This especially applies to the intermittent filter. It would be good to look into what marketing approaches produced the most successful results in demand and uptake of filters. It would be good to know how much project success depends on a focussed marketing campaign versus just word of mouth from satisfied customers, and whether a project could be scaled up to reach more people.
Effectiveness of technician-installed versus client-installed filters
This is important information for the development of the intermittent household filter. Almost always where concrete filters are made, the installation (including sand selection) and training in operation and maintenance is carried out at the house of the client by the technician. This technician explains all the possible problems the client might have with the filter, how to know when to clean the filter and how to do it, what not to do with the filter, etc. NGOs promoting the filters often stress (and with good reason) that proper training and installation is essential. In fact, user issues are usually the root cause to many filter efficiency problems. However, it would be good to know if technician training is absolutely necessary, or whether householders could install their own filter and select their own sand given an instruction leaflet (with or without words). If a large enough sample group could be given training, while an equally large group were just given instructions, bacteriological testing could confirm if there was a statistically significant difference between the two groups. The results may help us understand more about the possibility of scaling up this technology past the micro-enterprise level.