Operator terms · Water
What is a hydropneumatic tank?
A hydropneumatic tank is a pressure tank that holds both water and a cushion of compressed air. The air keeps the water under pressure, so a small system can hold steady pressure and let pumps cycle less often. It is common on small groundwater systems.
Last reviewed 2026-08-03
How it works
The sealed tank is partly water and partly compressed air. The air pushes down on the water, holding it under pressure. As customers use water, the air expands and keeps pressure up until the pump refills the tank.
Why small systems use it
It lets pumps run less often by providing a pressurized reserve, and it smooths out pressure swings. That makes it a common choice for small groundwater systems that do not have an elevated tank.
Common questions
- What is inside a hydropneumatic tank?
- Both water and a cushion of compressed air.
- What does the air do?
- It keeps the water under pressure and steadies system pressure.
- Where is it common?
- On small groundwater systems without an elevated tank.