Wisely planned, a dependable water well can supply all the water you need now and into the future. A rule of thumb is to allow between 75 to 150 gallons per person per day. You need to take into account the peak demand, for example when there may be extra guests for holidays and weekends. Outside use of water can pose much greater demands. You need to calculate the required well yield if your well is needed for additional water uses such as swimming pools, irrigation, fire protection, heating & cooling, etc.