what do we call it when we are able to repeat a process indefinitely without using up or contaminating the resources?

When we are able to repeat a process indefinitely without using up or contaminating the resources, it is known as Renewable Resources .
Explanation:
Renewable resources are the naturally available resources which will replenish to replace the portion of depleted usage and consumption by natural reproduction.One of type of renewable resource is renewable energy including solar, geothermal and wind energy.
These renewable resources are very important part of Earth's natural environment. Water also form a part of renewable source. Water, if carefully used and controlled it's usage in daily life and also given proper treatment then the water is considered as renewable resource