Water use generally refers to municipal potable water use on the site. It includes the use from fixtures (faucets, toilets, sinks, etc.), the use from equipment (dishwashers, etc.), and the exterior use for landscaping.
Good system design and good specification of products can easily reduce water use by 50% or more. At least one green building certification system requires buildings to be net zero water use.1
There are several ways to get the most out of every drop: water-efficient fixtures and equipment, water-efficient irrigation and landscaping, recycling water so it can be used more than once, and capturing rainwater. You can also purify the water on-site with living machines or advanced septic systems.