How long will the CDS solution stay active once mixed in the water bottle in the refrigerator with a tight lid or cap? Days, weeks, Months? Thanks for any information.

I am interested in putting the CDS gas in water bottles (with water), and keep them in the refrigerator for a family member that does not live with me. Is there a time frame of how long the CDS will stay active once mixed in the water? I am not able to be at their home to make it daily for them.