SSc6.1 Design Storm Interval

Follow up with the CaGBC, Hi Curtis, I apologize for the delay in getting back to you. For SSc6.1 you need to demonstrate that the tank is sufficiently sized to handle another storm 3 days or 72 hours later to ensure that overflow is not being directed into the municipal system, which would affect credit compliance. However, since you are using this water for toilet flushing you probably would not want the tank to be empty after the three days, which is fine, there just needs to be enough room for the next storm which is how the 72 hours is handled. In terms of the storm frequency and volume of rainfall to use for the water balance this should be taken from local weather data. Hopefully this helps, please do not hesitate to contact me if you have any other questions. Kind regards, ***In addition I spoke with the reviewer and they assured me we could make a case for adjusting the 3 day (72 hour) storm frequency based on our local climate and weather data! Good Luck all!