## Water Tank Overflow Pipe Design

## Water Tank Overflow Pipe Design

(OP)

I have been tasked to design an overflow pipe for an elevated potable water tank. I have reviewed several sources to make sure that my assumptions regarding inlet and exit losses, pipe flowing full v. venting through pipe assumptions are correct. To date, I have not found a good comprehensive reference, including AWWA and API. Does anyone know of a good reference for the proper design of a water tank overflow pipe?

## RE: Water Tank Overflow Pipe Design

The questions are 1) to can you not allow sufficient head above the pipe to assume it flows full (1.5 x D) or 2) can you not add an anti vortex plate or turn the inlet down etc to reduce the amount of air drawn into the pipe.

There are plenty of methods of increasing the flow into an overflow at minimum head such as adding an overflow weir.

## RE: Water Tank Overflow Pipe Design

Typically, the overflow pipe size would be about the same size as the inlet pipes to the tank. If you're a consultant bidding out a job, overflow pipe sizing can be included with the detailed design of the tank (ie, done by the tank contractor).

## RE: Water Tank Overflow Pipe Design

## RE: Water Tank Overflow Pipe Design

If you check flow rates with a large vertical drop, check absolute pressures along the route. With Bernouli's equation, you can derive physically impossible results.