For years, we at WSUP have believed this to our core. We’ve seen how the absence of safe water and sanitation quietly chips away at human health, dignity, and opportunity, especially in overcrowded urban settlements where families live on the margins. Now, thanks to groundbreaking new research, we have compelling scientific evidence that goes far beyond anecdote or intuition. The message is clear: urban sanitation has the power to transform a child’s life.
A landmark discovery in Mozambique
In Maputo, Mozambique, a city where more than half the population lives in low-income neighbourhoods without access to basic services, a major sanitation trial funded by the Gates Foundation has revealed remarkable findings.
The Maputo Sanitation (MapSan) Trial, one of the first of its kind to evaluate long-term child health outcomes in an urban setting, examined the impact of providing safe, non-sewered sanitation systems to low-income households. What it found could reshape how cities and funders view the role of sanitation in child development: Significant reduction in stunting when children accessed improved sanitation within their first 1,000 days of life and reduced exposure to harmful pathogens linked to poor sanitation and faecal contamination.
You can read the preprints of the study here:
- Effects of urban sanitation upgrades on enteric pathogen exposure
- Effects of urban sanitation upgrades on child growth
The first 1,000 Days: Why they matter
The science is clear: the first 1,000 days of a child’s life from conception to age two are the most critical for physical and cognitive development. Poor sanitation during this period doesn’t just cause diarrhoea or infections. It stunts growth, impairs brain development, and can irreversibly limit a child’s potential.
At WSUP, this evidence affirms what we’ve long seen in our work: early-years access to water, sanitation, and hygiene (WASH) is not optional—it’s essential. Not just for survival, but for building stronger, smarter, more resilient communities.
WSUP’s big bet: Early-years WASH access
This research has inspired one of our Big Initiatives for 2025–2030: scaling early-years WASH in the world’s fastest-growing, underserved cities. Over the next five years, we will:
- Partner with utilities and municipalities to bring clean water and safe, child-friendly sanitation closer to homes
- Promote hygiene behaviours in maternal health clinics and birth centres to reduce infections for newborns and mothers
- Advocate for urban policies that treat WASH as a child health intervention, not just an infrastructure issue
- Work with schools and childcare centres to ensure access to proper toilets, clean water, and menstrual health education
We’re focusing where the need is greatest: low-income, high-density communities, where stunting, school absenteeism, and health inequalities are most severe.
Why this matters to you
For funders, development partners, and city leaders: the opportunity here is enormous.
- Want to improve child health outcomes at scale? Invest in early-years WASH.
- Want to reduce gender inequality? Support safe sanitation for women and girls.
- Want to build more climate-resilient cities? Strengthen the infrastructure that protects the most vulnerable.
- Want impact that lasts generations? Start with children and start early.
Let’s make it happen
The MapSan Trial has shown us what’s possible. Now, it’s time to turn evidence into action.
We’re inviting partners, governments, donors, private sector leaders, and community organisations, to join us in transforming how urban sanitation is delivered, designed, and prioritised. Because when we invest in WASH for young children, we invest in futures, in equity, and in cities that truly work for everyone.
Want to learn more or collaborate with us? Reach out at comms@wsup.com.
Together, we can ensure every child, regardless of where they’re born, gets the safe, healthy start they deserve.