Temporary potable connection to a permanent irrigation system

I have a LEED Campus project, using permanent irrigation systems fed by rainwater collected in cisterns and pumped. Approx. 1/5th of the irrigated area was built with a potable back-up connection (in the event of drought) for the initial 1-year establishment period. We have been awarded two points for reduced irrigation water (80% reduction) but the cross-connection jeopardizes the two no potable water use credits. Would an Owner letter committing to physically disconnecting the potable line from the irrigation system be acceptable? Seems this would meet the intent of the credits.