Wardygirl - Just checked with the source (grandma) on your question and she says that you don't need drink it all in one day and it will keep in the fridge. She recommends you have at least 1 large glass in the am and then at least another through the day, especially in the first 3 days.

My mum said she used to drink the whole first batch in the first day and then her second batch would last for 2 days, she would make a 3rd batch that would be gone after 3-4 days then didn't need to worry about drinking it again.

I really hope it helps.