Here’s a useful primer on whole-house rainwater catchment systems:

In many areas of the country, a water-conserving household can provide for all its water needs from what it can catch off its roof. If the graywater and potentially the blackwater/humanure is also recycled for landscaping, each home can become an independent and sustainable part of the local ecology. We often speak of living off our annual income of solar energy, so it makes sense that we should try to live off our annual income of rainwater as well.

Does anyone have documentation on DIY blackwater systems?