The question: There is a 650m long tube on a 1 degree incline. At one end of the tube is a pump that alone has a volumetric flow rate of 750 g/min. The fluid in question is water and its a PVC pipe. What diameter does this tube need to be in order to have 25 psi on the top end of the tube? (Water is at room temperature) So far: There is an empirical formula that is only an approximation but i realized that it can't be used in this situation cause the pipe is on an incline and its so long that the mass of the pumped out water will push down on the flow rate. How do you take into consideration friction and the water viscosity? Is this even possible?