Small gravity flow water systems using small diameter PVC pipe are an increasingly popular technology in the mountains of Phrae Province, Thailand. The systems are appropriate to the needs and capabilities of the rural Thai village users; rural Thai villagers have been able to independently design, finance, and construct systems serving from 10–30 houses. Technical details about the construction, maintenance, and finance of two systems in Ban Nam Jom Village are described. The systems include sedimentation and sand filtration tanks, and also galvanized iron reservoirs. One system, serving 22 houses, was constructed at a cost of US $904.72. Low cost gravity flow water systems are a new technology for accessible mountain areas in countries where cheap PVCpipe is available.