Pressure water tanks use compressed air to push water through the system. When you live in a city, the water is automatically at your faucet when you need it. People living outside a city typically have water storage tanks that pump water out when needed. Irrigation systems commonly use pressure tanks so that pumps do not have to be used for low-pressure jobs.
Pressure tanks must be filled above a specific pressure level for you to receive adequate water pressure for your home or irrigation system. Without adequate pressure, your water might trickle out of the faucet, or you might not receive any water at all when you turn on your faucet. You must install a pressure switch between your home and the well. You must continually cycle the well pump so the water is high enough to provide adequate water pressure levels. Ground tanks typically have low water pressure and require more energy to expel the water.
Bladder pressure tanks hold the water inside a bladder or bag. The bag is then surrounded by air. The water never touches the well walls, so the tank does not corrode. Although the tank has a long life, the bladders must be replaced. Fixed-bladder tanks do not allow for the replacement of bladders alone, and the entire tank must be replaced if your bladder breaks.
Because the air is pushing against the water or bladder inside the pressure tank, there is a point where no additional water is available. The tank must be refilled before more water can be pumped out. If a small amount of water remains in the bladder, it can be pushed out at high pressure, causing noise. Water can also be trapped in pockets as the bladder collapses and wrinkles while the water is being pumped out.
Pressure tanks let you pre-charge your tank if you know you are going to use a lot of water. If the pressure is too high, your system will make noise before the pump starts, or the pump will start more frequently and stay on for shorter periods of time. You might get fizzing and air in the tap rather than water.