How Much Water To Store?

[Midnitemo]

i'm only going to have approx 400ltrs in water bob 150ltrs in 25ltr containers and approx 200ltrs of grey outside in a waterbut...750ltrs in total, but i don't think usage is going to be especially high in a bug in stance , i have planned to resuply and dispose of waste daily(situation permiting) early hours of the morning from a local brook 150m away obviously the waste is going elsewhere.