Off-grid Water Collection, Treatment and Use

I am looking for an entirely self-contained solution to off-grid living.  The source of water will be from rainwater capture only and must serve all domestic needs. Climate is tropical so it has plenty of rain.  Greywater should be either treated and used or treated and disposed safely to the environment.  There will be no sewage due to the composting toilet. Cant have any standing water due to mosquitos.  Cant have any chemical treatment.  Minimal energy use is required as it can only use off-grid power so it will add cost to upgrade power systems.  Can get up to 24V. Must not rely too heavily on mechanical parts as skilled maintenance won't be available and replacement parts will take a long time to get there. What are the best solutions for rainwater collection and treatment, greywater treatment and reuse and the composting toilet?