Plumbing used to be accomplished with simple tools and materials, combined with a lot of hard work. That is not the case any more. These days, plumbers and the purchasers of plumbing goods and services have a lot more choices and a lot more responsibility when making those choices. We have a responsibility to make our impact on the Earth as friendly as possible, and we all want to save money while doing that.
Some of our most modern choices are really a come-back from the old times. Cisterns and other forms of rainwater capture were standard long before we brought the bathroom inside the house. Now water re-use something to add to your plumbing idea list. Rainwater and storm water systems are often included in modern environmentally conscious plumbing designs. Water collection can be combined with gray water use technology. Consult with your plumbing contractor and you will be able to work out a plan that makes good plumbing sense and good Earth sense as well.