Imagine a planet where only 2.5% of the world's water is freshwater, a vital but very scarce resource among the 1400 billion cubic kilometers of water the earth contains. Although seawater desalination is progressing, this precious reserve remains our main source of fresh water. This is why unconventional water is emerging as a promising solution to ease the pressure on freshwater reserves.
This approach is particularly relevant for non-food uses, such as automatic watering of green spaces and sports fields. But what exactly is meant by “unconventional water”, and how can it help preserve our drinking water resources?
What is non-conventional water?
Unconventional water refers to alternative water sources that do not come directly from natural freshwater reserves. These sources include:
Treated wastewater: Domestic and industrial wastewater can be treated and reused for non-potable purposes.
Recycled grey water: Slightly used water from sinks, showers and washing machines can be treated and reused.
Reclaimed rainwater: The collection and use of rainwater for irrigation and other non-potable purposes.
Desalinated water: Seawater or brackish water transformed into fresh water using desalination processes.
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Once treated, these resources offer a viable alternative to drinking water for certain uses, reducing the need to draw on freshwater reserves.
Why is non-conventional water developing?
Unconventional water plays a crucial role in sustainable water management. It enables :
Reduce pressure on drinking water resources: unconventional water used to irrigate sports fields and green spaces represents drinking water saved for the essential needs of the population.
Adopting sustainable water management: the use of alternative water sources is part of an integrated approach to water resource management. These resources are becoming essential to meet the challenges of climate change and population growth.
Encouraging innovation and green technologies: Unconventional water treatment and reuse stimulate the development of new technologies and sustainable practices.
Preserving drinking water resources
Reducing demand for drinking water is one of the main advantages of using unconventional water. The use of alternative water sources for irrigation preserves freshwater reserves reserved for essential uses such as human consumption. Collected rainwater is used, for example, to water lawns, gardens and sports fields.
Environmental sustainability
The use of recycled water or reclaimed rainwater promotes more sustainable management of water resources. It's part of an ecological approach that limits waste and reclaims water that would otherwise be discharged into the natural environment. For example, grey water from showers and washbasins can be treated and reused for irrigation, reducing the amount of wastewater discharged into sewage systems.
Improving urban resilience
The use of unconventional water improves the resilience of cities to water shortages. By diversifying water sources, cities can better cope with periods of drought and fluctuations in water availability. Rainwater harvesting systems, for example, can provide a reliable source of water during periods of drought, reducing dependence on traditional water sources.
Challenges and solutions for unconventional water use
Despite its advantages, the use of unconventional water does face certain challenges. However, solutions do exist to overcome these obstacles.
Quality and processing
To be used without health risks, unconventional water used for irrigation must be of sufficient quality. Appropriate treatment systems must be put in place to guarantee health and environmental safety. For example, treated wastewater must be purified to remove contaminants before being used for irrigation. Water treatment technologies such as filtration, ultrafiltration and UV disinfection are commonly used to guarantee water quality.
Infrastructure and costs
Setting up non-conventional water collection, treatment and distribution systems requires investment. However, these costs are offset in the long term by the savings made on drinking water consumption. Rainwater harvesting systems also require initial investment to install storage tanks and distribution systems.
Social acceptance and regulations
Social acceptance and regulation can also pose challenges for the adoption of unconventional water. The public needs to be made aware of the benefits of using unconventional water and reassured about water safety. Awareness campaigns should be conducted to inform the public about the benefits of using rainwater for irrigation, and about compliance with water quality standards and recent regulations that guarantee the sanitary safety of unconventional water.
Case studies: unconventional water success stories from around the world
Singapore: a model of integrated water management
Singapore is an outstanding example of integrated water management, using a combination of potable, recycled and desalinated water to meet its water needs. Singapore's NEWater program recycles wastewater to produce high-quality water used for industrial applications and the irrigation of green spaces. This approach has enabled Singapore to reduce its dependence on imported water, while ensuring a reliable source of water for its residents.
Australia: using rainwater and greywater
In Australia, many cities have adopted rainwater harvesting and grey water reuse systems to irrigate green spaces and sports fields. For example, the city of Melbourne has set up rainwater harvesting systems to water its parks and gardens, thus reducing the demand for drinking water. In addition, grey water treatment systems have been installed in some residential areas to reuse water from showers and sinks for irrigation.
United States: reuse of treated wastewater
In the United States, several cities have adopted the reuse of treated wastewater to irrigate green spaces and sports fields. For example, the city of Los Angeles uses treated wastewater to water its parks and golf courses, thereby reducing the demand for drinking water. In addition, awareness-raising programs have been set up to encourage residents to adopt water conservation practices, such as reusing grey water for irrigation.
France: using rainwater to irrigate tennis courts, an initiative of the French Tennis Federation:
An in-depth climatic study was carried out to determine the water requirements of a clay tennis court. This analysis was used to identify possible solutions, such as rainwater harvesting, to effectively meet these needs.
France: use of treated wastewater for golf course irrigation
Several golf courses located near water treatment plants already use this water source for irrigation. Use is subject to authorization and must meet a number of criteria, including compatibility with the environmental flow of the watercourse fed by the WWTP.
Technologies and innovations for unconventional water use
Rainwater harvesting systems
Rainwater harvesting systems are becoming increasingly popular for irrigating green spaces and sports fields. These systems collect rainwater from roofs and impermeable surfaces, store it in tanks and distribute it for irrigation. Filtration and treatment systems guarantee water quality. For example, sand filters and UV disinfection systems can be used to remove contaminants from rainwater.
Wastewater treatment technologies
Wastewater treatment technologies are always associated with unconventional water reuse. Advanced treatment systems, such as ultrafiltration, reverse osmosis and UV disinfection, are used to purify wastewater and make it safe for irrigation. Ultrafiltration systems use membranes to remove particles and contaminants from water, while UV disinfection systems use ultraviolet light to kill micro-organisms.
Intelligent water management systems
Intelligent water management systems use water meters, sensors and communication technologies to monitor and manage water use in real time. These systems are used to rationalize the watering of green spaces and sports fields, automatically adjusting water frequencies and quantities according to weather conditions and plant needs. Soil moisture sensors are used to measure soil humidity and adjust irrigation accordingly. Connected water meters are used to measure volumes consumed and detect water leaks, thus reducing water wastage.
Towards intelligent water management
The adoption of non-conventional water for watering green spaces and sports fields represents a significant step forward in the preservation of drinking water resources. This innovative approach is part of a broader approach to sustainable water management, essential in the face of current and future climate challenges.
By integrating these practices, local authorities and green space managers are actively contributing to the protection of one of our most precious resources: drinking water. The use of unconventional water, combined with advanced technologies and intelligent water management practices, offers a promising solution for ensuring a sustainable future for our water resources.
In conclusion, unconventional water is a viable and necessary solution for preserving drinking water resources. By adopting sustainable practices and investing in innovative technologies, we can guarantee efficient and responsible water management, ensuring the availability of this essential resource for future generations.
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