Is Rainwater Cistern acceptable as LID Techniques?

We have asked a similar question to LEED Coach and received this response:

"Yes, collection and reuse is a permitted LID strategy and would meet the requirements of SSc Rainwater Management. If there is only partial reuse of the required volume for the percentile rain event, this is acceptable as long as the remaining volume is also managed by LID strategies."

Hope that helps.

just this morning GBCI confirmed that rainwater collection from a roof that is stored in a tank is considered "Green Infrastructure". and hence, contributes to credit compliance. 

It would be nice if the "LID" and "GI" terms were removed from the reference guide and they simply listed the compliant rainwater capture strategies.... like the list of compliant onsite renewable energy systems. 

Emily, David, thanks for that guidance! We are working on an urban project seeking to comply with the credit requirements using green roofs and a rainwater collection tank large enough to meet the 90 percentile rainfall volume requirements. The stored rainwater will be used for watercloset/urinal flushing and possibly some irrigation. However, the daily flush water requirement is not enough to use all the rainwater that will be stored (and obviously, no irrigation will be required during the storm event). Have you had any guidance regarding whether the stored rainwater must be used within 24-hours, or if there is a specific timeframe that must be met? Thanks for any guidance.

This reuse within 24-hrs requirements sounds very much like a local code/zoning requirement we encountered for projects in a suburb of Boston. We found that there was no equivalent LEED requirement; it was strictly a local requirement. Our project went on hold, so it hasn't been finalized, but the project ended up expanded the RWH tank to accommodate needs. Our water was going to be used for both the cooling tower and flushing to address the 24-hr reuse and overall water reduction. Our mech engineers will get back to us on emptying the tank during winter season once the project is off hold.