The sustainable Development Goals (SDGs) were formally accepted by the United Nations (UN) General Assembly on September 5, 2015, paving the way for a sustained, unified development effort on a global scale, leaving the millennium development goals (MDGs) in the dust. They are a collection of 17 goals that are anticipated to affect global social, economic and environmental policy through 2030. The sixth Sustainable Development Goal (SDG) is to ensure that everyone has access to safe, clean water. Everyone has the right to healthy, adequate, physically accessible and affordable water for household use under the right to water security (UN 2015). Although the MDGs have made progress, the goal of improving basic sanitation through access to latrines and sanitary waste collection remains unmet. In addition, the population predictions of nine billion people by 2050 imply that more work remains to be done. SDG-6 performance and its implications on other SDGs are influenced by a variety of factors at various geographical and temporal dimensions. Significantly, the actuality of SDG-6 is defined by natural limits, regulations and ethnic identities (UN 2015).

Water is a limited resource, and increased demand causes water stress, resulting from water accessibility, need and water quality. These challenges are caused by expanding human population and per capita water consumption, increasing urbanisation, the consequences of climate change, the need for additional irrigation water to boost food production and environmental needs for environmental preservation and biodiversity. While climate change impacts water ecosystems and water resource accessibility, socioeconomic factors increase water demand and degrade water sources (Komarulzaman et al. 2017). Briefly, SDG-6 includes local water supply objectives and governance and technologically focused objectives. Achieving the objectives of SDG-6 is essential not just for water-related concerns but also for other SDGs such as SDG-2 on zero waste and SDG-14 on life below water, as well as for the future of the Earth. Clean water is vital not just for humanity but also for flora, fauna and other associated sustainable development initiatives. Sustainable development necessitates the reduction of waste and the recycling of as much water as feasible through the use of a circular system (Gulseven and Mostert 2017). The agenda recognised the need for clean water and proper sanitation for human rights. Clean water is linked to all aspects of life, including food, nutrition, illnesses and poverty reduction. It contributes to promoting sustainable economic growth and the preservation of the planet’s biosphere. SDG-6 defines eight global targets. These are all essential elements that are included in SDG-6. These targets are universally accepted, but all governments ensure the implementation of the targets according to their national liabilities (Alshomali and Gulseven 2020). In line with “Transforming Our World: The 2030 Agenda for Sustainable Development” by the UN, the eight main targets of SDG-6 are illustrated in Fig. 8.1. These targets are categorised under two headings: main targets and implementation targets. The main targets of SDG-6 are illustrated from 6.1 to 6.6, whereas the implementation targets are 6.A and 6.B.

Fig. 8.1
figure 1

Eight targets of SDG-6. (United Nations 2021)

So far, the millennium development goals have aided in mobilising the globe to enhance access to clean water and sanitation. By 2015, hundreds of thousands of people have acquired better water and sanitation access. From 2000 to 2015, the percentage of the world’s population that used better sanitation climbed from 59% to 68%. This indicates that in 2015, 4.9 billion people worldwide had access to better sanitation (UN 2016). Notwithstanding, there is still a long way to go for hundreds of thousands of people who do not have access. In 2020, slightly more than half (54%) of the world’s population will access adequately managed sanitation. Yet, it’s alarming that nearly one-half of the population does not. Around 6% of the population does not have access to sanitation and must practice open defecation (Ritchie and Roser 2021). SDG-6 substantially boosts the degree of expectation for the water sector, asking for universal access to safe water and sanitation while addressing challenges of water quality and shortage concerns over the next 15 years to balance the demands of the environment, energy, communities, agriculture and industry (Leigland et al. 2016).

On the one hand, poor sanitation results in financial damages due to the direct expenses of curing sanitation-related diseases and lost money due to diminished or lost production. Furthermore, poor sanitation costs time and effort owing to inaccessible or inadequate sanitation facilities, reduced product quality due to poor water quality, lower tourism income and more clean-up expenses. As a result, it is undeniable that increased sanitation significantly influences people’s health and the overall economy (Van Minh and Hung 2011). On the other hand, the world will not fulfil the SDGs unless the international financial system undergoes significant change. Fulfilling the targets of SDG-6 by 2030 is not possible with the current financing. Meeting SDG goals 6.1 (i.e. ensuring that everybody has access to clean and affordable drinking water by 2030) and 6.2 (i.e. achieving access to adequate and equitable sanitation and hygiene for all and end open defecation, paying special attention to the needs of women and girls and those in vulnerable situations by 2030) is expected to cost around US$150 billion every year (sanitation and hygiene for all in a fair manner). Additional SDG-6 objectives such as protecting water-related ecosystems, minimising water pollution and adopting integrated water resource management will cost significantly more; total global WSS infrastructure development needs are expected to reach US$6.7 and US$22.6 trillion by 2030 and 2050 respectively. Although the most immediate requirements are in the Global South, high-income nations are also suffering from severe deficits; the USA, for example, is expected to require US$1 trillion in water supply and sanitation (WSS) investment over the next 20 years (McDonald et al. 2021).

Goal 6 of the Sustainable Development Goals is to guarantee that everyone has access to clean drinking water and sanitation by 2030, at the cost of around $150 billion annually. There exist a few funding sources. One alternative is private finance in the form of direct equity investment from private water firms and commercial bank credit. According to a study, private investments in water and sanitation have not materialised as expected due to the industry’s risk-return profile. Private investors regard water and sanitation as “too complex”, with inadequately attractive returns. An undiscovered resource of public funds, public banks, is one option for filling the financial gap for water supply and sanitation. Even though there are about 900 public banks globally, with assets totalling $49 trillion, academic studies and mainstream policy institutions such as the World Bank have been widely ignored as a key source of water and sanitation funding (McDonald et al. 2021). Therefore, SDG-6 has its challenges as it has its targets. SDG-6 must overcome its challenges to achieve its goal to “ensure the availability and sustainable management of water and sanitation for all” (Katila et al. 2019). Sadly, the water industry is failing to fulfil its targets, and studies imply that SDG-6 will face three main challenges (Alshomali and Gulseven 2020):

  1. 1.

    Finance: Since finance is the key enabler in project implementation, it is the most crucial challenge among the others. Unfortunately, the water development industry requires a vast number of financial resources and financial stability for sustainability. The lack of financial resources in underdeveloped countries makes it even more important to be careful while using existing financial resources to achieve rapid growth in the water industry. Additionally, investments in the water development industry have social and environmental advantages as well as economic ones.

  2. 2.

    Capacity Building: Progressively, successful governments create formal and informal institutions to achieve their goals. Unfortunately, in countries with problems with accessing and managing water resources, in Sub-Saharan Africa, Asia and Southeast Asia, there is a severe lack of capability and execution in water-related problems. These parts of the world are at the top of the human shortages of essential needs such as agriculture, safe drinking water, sanitation and risks related to water impacts, water waste and recycling. Sadly, these countries have been experiencing these concerns for decades.

  3. 3.

    Governance: In many industries, successful and fair governance is critical, but it is especially critical in the water development industry. Many of the developing countries are still coping with internal problems such as conflicts and public health-related problems. Also, their governance structures are not stable. Efficient water management requires political stability, institutional rules, administrative management, wise decision-making and related implementations. These gaps can be solved by the government using data accountability.

SDG-6 is critical to achieving sustainable development, as access to safe drinking water and adequate sanitation are human rights (UN-Water 2021). The availability of these services, especially water and soap for handwashing, is critical to human health and well-being. They are necessary for improving nutrition, preventing disease and providing healthcare, as well as guaranteeing the smooth operation of schools, workplaces and political institutions, as well as disadvantaged and marginalised groups’ full involvement in society. The evidence for the negative health effects of inadequate water and sanitation is overwhelming. Poor water and sanitation can lead to a wide range of severe diseases, such as diarrhoea (Howard et al. 2016). In 2017, approximately 1.2 million people died as a result of contaminated water sources, equivalent to 2.2% of all deaths worldwide (Ritchie and Roser 2021).

As mentioned in the recent Summary Progress Update for SDG-6 (UN-Water 2021), acceleration in future action depends on several factors. One of the main bottlenecks is that due to policy and institutional disintegration between different levels, sectors and actors, decisions are taken in one area, or the sector usually falls short of considering the impacts on water quality and availability in other areas. Such fragmentation along with funding gaps and lack of data and information sharing across sectors and borders result in problems in informed decision-making. Furthermore, the implementation of SDG-6 targets is slowed by institutional and human capacity deficiencies, particularly at the local government and water and sanitation provider levels, as well as inadequate infrastructure and governance models. Five accelerators to drive action at a larger scale were proposed to overcome the problems. Optimising finance, improving data and information, capacity development, fostering innovation and effective governance are all needed for delivering SDG-6 results for the future.

There is also a change needed in three professional perspectives that guide water policy. These are economics, management and engineering (Sadoff et al. 2020). Economics should not treat water resources as abundant resources to minimise the costs of its provision. Economics as a discipline should acknowledge the value of water as the scarce key resource and not the capital that is required for its provision. Water engineering also needs to be revised in a way that needs and goals-based perspectives replace the linear and centralised approach to water engineering. This means that by using the existing technology, water engineers should design wastewater recycling systems and differentiate between the sources of water, its costs and qualities to utilise each for certain needs and goals better. “Water engineering needs to move beyond the concepts of reliability and optimality, which evaluate designs over a narrow set of objectives and possible future conditions, to focus on robustness and flexibility in the face of uncertainty” (Sadoff et al. 2020). Finally, water management must increase its capacity to deal with complexity and trade-offs. Adaptive and integrated water management is required in an uncertain environment to account for interconnections, changes and potential surprises. Integrated techniques help identify and minimise trade-offs, as well as the unravelling of unforeseen consequences. They also help promote inclusiveness in water management, as different stakeholders from different sectors at all scales are brought together.

Finally, in line with the impacts of the recent COVID-19 outbreak, acknowledging that millions of people lack access to clean water for sanitation, there is an urgent need for major investments in infrastructure and governance of water provisioning to ensure public health and increase resilience for transmissible diseases and virus outbreaks.

8.1 Companies and Use Cases

Table 8.1 presents the business models of 36 companies and use cases that employ emerging technologies and create value in SDG-6. We should highlight that one use case can be related to more than one SDG and it can make use of multiple emerging technologies. In the left column, we present the company name, the origin country, related SDGs and emerging technologies that are included. The companies and use cases are listed alphabetically.Footnote 1

Table 8.1 Companies and use cases in SDG-6