Our project is a 104,000 sq. ft, three-story medical office building. We have designed a rainwater harvesting system with cistern capacity of 15,000 gallons to provide 100% of irrigation needs, an approximate reduction of potable water use for sewage conveyance of nearly 60%, and an overall 40%+ potable water use reduction on an annual basis by collecting 82% of the stormwater that falls on the site . Our question relates to the system control. We could program the controls to call on collected rainwater from the cistern for only irrigation during the summer months. All toilets during the summer months would thus be served by potable water only. We will begin the irrigation season with a quantity of water in the storage tank equivalent to the peak demand that occurs in July, and we can show that rainfall that will be collected during July is greater than the irrigation demand for that same month. While this strategy would ensure that, drop for drop, only rainwater is being used for irrigation, it does not maximize annual potable water savings. The scenario that ensures maximum potable water savings is to always use cistern water when it is available, and to use municipal water as a back up when the cistern can no longer provide collected rainwater. Our objectives are to minimize environmental impact, reduce potable water use at the project overall, and qualify for all of the credits in the "Water Efficiency" category. We would like confirmation that we can earn WEc1.1 and WEc1.2 by demonstrating that the system\'s capacity meets all of the required thresholds on an average monthly and annual basis, ensuring maximum potable water savings. Please note that once the plantings have been established, irrigation demand will decrease, further reducing the opportunity for potable water savings reductions under the controls scenario.