Metric — Diarrhoeal Disease Reduction
The change in diarrhoeal-illness incidence attributable to a water intervention.
SDG 3 Good Health & Well-beingSDG 6 Clean Water & SanitationWhat is it?
This metric measures the reduction in diarrhoeal-disease incidence (episodes per person-year, or relative risk) associated with a water-safety intervention.
Why does it matter?
Per the platform’s success principle, outcomes — not activity — are what count. Filters distributed is an input; diarrhoea reduced is the outcome that reflects real improvement.
How does it work?
Incidence is measured in intervention and comparison groups over time; the difference (adjusted for confounders) estimates the intervention’s effect.
Who benefits?
Communities whose real health improves, and program managers who can direct resources to what demonstrably works.
Who may be disadvantaged?
Self-reported diarrhoea is noisy and prone to bias; over-reliance on a soft metric can misdirect funding or overstate success.
What evidence exists?
Meta-analyses report meaningful but variable reductions; the effect depends strongly on baseline risk, adherence, and measurement quality.
What tradeoffs exist?
Rigorous measurement (blinded, objective outcomes) is costly; cheap self-report is feasible but weaker evidence.
Common misconceptions
A reduction in one setting is not a universal constant; transplanting an effect size to a different context is a common error.
What you can do next
Pair this metric with the systematic review to understand why headline reductions should be read cautiously.