Can Citizen Science using social media inform sanitation planning?

Improving the sanitation situation in a community that relies on on-site sanitation requires information about the quantity and quality of faecal sludge (FS) produced. Existing tools for data collection about FS characteristics are either imprecise or very costly. As information and communication technologies are becoming more available in low-income countries, Citizen Science is becoming an option for the collection of sanitation data. This study used an online survey distributed via social media to predict FS characteristics (Total Solids (TS), Total Suspended Solids (TSS), Volatile Suspended Solids (VSS), Chemical Oxygen Demand (COD) and Sludge Volume Index (SVI)) at 40 households in Blantyre, Malawi. Furthermore, the study investigated whether and how an online survey could yield cost-effective and representative information about the sanitation situation at the household level. Facebook and WhatsApp both introduced a bias towards higher income households as low-income households still lack access to smartphones and internet. WhatsApp (€1.01/reply) was significantly cheaper than Facebook (€3.00/reply) and conventional data generation with household interviewers (€1.47-2.20/reply). Monetary incentives generated more replies than pure social messaging. TSS, VSS and COD were significantly correlated to TS. The slope of the regression line of COD to TS (0.97) was similar to one reported for Uganda (0.88), suggesting that the ratio of COD to TS might be independent of the location. Statistically significant median differences of TS concentrations were found for the survey parameters "system type" and "solid waste", making these parameters candidates for predictors of FS characteristics. The sample size was too small for the other survey parameters to detect any differences statistically. Overall, using social media in a Citizen Science approach appears to be a promising new tool for FS characterization. In the current form, it can probably not replace other data collection tools, but rather complement them as a cost-efficient method to gain an initial assessment. Besides sanitation planning, social media and the Citizen Science approach could be employed for data collection in various fields of development cooperation.