Enter the precipitation depth (in), the watershed area (acres), and the runoff coefficient (Rv) into the Water Quality Volume Calculator. The calculator will evaluate the Water Quality Volume. 

Water Quality Volume Formula

The following formula is used to calculate the Water Quality Volume. 

WQV = P * A * Rv


  • WQV is the Water Quality Volume (acre-inch)
  • P is the precipitation depth (in) 
  • A is the watershed area (acres) 
  • Rv is the runoff coefficient (Rv) 

How to Calculate Water Quality Volume?

The following steps outline how to calculate the Water Quality Volume.

  1. First, determine the precipitation depth (in).
  2. Next, determine the watershed area (acres). 
  3. Next, determine the runoff coefficient (Rv). 
  4. Next, gather the formula from above = WQV = P * A * Rv.
  5. Finally, calculate the Water Quality Volume.
  6. After inserting the variables and calculating the result, check your answer with the calculator above. 

Example Problem:

Use the following variables as an example problem to test your knowledge.

precipitation depth (in) = .9

watershed area (acres) = 30

runoff coefficient (Rv) = .50

WQV = P * A * Rv =  ?