The first proponents of ecosan systems had a strong focus on increasing agricultural productivity (via the reuse of excreta as fertilizers) and thus improving the nutritional status of the people at the same time as providing them with safe sanitation. Disease reduction was meant to be achieved not only by reducing infections transmitted via the fecal–oral route but also by reducing malnutrition in children. This link between WASH, nutrition, a disease called environmental enteropathy (or tropical enteropathy) as well as stunted growth of children has risen to the top of the agenda of the WASH sector since about 2013.
Agricultural trials around the world have shown measurable benefits of using treated excreta in agriculture as a fertilizer and soil conditioner. This applies in particular to the use of urine. Reuse trials in Zimbabwe showed positive results for using urine on green, leafy plants such as spinach or maize as well as fruit trees. Another study in Finland indicated that the use of urine and the use of urine and wood ash "could produce 27% and 10% more red beet root biomass". Urine has been proven in many studies to be a valuable, relatively easy to handle fertilizer, containing nitrogen, phosphorus, potassium and important micro-nutrients.