If a storage tank is not tall enough to accept full system pressure without overflowing, what is installed, and how is the flow out of this tank usually described?

• A. Gate Valve
• B. Float Valve
• C. Altitude Valve; Unrestricted
• D. Pressure Relief Valve; Restricted

Answer: (C)

When a storage tank isn’t tall enough to accept the full system pressure without overflowing, you install an altitude valve on the line feeding the tank. This valve acts as a level control: it opens to allow inflow until the water reaches a preset elevation, then it closes to prevent further filling and overflow.

The flow leaving the tank to supply the distribution system is described as unrestricted because the valve regulates only the inflow into the tank. Once water is in the tank, its outflow to the rest of the system isn’t restricted by this valve—the rate is driven by downstream demand and the piping, not by the tank’s fill-control device.