This brief paper is a write up of the experiences of an evaluation team using PRA tools in an impact evaluation of a community based programme providing drinking water (a MYRADA project in Mysore District, Karnataka State, India). The impact evaluation took place over only two days, but, as the paper highlights, some very pertinent lessons resulted from the experience. Six main tools from the 'PRA bag' were used in the evaluation: 'water system map', 'focus group discussions', 'time allocation drawing', 'seasonality of disease', 'individual interviews' and 'observation walk'. On the basis of these methods (and patient facilitation work by the PRA team), it was revealed that the any first impressions of a 'perfect' drinking water system were, in fact, unfounded. Serious (but rectifiable) flaws in the project - in terms of efficiency and equity of access - were exposed and, as a result, the local community became involved in identifying some remedial actions. This extremely useful, and clearly written, paper concludes with a frank discussion of some of the problems with the use of PRA tools, which according to the author, primarily stem from a poor understanding of group dynamics and good facilitation techniques.