You can fix a time with that person , whose water bottle you are charging daily.
Suppose the person says that he or she will fill the bottle daily before 9am. You tell that person that you will energise it between 9 am to 10 or 10.30 am daily. So he or she can start drinking water after 10.30/11 am.
This is the way i have been doing for more than 20 water containers a day just charging with intention of the container or its image in my mind , requesting energies and keeping it aside.
The time range gives you flexibility in your own schedule. In above case if you miss charging before 10.30am and remember it later , you should still charge it, because the person is supposed to drink through the day…..so he or she would definitely get some energy doses.