Explanation
The Water Efficiency Credit, Indoor Water Use Reduction aims to reduce indoor water consumption by installing water-efficient fixtures and fittings, such as faucets, showerheads, toilets, and urinals1. A commercial dishwasher that is ENERGY STAR labeled or performance equivalent would help reduce the water use for dishwashing, which is one of the process water uses included in the credit calculation2. A standard garbage disposal would not reduce water use, but rather increase it. An electronic submeter at the domestic water supply pipe to the building would help measure and monitor water use, but not directly reduce it. An open-loop HVAC system that discharges potable cooling water to a nearby lake would waste a lot of water and potentially harm the environment.
References:
* Indoor Water Use Reduction
* "Maximizing Water Efficiency in Commercial Buildings: Understanding LEED BD+C Water Efficiency Credits"