens, and recommend adding at least membrane filtration, reverse osmosis, ozonation, or other advanced treatments for irrigation water.
Seepage of nitrogen and phosphorus into ground and surface water is also becoming a serious problem, and will probably lead to at least tertiary treatment of reclaimed to remove nutrients in future. Even using secondary treatment, water quality can be improved. Testing for pathogens using Polymer Chain Reaction (PCR) instead of older culturing techniques, and changing the discredited fecal coloform "indicator organism" standard would be improvements. In a large study treatment plants showed that they could significantly reduce the numbers of parasites in effluent, just by making adjustments to the currently used process. But, even using the best of current technology,risk of spreading drug resistance in the environment through wastewater effluent, would remain. Some scientists have suggested that there need to be basic changes in treatment, such as using bacteria to degrade waste based on nitrogen(urine) and not just carbonaceous (fecal) waste, saying that this would greatly enhance effectiveness of treatment. Currently designed plants do not deal well with things in solution, ie: pharmaceuticals. "Dewatering" solids is a major problem. Some wastes could be disposed of without mixing them with water to begin with. In an interesting innovation, solids (sludge) could be removed before entering digesters and burned into a gas that could be used to run engines. Emerging disinfection technologies include ultrasound, pulse arc electrohydrolic discharge, and bank filtration. Another issue is concern about weakened mandates for pretreatment of industrial wastes before they are made part of the municipal waste stream. Some also believe that hospitals should treat their own wastes. The safety of drinking reclaimed water which has been given advanced treatment and blended with other waters, remains controversial.
In many cities using reclaimed water, it is now in such demand that consumers are only allowed to use it on assigned days. Some cities that previously offered unlimited reclaimed water at a flat rate are now beginning to charge citizens by the amount they use.
The leaders in use of reclaimed water in the U.S. are Florida and California, with Irvine Ranch Water District as one of the leading developers. They were the first district to approve the use reclaimed water for in-building piping and use in flushing toilets.
As Australia continues to battle the 7-10 year drought, nationwide, reclaimed effluent is becoming a popular option. Already three major and capital cities in Australia, have committed to adding reclaimed effluent to their dwindling dams, including Adelaide, Brisbane and indirectly Sydney. Brisbane has been seen as a leader in this trend, and other cities and towns will review the 'Western Corridor Recycled Water Project' once completed. Already Goulbourn, Canberra, Newcastle, and Regional Victoria, Australia are also considering building a reclaimed effluent process.
According to a EU-funded study "Europe and the Mediterranean countries are lagging behind" California, Japan or Australia "in the extent to which reuse is being taken up." According to the study "the concept (of reuse) is difficult for the regulators and wider public to understand and accept."
A less elaborate alternative to reclaimed water is a greywater system. Greywater is wastewater that has been used in sinks, baths, showers, or washing machines, but does not contain sewage (see blackwater). In a home system, treated or untreated greywater may be used to flush toilets or for irrigation. Some systems now exist which directly use greywater from a sink to flush a toilet or even combine the two into one piece of furniture.
Perhaps the simplest option is a rainwater harvesting system. Although there are concerns about the quality of rainwater in urban areas, due to air pollution and acid rain, many systems exist now to use untreated rainwater for nonpotable uses or treated rainwater for direct potable use. There are also concerns about rainwater harvesting systems reducing the amount of run-off entering natural bodies of water.
Austin, TX http://www.ci.austin.tx.us/wri/
water pinch analysis. The techniques helps a user to target the minimum freshwater consumption and wastewater target. It also helps in designing the network that achieves the target. This provides a benchmark to be used by users in improving their water systems.