This document addresses RAIN foundation's guidelines towards water quality and gives practical guidelines to improve and maintain an acceptable water quality of harvested rainwater for drinking purpose. It describes criteria for water quality of harvested rainwater, placed within the socio-economic and geographical context of RAIN foundation's target countries. The most practical approach to improving and maintaining the quality of harvested rainwater in rural water supply schemes is not to impose a set of unachievable targets, but to insist on adequate measures of quality protection that significantly improve the quality of water, compared with traditional sources.