Biosand Filter Construction Guide affordable point of use drinking water treatment method

Abstract

In Kenya close to 50% of the rural population have access to improved drinking water as a result of limited water infrastructure in the country. Therefore the responsibility of improving a water supply or treating collected water generally falls upon individual households, at least in rural areas. Point-of-Use (POU) water treatment technologies are becoming increasingly prevalent in developing countries. This report documents the design, installation guide, performance evaluation and exhibition of a local affordable plastic biosand filter for POU treatment of domestic drinking water at the household level. Through participatory approach 12 community filter fundies were selected in three western Kenya region irrigation schemes and trained on installation and maintenance of the filter. By considering the market price of the materials, the cost of one filter unit is estimated as Ksh 1500 and when the cost of a safe water storage container is added the cost totals to Ksh 1900. Approximately two months after the fundies were trained; a total of 25 filters had been installed at the household level in the three irrigation schemes from which eight mature filters were randomly selected for turbidity and microbiological monitoring and an extra two filters were randomly selected and only turbidity measurement was done. Additionally guidelines for “proper use” of the filters with eight criteria were considered in the filter performance. Results indicated that 60% of the surveyed filters were properly operated, 20% failed one criterion and 20% failed two of the criteria for proper use. Obtained results suggest that violating the guidelines of proper use could be due to one or more of: (i) a desire for convenience, (ii) the quality of training of the household by the filter installer, and (iii) the level of understanding by the end user. Turbidity removal among the filters was variable, 50% of the filters had feed water with turbidity less than 5 NTU standard which was further reduced in the respective product water sampled. Only 30% of the filters had significant reversal of the turbidly which could be attributed to a switch in water source while the remaining 20% of the filters reduced high turbidity of feed water by close to 50%. For the small sample of seven filters out of the eight that recorded proper used, compliance with WHO guidelines for drinking water quality was poorer than expected. The percentage of filters meeting the WHO’s guideline of zero E. coli cfu/100 mL (WHO 2011) was maintained at 85.7% when feed water is compared to product water while the remaining 14.3% had a reduction of 60% in E. coli count. The obtained filter performance results are for the period when the filters had just matured and for a wet period. Seven months after training the number of filters installed had increased to 38 and the low adoption rate is attributed to the community being used to philanthropic model compared to the entrepreneurship model adopted in this project. It is recommended that both sensitization of the community and another sampling campaign covering a higher number of filters be done during a dry period in the second year of the project to further validate the performance of th