As COVID-19 threatens cities and regions around the world, one action above all others will help prevent its spread: frequently washing your hands with soap for at least 20 seconds.

But it is hard to wash your hands if you don’t have access to clean water – and 780 million people lack that basic human right. Such inequity affects us all, and this has perhaps never been clearer than now, in the midst of a pandemic.

We must ensure sustainable and equitable water for all, if we are to stem future crises. How? Effective water planning that steps back and looks not just at the infrastructure that conveys water from source to home – but also maps out the watershed that supplies the water and the socio-economic barriers that lead to water insecurity.

In many places, we can’t see this big picture. Instead, we spend billions of dollars on water infrastructure – to ensure safe drinking water, sanitation and hygiene (known as WASH) – and often ignore the rapidly changing watersheds that supply that water. And when we do model watersheds, it is often in broad strokes, considering the water needs of an entire city or region. That makes some inequities invisible – and thus unaddressed in policy.

Photo: Flashpop / Getty Images

Water models that show how water flows from watershed to faucet – and the inequities along the way – can guide policymakers to successful solutions.

Revealing hidden pockets of water insecurity

Take Cambodia’s Stung Chinit watershed, where a half-million residents rely heavily on the river for their livelihoods. A standard water model shows that the region is water secure, meaning the river supplies enough water to meet the needs of the watershed’s communities.

But such models see a community as one “object” – in this case, an estimate of total water demand, calculated by multiplying the number of people in the community by the per capita water use in the region. This generalization misses the nuances of each community, and the inequities hiding within them.

So SEI dug deeper, and surveyed the watershed’s residents on their water needs and challenges. We then fed this into a Water Evaluation And Planning (WEAP) model. The results were clear: some groups of residents are not water secure, even though they live in a water-secure region.

Specifically, some people have to walk 20 minutes a day to find water. This is of course a problem amid today’s pandemic – imagine the burden of constantly having to wash your hands without a nearby water source. But it’s also just a problem, period. Clean, accessible water is a human right, and it is crucial to global health.

Modeling watershed to faucet

The new model in Cambodia arms policymakers with the information necessary to focus their efforts on the most vulnerable. Bolivia is piloting similar WEAP models, which not only identify who is vulnerable but also the environmental characteristics that affect domestic water use such as droughts, irrigation demands, and river flow requirements for fish.

But it’s just a start. Water management policies at the municipal level vary with each watershed, depending on the scale and autonomy of the agencies and institutions governing the water. In other words: Policies will look different in every place. In the Stung Chinit watershed, it could be ensuring upstream users get enough water for domestic use. In other areas, policymakers may find they need to develop ordinances to ensure adequate living conditions, or that they must build new water infrastructure. All will need data to guide the most sustainable solutions; water models that show how water flows from watershed to faucet – and the inequities along the way – can guide policymakers to successful solutions.

When I was little, my mom used to say “la salud comienza por casa” – health starts at home. With Covid 19, we are learning that more than ever. It’s past time to ensure that every home is healthy, starting with a source of clean water.