Operator terms · Water
What is a water storage tank?
A water storage tank holds treated drinking water so a system can meet changing demand, keep steady pressure, and have a reserve for fire flow and peak use. Elevated tanks also use their height to add pressure to the distribution system.
Last reviewed 2026-08-03
Why systems store water
Demand rises and falls through the day, but a plant runs best at a steady rate. Storage lets the plant fill the tank during low demand and draw it down during peak use, while keeping a reserve for firefighting and emergencies.
Elevated tanks versus ground storage
An elevated tank sits high so its water column adds pressure to the system without a pump running. Ground and standpipe storage hold larger volumes, often paired with pumps to move water into the mains.
Common questions
- Why store treated water?
- To meet peak demand, steady the pressure, and keep a reserve for fire flow.
- How does an elevated tank add pressure?
- Its height creates a water column that pushes pressure into the mains.
- What controls tank filling?
- Level controls, often an altitude valve, stop inflow before the tank overflows.