How much HP motor to be fitted for continuous supply

I have dug my borewell till 515 feets after 450 feets I found water. While testing we used five HP motor which gave two inch water flow for 25 mins, afterwards there is continuous flow of 0.75 inch for whole day and if we stop for 1-2 hrs it gives 2 inches water for 15 mins. Please suggest how much HP motor to be fitted for a continuous supply and whether single phase or three phase motor to be fitted?