Reclaimed water

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Reclaimed water is wastewater (sewage) that has been treated and purified for reuse, rather than discharged into a body of water. It is frequently used to irrigate golf courses and parks, fill decorative fountains, and fight fires. It can also be used to irrigate crops, as long as they will be peeled or boiled before human consumption.

Contents 1 Definition 2 Benefits 3 Suitable for drinking? 4 Distribution and demand 5 Some locations using reclaimed water 5.1 Potable use 5.2 Indirect potable use 5.3 Non-potable use 5.4 Proposed 6 See also 7 References

[edit] Definition

Treated effluent from wastewater treatment facilities is typically discharged directly into a stream, river, or other body. This recharges the water supply and promotes the natural decomposition of materials in the water that standard treatment practices would not normally be able to remove. But due to increasing population and increasing demand for reliable fresh water sources, many areas around the world are now using reclaimed water to decrease potable water demands.

In a basic sense, reclaimed water is treated effluent that—instead of being discharged into a natural body of water—is treated to a higher degree (depending on the location) and is used for a broad range of practical purposes, most commonly irrigation.

Many cities across the United States have exercised the use of reclaimed water as a result of discharge restrictions or low fresh water supplies. Arid climates, high populations, and close proximity to oceanic saltwater intrusion have been the most proactive of all the users of reclaimed water.

[edit] Benefits

The costs involved with reclaimed water typically exceed those of standard potable water in most regions of the world, where a fresh water supply is plentiful. However, in areas where supplies of fresh water are limited, treating wastewater for reuse is becoming an economically attractive option, because it conserves drinking water. This is why many cities in Southwestern United States make use of reclaimed water.

Reclaimed water is usually sold to citizens at a cheaper rate than standard drinking water. It also contains higher levels of nitrogen and phosphorus, which help fertilize plants when used for irrigation.

[edit] Suitable for drinking?

Reclaimed water is not directly mixed with potable (drinking) water for several reasons:

• Humans may face psychological barriers against drinking reclaimed water, since it was formerly sewage.
• Small amounts of pathogens and pharmaceutical chemicals are able to pass through the filtering process, potentially causing danger to humans. Modern technologies such as Reverse Osmosis are helping to overcome this problem. An experiment by the University of New South Wales showed a Reverse Osmosis system removed Ethanol Estradiol and Paracetamol from the waste water, even at 1000 times the expected ppm.^[1]
• Many utilities providing reclaimed water for nonpotable uses do not treat the water to drinking water standards.

Because of this, regulatory agencies ban people from drinking, bathing in or filling swimming pools with reclaimed water. Those who irrigate their lawn or plants with reclaimed water should place a sign on their property warning people not to drink from the irrigation system, and reclaimed water should not be sprayed directly on fruits or vegetables.

Some municipalities are now investigating either potable or indirect potable use of reclaimed water. For example, reclaimed water may be pumped into reservoirs where it will mix with (and be diluted by) rainwater. This mixture of rainwater and reclaimed water could then be treated again, and finally used as drinking water. This technique may also be referred to as groundwater recharging or reservoir augmentation.

Some cities using water from rivers are using water that contains effluent discharged from upstream sewage treatment plants. It is sometimes said that water in London has been drunk five times before it arrived at the tap, but this is an exaggeration. 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^-, SO4^2-, K⁺ and Na⁺, which are not removed by conventional sewage treatment.

[edit] Distribution and demand

Reclaimed water is 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.

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.

A less elaborate alternative to reclaimed water is a greywater system. Greywater has been used in sinks, washing machines or showers, but does not contain sewage (blackwater). In a home system, untreated grey water may be used to flush toilets or for irrigation. In a city-wide system, grey water may flow in a set of pipes separate from other sewage to a treatment plant, where it can be treated and used in similar ways as reclaimed water.^{[citation needed]}

[edit] Some locations using reclaimed water

[edit] Potable use

• Singapore (where it is branded as NEWater)

[edit] Indirect potable use

• Payson, AZ^[2]

See also: Indirect potable use.

[edit] Non-potable use

• Tucson, Arizona^[3]
• Clark County, Nevada^[4]
• Clearwater, Florida^[5]
• St. Petersburg, Florida^[6]
• San Diego, California^[7]

[edit] Proposed

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

• Goulburn, New South Wales, Australia (proposed for potable use as of July 2006).^[8]
• Brisbane, Queensland, Australia (possable Referendum in 2007 for Potable use).^[9]
• Newcastle, New South Wales, Australia (proposed for non-potable use).^[10]

[edit] See also

• Greywater
• Sewage treatment
• Water conservation
• Water filtration

[edit] References

1. ^ From the Toilet to the Tap
2. ^ Green Valley Park Lakes Groundwater Recharge Project.
3. ^ Reclaimed Water
4. ^ Water Reclamation
5. ^ Making the Connections: Reclaimed and Drinking Water Supplies
6. ^ Water Systems Maintenance Mission Statement
7. ^ Recycled Water
8. ^ Goulburn to decide on recycled water within months ABC News 30 July 2006.
9. ^ Qld Govt to hold referendum on recycled water. The World Today 20 November 2006.
10. ^ Recycling plant brings region closer to being drought proof. ABC News 19 July 2006.