Can private sector participation (PSP) in the urban piped water sector improve child health? I use child-level data from 39 African countries during 1986-2010 to show that introducing PSP decreases diarrhea among urban-dwelling, under five children by 5.6 percentage points, or 35% of its mean prevalence. PSP also leads to greater reliance on piped water. To attribute causality, I exploit time-variation in the private water market share controlled by African countries' former colonizers. A placebo analysis reveals that PSP does not affect symptoms of respiratory illness in the same children, nor does it affect a rural control group
unaffected by PSP.