Environmental sustainability is adherence to resource usage that neither depletes the natural environment nor pollutes it beyond its ability to compensate for or replace the changes. For instance, environmentally sustainable garbage disposal introduces waste to the environment at the same rate the garbage is broken down. Environmentally sustainable water use only takes water from aquifers at the same rate it is replenished.
Environmental sustainability is about managing human activity in a way that does not destabilize the natural environment. It is normal for various forms of life to use resources and deposit waste in their environments, but in the natural environment, these are in equilibrium. Organisms, at least in the long term, do not deplete resources nor fill the environment with waste. Nothing can survive if an organism depletes an ecosystem's major food resources, for instance.
Modern human activities are usually unsustainable. The production of modern toilet paper, for instance, often requires extensive logging of hardwoods, which grow back far less quickly than they are cut down. Eventually, toilet paper manufacturers will run out of the trees from which toilet paper is made. Likewise, modern food products come with so much packaging that disposing of all the nonbiodegradable waste has become a problem in many places.