Harvest Rain Water for Toilet Water

According to Google, toilets account for anywhere between 20 to 40 percent of household water consumption. Given that we waste clean, otherwise drinkable water flushing our toilets, it should come as no surprise that many people harvest rainwater for toilets and other household purposes where potable water isn't necessary.

The author of this howto walks us through the setup of a rainwater-to-toilet system, while sharing his reasons for doing so:

While it doesn't come close to making up for our gas-guzzling, high-consuming lifestyles, rain harvesting does have a positive impact on our environment. Domestic potable water collection requires effort, energy, and chemicals for purification and transport...
Your house is an "impermeable surface". Rain would otherwise hit the ground where your house is and soak into the underground water table or enter a natural stream. Instead, rainfall from the roofs of many urban homes is tied into the sewer system. During periods of heavy rain, this storm surge from houses, parking lots, and streets into the sewer system can max out treatment capacity, causing raw sewage to flow out untreated into waterways. Harvesting some of this storm surge can reduce peak demands on our water treatment facilities.
Besides the more important environmental issues, most of us in urban areas pay for domestic potable water. I have calculated that each flush of the rainwater toilet (1.6 gallons) saves me just over 1 cent. Costing less than $100 to install, this system will pay for itself over the years.
Also, I have the satisfaction of a small level of self-sufficiency from an urban lifestyle otherwise dependant on society for survival.
The guide covers the details of rainwater collection, a formula for calculating your harvest potential, detailed pictures of the entire setup (including how to mesh the rainwater system to standard toilet plumbing via selector valve, enabling the toilet to run off of either system) as well as a breakdown of parts and costs for the project.