Water recycling, also referred to as reclamation or reuse, is one of the ways different cities across the world are attempting to address their water issues.
In this guide, we list and explain the different pros and cons to water recycling.
Summary – Pros & Cons Of Water Recycling, Reuse & Reclamation
Water recycling (at water treatment and recycling plants) is one of the more modern water technologies.
It involves the treatment, filtration and disinfection of waste water (or any water that has been affected by human use) and storm water for different end potable and non potable uses.
Some of the major benefits of water recycling are that it diversifies a region’s water supplies, provides a climate independent water source, is beneficial for hot and dry climates, and is already widely used around the world. It can also help address water scarcity and stress, growing populations, growing demand for energy and food, water pollution from waste water, and make use of different types of water waste resources.
Some of the major disadvantages are the cost of recycled water relative to some others sources of water, and the current level of acceptance and trust the public has in recycled water.
Recycled water likely has a key part to play in the future of many regions around the world because of factors such as a changing climate, global water issues such as water stress and water scarcity becoming worse in some regions, and the potential to still capture and treat the 80% of waste water currently dumped or discharged untreated globally into the environment.
Apart from waste water, grey water, and storm water recycling, desalination, and additional rainwater harvesting are some of the other ways fresh water supplies may be sustainably managed, apart from withdrawing and consuming from surface water and ground water sources.
What Is Water Recycling?
There’s a number of definitions, but a broad one might be:
- Water that is collected or harvested, treated [to a level adequate to bring it to a quality matching it’s end use], and reused at least once before passing into the environment or or the natural water cycle
The type of water can be water affected by humans (such as waste water, or greywater), or storm water runoff.
Fluencecorp.com notes that the definition of water reuse might differ from nation to nation, including variables such as the incidence of reuse.
Types Of Water Recycling
There’s two main types of water recycling:
- Water recycling for potable water (drinking water)
- Water recycling for non potable water (non drinking water). [Recycled non drinking water taps are sometimes marked with a certain color, or have a warning label like ‘Warning: Not For Drinking’. Recycled non drinking water pipes are also sometimes marked with a certain color. Some locations in Australia for example have dedicated purple marked non drinking water pipes and taps]
De facto water reuse is also a type of water reuse (nas-sites.org)
Different Types Of Water Recycling Plants
They go by many names. A few examples include:
- Waste water treatment plant
- Advanced recycled water treatment plant
- Drinking water treatment plant
Types Of Water That Are Recycled
Different types of water can be recycled, and be re-used for different uses.
Some of the different types of water that are recycled, and what they are reused for are:
- Waste Water
As defined by sydneywater.com.au: “[Waste water is the] used water that goes down toilets, sinks and drains and into the sewerage system. Also known as sewage. About 99% of it is water”
It might also be classified as the water that outflows from a ‘sewer network, sewage treatment plant or industrial water’ (awa.asn.au)
Waste water is really any water that has been affected by human use – so, grey water is technically included in waste water (although, it’s a specific type of waste water)
Storm water is rain water that runs off of hard surfaces (roads, buildings, pavements, open land, etc.), into stormwater drains, and into local water ways.
After collection from stormwater drainage systems, it is treated and might be reused for uses such as watering lawns and gardens, and flushing toilets.
Grey water is a type of waste water. It comes from washing machines, dishwashers, showers, baths and basins at the household, building or precinct level
But, it doesn’t include waste water from toilets or kitchens, or the ‘… dishwasher as this is generally too high in grease and oil to be reused successfully without significant treatment’ (awa.asn.au)
After capture, it might be used for watering lawns and gardens.
Treatment Process For Recycled Water – How It’s Made
Depending on the end use, recycled water might go through primary, secondary, tertiary and even sometimes advanced treatments, followed by a disinfectant stage.
Read more about the recycled water treatment process here
The process though depends on the individual city, their water recycling capabilities, and the regulations in place for quality, standards and guidelines of recycled water.
Recycled water is safe when it is treated AND used according to the regulations/guidelines in place. The treatment technology usually has to meet certain outcome/performance benchmarks (for safety, and other measurements).
*[There’s also a specialized type of water re-use – called ‘indirect water reuse’ or ‘managed aquifer recharge’ where natural processes refine the water before reuse] (awa.asn.au) [Examples include recharging ground water aquifers and augmenting surface water reservoirs with recycled water] (epa.gov)
*[There can also be planned, and unplanned water recycling] (epa.gov)
Pros Of Water Recycling, Reuse & Reclamation
- Is A Way To Sustainably Manage & Use Water – re-using water is a way to not have to withdraw or consume as much new water from existing supplies. This means we preserve more of the existing water supply, but also, have more existing fresh water for drinking water and other critical or primary uses. This also helps address global water issues like water scarcity and water stress.
- Can Indirectly Help Address Other Global Issues – by conserving existing water supplies, water recycling also helps address growing populations, growing demand for energy and food (both of which require water to produce), and various types of environmental issues. It can also help replenish ground water aquifers that are depleting.
- Is Climate Independent – water recycling is a source of water that doesn’t rely on the natural climate like surface water and ground water sources do.
- Allows Diversification Of Water Sources & Water Risk Within A Region – water recycling can be one several sources of water (such as surface water, ground water, desalination) that provide fresh water to a region. This diversifies water sources and water risk as a result (because regions aren’t reliant on just one type of water source).
- Good For Dry & Hot Climates – dry climates experience lack of rainfall, and hot climates have issues such as evaporation – both of these things can impact the renewal of natural sources of water like surface water and ground water. Water recycling doesn’t have the same issues to the same extent.
- Gives Regions More Control Over Their Water – water recycling is usually done locally, so there is more control over this water, as opposed to water that might be sourced externally.
- Already Used Widely Throughout The World – for example, there are currently 14 water recycling plants in Sydney, Australia alone (sydneywater.com.au)
- Different Types Of Water Can Be Recycled – such as waste water, storm water, and grey water. These water types are considered waste products – so, water recycling helps make use of waste products and contributes to a circular economy.
- Recycling Specific Types Of Waste Water Can Have Their Own Set Of Individual Benefits – for example, reclaimed water used for agricultural irrigation may already contain certain nitrogen and phosphorus levels, and may have in built fertilizing properties … and, in agriculture “irrigation with wastewater may contribute to improve production yields, reduce the ecological footprint and promote socioeconomic benefits” (wikipedia.org)
- Recycled Water Can Be Used For Different End Uses – drinking water (potable water) is one end use. But, there’s also a long list of non drinking water uses such as irrigation of public and private land, agricultural and forestry irrigation, flushing toilets, other household water uses, fighting fires, industrial uses such as washing and cooling in power stations and factories, ground water recharge, environmental flows and wetlands, and more. [Water is even recycled and reused in space] (wikipedia.org)
- Recycled Water Can Go To Different End Recipients – such as homes, but also businesses and farms
- Water Quality Has To Meet Regulations/Laws (In Some Countries) – for example, in Australia, recycled water quality has to meet the ‘Australian Guidelines For Water Recycling’ (sydneywater.com.au). In the US “[the] EPA regulates many aspects of wastewater treatment and drinking water quality, and the majority of states in the US have established criteria or guidelines for the beneficial use of recycled water … [and the EPA has also developed a technical document] (epa.gov). Internationally, WHO, FAO and UNEP have developed guidelines for the safe use of waste water (wikipedia.org). More regulations and guidelines for different regions in the world can be found at wikipedia.org
- Can Recycle Water At High Volumes – for example the St Mary’s Advanced Water Recycling Plant is Sydney, Australia’s largest water recycling project, and produces up to 18 billion litres of very high quality water a year (sydneywater.com.au)
- Is Reliable & Consistent – recycling plants can produce X amount of water per day or per year as long as the financing and energy is there. This is in comparison to natural water sources that may vary with their reliability to provide water because of variable annual rainfall rates, and so on.
- Recycled Water Can Be Supplied Back Into The Water System Directly, Or Indirectly – through direct injection back into water pipes or water sources, or, through a scheme such as managed aquifer recharge where natural processes filter and process water before re-use. Although direct potable reuse may have more benefits (awa.asn.au)
- Potential For Waste Water Recycling Is Potentially Very High – globally, about 80% of waste water gets discharged back into the environment without being treated.
- Water Experts Largely Support Water Recycling – [in a 2014 Report] water sector professionals were largely supportive of water recycling [for both potable and non potable water uses] (awa.asn.au). One example of a city where experts think water recycling would be a beneficial long term water option is Perth, Australia.
- Human Health Problems Relating To Recycled Water Treated To Standards Are Basically Non Existent In Some Countries – accordingly to epa.gov: “No documented cases of human health problems due to contact with recycled water that has been treated to standards, criteria, and regulations have been reported [in the US]”
- People Already Drinking A Form Of Recycled Water Without Knowing It – According to abc.net.au: “[The] Thames in London, [and] every town and city on the Thames including London puts its treated wastewater into that river and they pull water out of it to drink … [people in Adelaide, South Australia are also drinking a form of recycled water too]
- Water Can Be Recycled At A Central Treatment Plant, Or On-Site – most water is collected and sent to a main water recycling plant. But, water can also be recycled on-site, like for example at an industrial facility that uses cooling processes
- Decentralized Water Recycling Sites Can Save Water, Energy & Money – According to epa.gov: “The use of gray water at decentralized sites (see definition) for landscape irrigation and toilet flushing reduces the amount of potable water distributed to these sites, the amount of fertilizer needed, and the amount of wastewater generated, transported, and treated at wastewater treatment facilities. In other words, water reuse saves water, energy, and money.” Also according to epa.gov: “Although it requires additional energy to treat wastewater for recycling, the amount of energy required to treat and/or transport other sources of water is generally much greater.”
- Has Several Environmental Benefits – such as decreasing diversion of water from ecosystems, decreasing waste water discharge and water pollution, and bettering the health of wetlands and habitats that need the water (epa.gov)
- Might Use Less Energy Than Desalination, & Be Cheaper – “Recycling waste and gray water requires far less energy than treating salt water using a desalination system.” (epa.gov). According to mercurynews.com via seametrics.com “Recycled water costs about $1,100 an acre-foot to produce, about half the cost of desalinating ocean water” (nas-sites.org). Also nas-sites: “Generally, water reuse is more expensive than drawing water from a natural freshwater source, but less expensive than seawater desalination” [and non potable waste water treatment can be most expensive if it requires separate and dedicated water pipes]
- Can Be Cost Effective Over The Long Term – over longer time periods, the cost of recycling water can average out and be more cost effective. Additionally, the benefits to the economy, environment, water supplies, and so on, should be considered as intangible things that offset some of the cost (some of these things may be priceless). Ultimately though – “The costs of water reuse vary greatly from place to place depending on location, water quality requirements, treatment methods, distribution system needs, energy costs, interest rates, subsidies, and many other factors.” (nas-sites.org). It is the cheapest to operate waste water plants and water recycling plants close to where water is traditionally supplied from (abc.net.au)
- Some Sources Indicate Water Recycling Costs No More Than Importing Water – according to kbps.org: “the future cost of recycled and imported water would be about the same, around $1,000 per acre foot”
- Some Inland Communities Benefit From Water Recycling – because technology like desalination isn’t suitable for that particular inland location due to cost, and logistics (abc.net.au)
Cons Of Water Recycling, Reuse & Reclamation
- Can Be Initially Expensive – According to epa.gov “the treatment of wastewater for reuse and the installation of distribution systems at centralized facilities can be initially expensive compared to such water supply alternatives as imported water, ground water, or the use of gray water onsite from homes”. For example, in San Diego, “A permanent water recycling plant would cost an estimated $369 million” (kpbs.org). According to abc.net.au: [In 2006/07, a $2.5 billion water scheme was commissioned,] but, water would not be used until dam levels fell to 40 per cent
- Cost To Produce Recycled Water Can Be Expensive Relative To Some Other Water Sources – in regions where fresh water is plentiful or abundant, water recycling can be more expensive than other water sources like surface water and ground water extraction and use. Costs can include construction costs, dedicated infrastructure costs, quality monitoring and identification of contaminants cost, and so on.
- Sometimes Has To Be Subsidized & Sold Below Actual Supply Cost – to encourage it’s use in some parts of the world.
- Can Need It’s Own Dedicated Infrastructure & Pipe System – in places like the US and Australia, purple or lavender marked recycled water pipes, taps and other infrastructure (like storage tanks) are dedicated to recycled water. This infrastructure costs money, and takes up space.
- Can Carry Commercial Risk & Has Economic Viability Concerns – particularly demand risk in some regions (awa.asn.au). There are questions over whether some plants can be feasible from an economic perspective, at least in the short term.
- Not All Recycled Water Can Be Used For Drinking Water, & Other Specific Uses – Sydney Water notes their recycled water can’t be used for drinking, cooking, bathing, filling pools, and a number of other uses (sydneywater.com.au)
- Public Can Be Skeptical Of Using Or Consuming Recycled Water – the public’s attitudes towards and social acceptance of recycled water can be poor, especially for some types of recycled waste water.
- Can Have Institutional Barriers To Implementation – such as water management authorities not having water recycling a priority compared to other water supply options, or regulatory barriers. In Australia for example “[there needs to be a] removal of policy barriers to potable reuse” (abc.net.au)
- Some Regions Have Inadequate Or No Regulations On Specific Types Of Water Recycling – According to epa.gov “Most states [in the US] have regulations governing water quality for water recycling of reclaimed water from centralized treatment facilities, but only about 30 of the 50 states have regulations pertaining to water recycling of gray water”
- Developing Countries May Reuse Water In An Unsafe Manner – developing countries can use untreated waste water for irrigation, which can become a public health and safety hazard. This water can also further contaminate soil and decrease soil health.
- Can Have Difficulties During Operation & Treatment Stage – From wikipedia.org: “Difficulties in contaminant identification may include the separation of inorganic and organic pollutants, microorganisms, Colloids, and others”
- Use Of Reclaimed Waste Water For Irrigation Can Have Risks – including contamination of the food chain, soil salinization and accumulation of chemicals + other risks (wikipedia.org)
- Distance Of Centralized Water Treatment Plants To Farms Can Be Too Far – the distance from farms to centralized treatment plants can be too great … but, on site treatment can solve this eventually (fluencecorp.com)
- Future Of Water Reuse Is Dependent On Many Factors – “such as economic considerations, potential uses for reclaimed water, the stringency of wastewater discharge requirements and public policies for conservation and protection” (fluencecorp.com)
Examples Of Water Recycling In The World
- In total volume, China, Mexico and the United States are the countries with the largest quantity of wastewater reuse, but in the first two cases non-treated wastewater is involved, and for China the value reported is certainly underestimated. […] If the reuse per inhabitant is considered, Qatar, Israel and Kuwait are the countries highest ranked, while when reuse is considered as the percentage of the total water used, Kuwait, Israel and Singapore become the most important.
- [Water reuse in Arab nations since 2011 has increased dramatically, whilst Europe is lagging in adoption of treated wastewater reuse]
– Blanca Elena Jiménez Cisneros, via fluencecorp.com
- [Sydney, Australia has 14 water recycling plants alone, and there are many more across Australia and the world]
- Singapore is leading the world’s technology for water recycling
- … countries [and cities] such as Singapore and Namibia, towns in Texas and California [and Perth, are already drinking recycled effluent i.e. treated sewage water]
Water Recycling Stats & Facts
- 15 Facts About Water Recycling (seametrics.com)