If your talking well pump, theres a grey or black box on the side of the pump, remove the top screws and remove the plastic cover. There,s a bolt there with a spring on it, use a nut driver or a small ratchet and socket to adjust this. I beleive if you turn it clockwise it will increase pressure by lengthening the time that the pump runs, there,s also another bolt with a spring like this one there and this is for your pressure setting to kick the pump on you need to determine wich is wich before you adjust ethier. These spring bolts rest on a set of points and adjust the tension on them, these points adjust your high pressure kick-off, and low pressure kick-on. Hopefully there is a pressure guage on the pump by this box that you can watch when you adjust these, if not i would,nt attempt it without it. If by chance you have a galvanized holding tank without an internal bladder, i would suggest you shut off the water supply to the house and turn the power off to the pump. Then open the closest water outlet to this tank (usually it,s right on the tank). Open it and drain the water out, when the water stops, on the side of the tank are 2 plugs, use a pipe wrench to remove them this will allow the tank to draw air and more water will come out the water outlet you opened before. When the water stops, close the outlet, reinstall the plugs on the tank. Now on the top of the tank you,ll see a valve similar to a tire valve stem on a car, remove the valve core inside that valve, turn the pump power back on and fill the tank until water comes out the valve at the top, replace the valve core and wait for the pump to stop. 1 more thing to do, take a tire guage and check the pressure on that valve, you need 18 to 21 pounds of air pressure for a 40 gallon tank at this valve if it,s lower get a compressor or bicycle pump and add to the tank at the valve to whatever you need, if to much pressure just remove it by pushing in the valve core. Unbladdered or usually galvanized tanks get air in them from using water and filling again over a period of time and this will cut down on water pressure, this process i just explained is called (burping)! The best way to tell when you need to do this is by listening to the pump if it kicks on quicker when running water and shuts off quicker after shutting the water off, its a good indication the holding tank needs burped. hope all this helps.