Wastewater irrigation is an economical and high-in-nutrients option for even the poorest farmers. But, if untreated, the consequences for our health and the environment can be catastrophic. Discover the techniques that could transform agriculture as we know it, offering perhaps the most sustainable and efficient use of resources available today.
It’s not uncommon to see a Rwandan farmer at work tilling the land by hoe. Motorized engines are only slowly starting to be introduced into the country. The small parcels growing bananas, maize, sweet potatoes or even cassava roots that dominate the agricultural landscape belong to smallholders living off their land. In Rwanda, like many other developing countries, most of the produce is consumed domestically, but the country has high hopes for the future. An ambitious government initiative to reform the agriculture sector, known as Vision 2020, is leading the way for change. But to be successful, it must first address the water challenge.
For centuries, water has been the deciding factor between plentiful food and hunger or starvation. Irrigation emerged as a way for humanity to take control over the elements, reducing risk and increasing efficiency. Today, a staggering 70 % of the world’s freshwater resources are used in agriculture, with irrigation taking the largest share. Yet, surprisingly, only 20 % of farmlands are irrigated. These, however, supply 40 % of the world’s food – a testament to the groundbreaking impact of irrigation. On a more somber note, these figures are also a stark reminder of the insecurity that still pervades the sector.
Managing scarce resources
By 2050, when the population reaches nine billion, we will need to produce 60 % more to feed everyone, according to the Food and Agriculture Organization (FAO). To grow more, we need to irrigate more, but the Organisation for Economic Cooperation and Development (OECD) tells us that, by then, the strain on our water resources will have increased by an astounding 55 %.
Although there is enough water to meet this demand, overconsumption and the consequences of climate change can lead to water scarcity, land degradation and food shortage, especially in the least developed regions. Empowering farmers to better manage water is vital. If not, the poorest will suffer. Something needs to change and waste could hold the answer.
The great majority of effluents and wastewater flow back into nature without being treated or reused, which pollutes the environment. One of the targets of the United Nations Sustainable Development Goals (SDG 6) is to halve the proportion of untreated wastewater and increase recycling and safe reuse – the theme of this year’s World Water Day. And what better way to use it than in one of the most water-demanding sectors : agriculture.
Water technology solutions
Wastewater ticks both the sustainability and efficiency boxes, but it’s not an innovative breakthrough. The truth is that for many rural communities, especially in developing countries, sewage and wastewater are often the only source of water for irrigation. Even when other options are available, small farmers value its high nutrient content, which lowers or even removes the need for costly fertilizers. This practice has become essential to the livelihoods of many poor people in Asia, Latin America and Africa, including Rwanda. But there is a darker side. If wastewater is not treated before reuse, it can contaminate the crops, surrounding land and water supplies. The health risk to farmers, nearby communities and consumers could be catastrophic.
“Luckily, today we have the technology to remove almost all contaminants from wastewater so that it’s safe for use,” says Naty Barak, Chair of the ISO technical committee on water reuse (ISO/TC 282). “But this must be done according to strict and clear guidelines, so standards are essential.”
To respond to this need, ISO has developed ISO 16075 on the safe use of treated wastewater for irrigation. The four-part standard covers issues like design, materials, construction, performance and monitoring to help farmers put in place treated wastewater projects.
“ISO 16075 was designed with farmers in mind,” explains Barak. “For example, here you will find answers to practical questions around water quality, the types of crops that can be irrigated, risks you should be aware of and the necessary main components like pipeline networks and reservoirs, and much more. The standard will help you make the most of this nutrient-rich resource, while improving yours and your workers’ safety and keeping pathogens at bay.”
Rwanda is just one of many countries for which untreated water is a problem. The country lacks technology for water retention. Its landscape is mountainous, which means that flooding and soil erosion are common. Together with increased urbanization, these factors contribute to the pollution of rivers and other water resources.
“We have a lot to gain from ISO 16075,” says Raymond Murenzi, Director General of the Rwandan Standards Board (RSB), the ISO member for the country. “Since 2011, RSB has been approached by small and medium-sized businesses asking us for guidance on wastewater irrigation. They want to know how to keep the environment and workers safe, but also about practical issues like the type of crops that can take reused water or maintenance instructions for irrigation systems. This is exactly the type of answers they will find in ISO 16075, therefore today we are seriously investigating the application of this standard in our country.”
For Murenzi, use of ISO 16075 will support the country’s vision for locally produced crops to conform to good international practice. “The standard will help us increase our exports, create more jobs and keep our own people and environment safe. And the benefits don’t just apply to agriculture. Wastewater can also be used for landscape areas and gardens, and even industry. It’s a huge win for the country, but also for the region. We think that other African countries will benefit from our experience.”
For developing countries like Rwanda, International Standards are a powerful way of making best practice and solutions accessible to everyone. But the story doesn’t end here. If you are now convinced that wastewater is an efficient and sustainable option, keep reading because it gets better.
Not all created equal
When it comes to irrigation, there are many techniques available. Today, 80 % of irrigation is done by flooding. This method is one of the oldest in humanity’s arsenal, but also one of the most wasteful. It involves taking water to a field by ditch or pipe so that it flows over the ground and down to the crop. In some cases, as much as half of the water may be lost to evaporation and runoff. Its attractiveness is that it is widely considered a cheap and low-tech option, though, in the long-term, it is neither efficient nor sustainable.
“Flood irrigation depletes and contaminates aquifers, uses an excessive amount of chemicals and increases the release of greenhouse gas emissions, which contributes to climate change. It’s also not the best solution when it comes to wastewater reuse, because of the bigger chance of contamination as it’s spread widely on the land,” says Barak.
Unlike flooding, drip irrigation targets the plant and not the soil. The technique uses drippers or emitters to slowly release water packed with nutrients in a steady and uniform flow directly to the roots, one drop at a time. “It makes sense,” says Barak, “you avoid overwatering, make the most of your resources and save on fertilizers.”
The power couple
According to Barak, Israel has been working on drip irrigation for about 50 years as farmers were struggling to grow crops in the desert. It was the most efficient way to produce more with less and has since been successfully tried and tested with open-field crops, orchards, vineyards and many other farmland areas.
“There is a misconception that drip irrigation is expensive. It can be done with very simple technology, just like it can be done with very complex machinery. So it’s an option that is open to all, but not everyone knows this, and this has been perhaps the biggest barrier to its adoption all these years,” explains Barak.
Now picture drip irrigation paired with treated wastewater – it’s a power couple. In Israel, treated water is used for about 50 % of irrigation, according to the OECD. Both techniques were meant for each other.
Smallholder farmers in rural areas in the developing world have the most to gain from drip irrigation, but a lack of awareness, knowledge and technology are putting up barriers to its adoption. These are exactly the types of issues that standards can help with. Standardizing technology also makes it more accessible and competitive, which reduces cost. ISO has taken a first step with a recently published International Workshop Agreement (IWA) on drip irrigation. For Barak, this IWA will empower more people to understand its potential.
Wastewater reuse and drip irrigation are solid steps in the right direction towards a more sustainable approach to agriculture. “Together, they can help resolve food security, water scarcity, energy cost and depletion of arable land, and even contribute to poverty alleviation, gender equality and urbanization,” says Barak.
Building a sustainable solution
The message hasn’t been lost in Rwanda. Since the launch of Vision 2020, the country has been putting an emphasis on standards in addition to policies, laws and other strategic initiatives to promote “Made in Rwanda” products. In 2013 the government made 281 standards compulsory, of which 127 are for food and agriculture. “We want to create a solid standardization culture in our country to boost exports of local products. For example, we believe that standards and technical regulations for agricultural mechanization will encourage the use of farming technology,” says Murenzi.
Looking ahead to the future, we expect technology to keep evolving, from the development of nutrients, pest control agents and farm equipment to the use of computational technology combined with geolocation devices (known as “precision agriculture”), which will radically change the way our crops are managed. All of these will require standards to increase uptake and ensure quality and safety. As we advance into the next era of agriculture, technological development must continue to be the basis for sustainable crop production. For one thing remains certain : sustainability will be key, if agriculture is to have a future at all.
- Water reuse
- Guidelines for treated wastewater use for irrigation projectsPart 1: The basis of a reuse project for irrigation
- Guidelines for treated wastewater use for irrigation projectsPart 2: Development of the project
- Guidelines for treated wastewater use for irrigation projectsPart 3: Components of a reuse project for irrigation
- Guidelines for treated wastewater use for irrigation projectsPart 4: Monitoring