we have a project where the rainwater is captured and used for irrigation. The project team has determined that rainwater harvested from the building´s roof will fully supply all the project´s outdoor water needs. These are some teoretical numbers based on meteorogical and irrigation needs data. The project team decides some possibilities in case of unpredictable extreme drought. The question is - is it possible to connect pipeline of potable water to the rainwater accumulation tank only for cases of unpredictable extreme drought?

Thanks for your help.