Reclaimed water is used in Santa Monica, California to irrigate plants in public parks and municiple landscapes.

Reclaimed water, sometimes called recycled water, is former wastewater (sewage) that has been treated to remove solids and certain impurities, and then used in Sustainable landscaping irrigation or to recharge groundwater aquifers. These are done,for sustainability and water conservation, rather than discharge the treated wastewater to surface waters such as rivers and oceans.

The recycling and recharging is often done by using the treated wastewater for designated municipal sustainable gardening irrigation applications. In most locations, it is intended to be only used for nonpotable uses, such as irrigation, dust control, and fire suppression. There is debate about possible health and environmental effects with its uses. However, 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. The Irvine Ranch Water District and Orange County Water District in Southern California are becoming the leaders in reclaimed water through their 'Green Acres Project.' Also in Orange County, and in other locations such as Singapore, water is given more advanced treatments and is used indirectly for drinking.[1][2]


Storm and sanitary sewers were necessarily developed along with the growth of cities. By the 1840s the luxury of indoor plumbing, which mixes human waste with water and flushes it away, eliminated the need for cesspools. Odor was considered the big problem in waste disposal and to address it, sewage could be drained to a lagoon, or "settled" and the solids removed, to be disposed of separately. This process is now called "primary treatment" and the settled solids are called "sludge."

At the end of the 19th century, since primary treatment still left odor problems, it was discovered that bad odors could be prevented by introducing oxygen into the decomposing sewage. This was the beginning of the biological aerobic and anaerobic treatments which are fundamental to waste water processes.

By the 1920s, it became necessary to further control the pollution caused by the large quantities of human and industrial liquid wastes which were being piped into rivers and oceans, and modern treatment plants were being built in the US and other industrialized nations by the 1930s.[3]

Designed to make water safe for fishing and recreation, the Clean Water Act of 1972 mandated elimination of the discharge of untreated waste from municipal and industrial sources, and the US federal government provided billions of dollars in grants for building sewage treatment plants around the country. Modern treatment plants, usually using sand filtration and chlorination in addition to primary and secondary treatment, were required to meet certain standards.[4]

Current treatment improves the quality of separated wastewater solids or sludge. The separated water is given further treatment considered adequate for non potable use by local agencies, and discharged into bodies of water, or reused as reclaimed water. In places like Florida, where it is necessary to avoid nutrient overload of sensitive receiving water, reuse of treated or reclaimed water can be more economically feasible than meeting the higher standards for surface water disposal mandated by the Clean Water Act [5]

Maximum Water RecoveryEdit

To determine Maximum Water Recovery there are various techniques that have been developed by researchers; for maximum water reuse/reclamation/recovery strategies such as 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.


The cost of reclaimed water exceeds that of potable water in many regions of the world, where a fresh water supply is plentiful. However, reclaimed water is usually sold to citizens at a cheaper rate to encourage its use. As fresh water supplies become limited from distribution costs, increased population demands, or climate change reducing sources, the cost ratios will evolve also.

Using reclaimed water for non-potable uses saves potable water for drinking, since less potable water will be used for non-potable uses.

It sometimes contains higher levels of nutrients such as nitrogen, phosphorus and oxygen which may somewhat help fertilize garden and agricultural plants when used for irrigation.

The usage of water reclamation decreases the pollution sent to sensitive environments. It can also enhance wetlands, which benefits the wildlife depending on that eco-system. For instance, The San Jose/Santa Clara Water Pollution Control Plant instituted a water recycling program to protect the San Francisco Bay area's natural salt water marshes.[6]


Recent studies support long standing concerns about possible public health effects of reclaimed water. It has been known for some time that treated waste water effluent, or reclaimed water, contains pathogens that could be transferred to people through contact, including aerosols from sprinklers. Particularly worrisome are high levels of parasites such as giardia and cryptosporidium which are not killed by chlorination. Drip and subsurface irrigation technology applications circumvent this.

[7] In 1997, the United States Environmental Protection Agency warned, "(Viable) bacteria from reclaimed water in sprinklers can travel more than 1000 feet in the air." [8] As far back as 1984, researchers concluded that disinfection by chlorination, an important part of wastewater treatment, initially lowers the total number of sewage related bacteria, but may substantially increase the proportions of antibiotic resistant, potentially pathogenic organisms.[9]

More recently, Chang (2007) reported that Staphylococcus aureus bacteria (responsible for MRSA) become more virulent and drug resistant after chlorination.[10] 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.[11] 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.[12] Since the number and types of bacteria in a treatment plant are large, and are exposed to antibiotic pharmaceuticals in wastewater, 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.[13]

There is also concern in the industry about organic chemicals, including endocrine disruptors in wastewater.[14] In 2005, the United States Department 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." [15]

Distribution and demandEdit

Reclaimed water is often distributed with a dual piping network that keeps reclaimed water pipes completely separate from potable water pipes. In the United States, reclaimed water is always distributed in lavender (light purple) pipes to distinguish it from potable water.[16][17]

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.[citation needed]

Testing standardsEdit

Reclaimed water is not regulated by the EPA but by the states, using standards formulated decades ago. Newer information shows serious public health concerns about pathogens in the water.[18] Many pathogens cannot be detected by currently used tests.[19]

Recent literature also questions the validity of testing for "indicator organisms" instead of pathogens.[20] Nor do present standards consider interactions of heavy metals and pharmaceuticals which may foster the development of drug resistant pathogens in waters derived from sewage.[21]

Potable usesEdit

In most locations, reclaimed water is not directly mixed with potable (drinking) water for several reasons:

  • Utilities providing reclaimed water for nonpotable uses do not treat the water to drinking water standards.
  • Varying amounts of pathogens, pharmaceutical chemicals (e.g., hormones from female hormonal contraception) and other trace chemicals are able to pass through the treatment and filtering process, potentially causing danger to humans. Modern technologies such as reverse osmosis may help to somewhat overcome this problem. An experiment by the University of New South Wales reportedly showed a reverse osmosis system removed ethinylestradiol and paracetamol from the wastewater, even at 1000 times the expected concentration.[22]
  • Drinking water standards were developed for natural ground water, and are not appropriate for identifying contaminants in reclaimed water. In addition to pathogens, and organic and endocrine disrupting chemicals, a large number of compounds may be present in reclaimed water. They cannot all be tested for, and there is a paucity of toxicity information on many of the compounds.[23]

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.

Aboard the International Space Station, astronauts have been able to drink recycled urine due to the introduction of the ECLSS system. The system cost $250 million and has been working since May 2009. The system recycles wastewater and urine back into potable water used for drinking, food preparation, and oxygen generation. This cuts back on the need for resupplying the space station so often.[24]

Indirect Potable useEdit

Some municipalities are now investigating Indirect Potable Use (IPU) of reclaimed water. For example, reclaimed water may be pumped into (subsurface recharge) or percolated down to (surface recharge) groundwater aquifers, pumped out, treated again, and finally used as drinking water. This technique may also be referred to as groundwater recharging.

Unplanned Indirect Potable useEdit

Unplanned Indirect Potable Use[25] 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.

Space travelEdit

Wastewater reclamation can be especially important in relation to human spaceflight.

Treatment improvementsEdit

As world populations require both more clean water and better ways to dispose of wastewater, the demand for water reclamation will increase. Future success in water reuse will depend on whether this can be done without adverse effects on human health and the environment.

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.[28]

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.[29] Even using secondary treatment, water quality can be improved. Testing for pathogens using Polymerase Chain Reaction (PCR) instead of older culturing techniques, and changing the discredited fecal coloform "indicator organism" standard would be improvements.

In a large study [30] 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 improve effectiveness of treatment.[31] Currently designed plants do not deal well with contaminants in solution (e.g. 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.[32]

Emerging disinfection technologies include ultrasound, pulse arc electrohydrolic discharge, and bank filtration.[33] Another issue is concern about weakened mandates for pretreatment of industrial wastes before they are made part of the municipal waste stream.[5] 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.

Other alternativesEdit

In urban areas where climate change has threatened long-term water security and reduced rainfall over catchment areas, using reclaimed water for indirect potable use may be superior to other water supply augmentation methods. One other commonly used option is seawater desalination. Recycling wastewater and desalinating seawater may have many of the same disadvantages, including high costs of water treatment, infrastructure construction, transportation, and waste disposal problems. Although the best option varies from region to region, desalination is often superior economically, as reclaimed water usually requires a dual piping network, often with additional storage tanks, when used for nonpotable use.

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.[34] Some systems now exist which directly use greywater from a sink to flush a toilet[35] or even combine the two into one piece of furniture[36].

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.

Worldwide applications and acceptanceEdit

The leaders in use of reclaimed water in the U.S. are Florida and California,[37] with Irvine Ranch Water District as one of the leading developers. They were the first district to approve the use of 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. Two major capital cities in Australia, Adelaide and Brisbane, have already committed to adding reclaimed effluent to their dwindling dams. 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. Goulbourn, Canberra, Newcastle, and Regional Victoria, Australia are already considering building a reclaimed effluent process.

According to a EU-funded study, "Europe and the Mediterranean countries are lagging behind" California, Japan, and 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."[38]

Reclaimed water applicationsEdit

Indirect potable useEdit

Non-potable useEdit


In some places, reclaimed water has been proposed for either potable or non-potable use:


See alsoEdit

External linksEdit

  • Waterwise A nonprofit non-governmental Organization dedicated to promoting the wise use of water.
  • WateReuse A nonprofit Organization whose mission is to advance the beneficial and efficient use of water resources using reclamation, recycling, reuse, and desalination.
  • Watchers Protecting the Environment A nonprofit Organization dedicated to finding the truth about reclaimed sewage water and sludge.
  • Help for Sewage Victims A nonprofit Organization dedicated to factual research for the protection of sewage victims.


  1. NEWater FAQ, accessed 8 January 2007.
  2. Orange County Water District's Groundwater Replenishment System, accessed 6 March 2009
  3. P.F.Cooper,2001, Decentralized Sanitation and Reuse, Chapt.2, IWA Publishing, London,UK.
  4. 33 Usc 1251 seq., 1972, Federal Water Pollution Control Act, Enacted by Congress.
  5. 5.0 5.1 Sierra Club Fact Sheet
  7. Gennaccaro, McLaughlin, Betancourt, Huffman and Rose, Infectious Cryptosporidium parvum Oocysts in Final Reclaimed Effluent, Dept Marine Science, U of South Florida, St Petersburg, Florida.
  8. EPA Guidelines for Water Reuse, (1996)
  9. GE Murray, RS Tobin, B Junkins, DJ Kushner,(1984) Effect of Chlorination on antibiotic resistance profiles of sewage-related bacteria, Appl Environ Microbiol. July 1998:48(1): 73-74
  10. Matthew Wook Chang, Freshteh Toghrol, William Bentley, Toxicogenomic Response to Chlorination Includes Induction of Major Virulence Genes in Staphylococcus aureus,Environ. Sci. Technol., 41(21)7570-7575.
  11. Timothy Lapara, Sara Firl,(2006) The Importance of Municipal Sewage Treatment in the Spread of Antibiotic resistance,100th General Meeting of the American Society for Microbiology, May 21–25, 2006. Orlando Fl.
  12. Amy Pruden, 2006, Antibiotic Resistance genes as emerging contaminants, Studies in Northern Colorado, Environmental Science Technology 40, 7445-7450
  13. Edo Mcgowan, (2008) The Watchers.US/edo_politics-reclaimed-water.html-74k
  14. Maria Burke (2004),UK to tackle Endocrine Disruptors in Wastewater, Technology News, September 1,2004.
  15. US Dept of Agriculture, 2005 Report
  16. Rules and Regulations for Reclaimed Water. City of San Diego. 31 January 2007.
  17. Purple Rain Education Program. Pasco County, Florida. 31 January 2007.
  18. Timothy LaPara, Sara Firl, 2006, The Importance of Municipal Sewage Treatment in the spread of Antibiotic resistance, 106th General Meeting of the American Society for Microbiology.
  19. James D. Oliver, 2005, The Viable but Nonculturable State in Bacteria, J. of Microbiology p.93-100.
  20. Valerie J. Harwood, Audry D. Levine, Troy M. Scott, Joan G. Rose, 2005,Validity of the Indicator Organism Paradign for Pathogen Reduction in Reclaimed Water and Public Health Protection, Applied and Environmental Microbiology, Vol.71.
  21. Tsai, Kan-Jen (2008). "Bacterial Heavy Metal Resistance". Osaka Biology. Retrieved 2008-05-11. 
  22. From the Toilet to the Tap, Australian Broadcasting Corporation 9 November 2006
  23. Committee on the Viablility of Augmenting Drinking Water Supplies with Reclaimed water, 1998, Issues in Potable Reuse, National Research Council
  24. (2009, May 20). Astronauts Drink Recycled Urine, and Celebrate. Retrieved November 29, 2009 from
  25. Public Utilities Board, Overseas Experiences, accessed 24 April 2007.
  26. University of Colorado
  27. Scientific American Frontiers
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  32. Ken Stedman, 2007, Micromedia Filtration Inc helps Gold Village Come Clean, Press Release
  33. Jess C. Brown and Andrew Salveson, 2007, Emerging Disinfection Technologies Florida Resources Journal, July 6.
  34. Grey Water 31 January 2007.
  35. WaterSaver Technologies Aqus Uses Sink Greywater for Toilet. October 7, 2006. Retrieved May 22, 2007.
  36. Toilet Lid Sink. Gaiam. Retrieved May 22, 2007.
  37. UF Professor: Drought Highlights Value Of Reused Water. University of Florida News. May 24, 2000.
  38. 38.0 38.1 "Reuse of water in the EU and the Mediterranean", by Bill McCann, Water 21, Journal of the International Water Association, April 2008, p. 42-44, quoting the Aquarec project
  39. Green Valley Park Lakes Groundwater Recharge Project.
  40. [ Sydney Water Recycling Projects]
  41. Melbourne Water Recycling Projects
  42. Reclaimed Water
  43. Water Reclamation
  44. Making the Connections: Reclaimed and Drinking Water Supplies
  45. Water Systems Maintenance Mission Statement
  46. Recycled Water
  47. Delta Diablo Sanitation District, Eastern Contra Costa County
  48. Austin Water Utility
  49. Application form for access to Recycled Water (Caboolture)
  50. Beattie scraps water poll amid 'Armageddon situation'. ABC News Online 28 January 2007.
  51. Beattie defends recycled water against "scare mongers". ABC News Online 26 January 2007.
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fr:Réutilisation ou recyclage des eaux usées zh:中水

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