Wells, Sump Pumps and Septic Sewage Systems - artesian well pressure issues

I bought a farmhouse with an artesian well which is great having that hose run 24/7 when horses or the garden need water. The problem is that our sink and shower pressure is low. Could this be because of the overflow? There is a garden hose coming from the basement and goes down the yard and runs into a stream. I was told by the previous owner to never let that hose get blocked or freeze. Are there alternatives to this system? I would like to have a shower that will rinse my hair in less than 10 minutes. Another problem comes when the washer or sink is on. The outside hose shuts off completely. We have to coordinate laundry, showers, truck washing, etc. What can we do?

Please better describe your system. I might not understand you correctly, but it sounds like you are saying the free flowing well is piped directly into the house, and another hose wastes the unused water??? Is this correct? Do you have a pump and pressure tank in this system?

Sounds to me like it's a gravity system that feeds into a pressure tank of some sort and the other hose is the over flow for the tank.