make up water for cooling tower

I'd be careful about borrowing credit strategies from another rating system, especially if you don't see them in the available Pilot Credits or Innovation Catalog lists specific for CI v4 projects. GBCI has been pretty picky recently about what they'll accept as Innovation strategies, and frequently reference users to the two lists I mentioned for approved strategies. That said, it may be worth paying for a CIR/LI for your specific strategy before going through the trouble of installing and documenting everything only to have it rejected.  These approved strategies may be worth exploring: https://www.usgbc.org/node/7433683?return=/credits/commercial-interiors/v4/innovation-catalog https://www.usgbc.org/node/5475510?return=/credits/commercial-interiors/v4/innovation-catalog For counting the savings for this credit, specifically, you should be able to include the rainwater reuse in your calcs, but it will be a separate justification calculation from the regular Water Use Calculator. Just follow the instructions under the credit language in the Reference Guide, in Step 3 of the Step-By-Step Guidance. You should be able to combine the calcs offline to show overall reduction.