South Africa is one of the world’s most water-scarce countries. South Africans know what water shortages look like: taps dry, water restrictions, failing municipal infrastructure and growing competition for water between cities, farms and industry. When there is not enough water to meet everyone’s needs, deciding who has access to water first is not just a technical question – it’s also one of fairness. Read more: Why water rights aren’t enough to fix South Africa’s deeply unequal farming sector Most discussions focus on water scarcity. However, having enough water is only part of the challenge. Water needs to be shared fairly between households, farmers, businesses and the environment. This raises a difficult question: what does “fair” actually mean?Municipalities have a legal duty to ensure everyone has equal access to water for their basic daily needs. However, equal does not always mean equitable. Giving a wealthy suburb and a struggling farming community the same amount of water may be equal, but it is not necessarily equitable if one community depends on that water to grow food and earn a living while the other uses it to fill a swimming pool.We are a transdisciplinary team of water researchers who set out to discover what we mean by equality and equity in water. We wanted to find ways to define and manage these concepts to help water services authorities. Ultimately, we wanted to come up with a way to make sure that everyone in South Africa gets their fair share of water. We looked at all the research into water equality and equity and then interviewed and surveyed people working in the local water sector. Read more: The lack of water in South Africa is the result of a long history of injustice – and legislation should start there Our research found that equality and equity in water had different meanings for different people. We discovered that this has made it difficult for local water authorities to implement the ideals and to monitor the consequences of their actions. For example, the people we interviewed said the real issue was not that water is scarce, but rather that water is not shared fairly. We argue that water equity must be based on human rights, social justice and local contexts. This is important, because focusing on access to water for basic needs is not enough to reduce inequality and inequity. Instead, water equity promotes the adoption of both the human rights and social justice approaches.Three principles for sharing water fairlyHuman rights are not just for people. When we talk about the human right to water, we usually think of drinking and bathing. While the United Nations formally recognised this right in 2010, water equity goes further. It includes ecological integrity, the idea that nature itself has a legal right to water. If we pump a river dry for irrigation or industry, the river’s ecosystem dies, which eventually destroys the water source for the people living downstream and all of the elements that depend on that river for life – they have rights too.Social justice: this can be split into two parts, namely procedural equity and distributive equity. Procedural equity is about the process – how decisions regarding water are made. For example, who gets to say how decisions about water are made? Is the information about water easy to understand, or is it hidden behind technical jargon? Distributive equity is about the outcome. It looks at how the benefits (such as water for agriculture) and the burdens (like the cost of fixing pipes or the pollution from a factory) are shared. Context: this involves taking into consideration the unique history, culture and socio-politics of a place. What water fairness means in practiceA strength of the water equity concept is that it can change over time. For example, as we learn more about climate change and become better at predicting and responding to hazards, our ideas about what is “fair” in the way water is shared may also change.We also have to think about fairness between generations. The way we use water today should not leave today’s people or future generations with nothing but dry riverbeds. This is what sustainable development is: managing water not just for ourselves, but for the well-being of future generations. Read more: Crisis proofing South Africa’s water security If we ignore the past and the inequalities it created, decisions about water can continue to leave disadvantaged people behind. If communities are not listened to, water can remain in the hands of the most powerful rather than reaching the people who need it most. This can leave people without enough water and damage the rivers and natural systems we all depend on.South Africa shows how difficult this is to fix. Under apartheid, many Black South Africans were deliberately denied adequate access to water. After 1994, the government introduced new laws saying that water must first provide for people’s basic needs, such as drinking and washing, and keep rivers healthy. Only after that should water be available for farming and industry. But putting these ideas into practice has proved difficult, and many people still do not have fair access to water.What needs to happen nextMaking access to water fair requires governments, scientists and communities to work together. This will become more difficult as climate change makes water supplies less reliable.Decisions about water therefore need to consider who has access, who does not, and who has the political authority to decide how water is used. Based on our research, we think these steps must be taken:Put participation into practice: Move beyond good laws by creating local water management bodies that give communities a real say in decisions and hold leaders accountable.Change how we think about water: Treat water as essential to life and human well-being, not simply as something to be bought and sold.Learn and work together: Create ways for governments, scientists and communities to share knowledge and develop solutions together.Focus on people and authority: Recognise that water management is not only about infrastructure such as pipes and pumps, but also about who gets water, who makes decisions and whether access is fair.Reduce inequality: Make sure that people with poor access to water are the priority and that they have enough water for all their needs.This research was funded by the uMngeni-uThukela Water Chair in Water Resources Research and Innovation. This research was funded by Umgeni WaterRichard Meissner receives funding from the National Research Foundation (NRF).