sus·tain·able adj \sə-ˈstā-nə-bəl\
a : of, relating to, or being a method of harvesting or using a resource so that the resource is not depleted or permanently damaged <sustainable techniques> <sustainable agriculture>
b : of or relating to a lifestyle involving the use of sustainable methods <sustainable society>
The EPA says sustainability is important to making sure that we have, and will continue to have, the water, materials and resources to protect human health and our environment.