Guest Column | August 4, 2014

Math Solutions: Flow Rate Conversions

Wastewater Dan Theobald

By Daniel Theobald, "Wastewater Dan"

Water Online’s “Math Solutions” series, presented by wastewater consultant and trainer Dan Theobald (“Wastewater Dan”), provides an understanding of the sometimes difficult calculations involved in achieving wastewater operator certification.

Flow data is provided in many units of expression, such as liters or milliliters in the metric system, or gallons in an American system. It may also be provided in many different time increments, including seconds, minutes, hours, or days.

Depending on your calculation using flow, converting the unit or time of expression may be required for an accurate calculation.

Some common flow rate conversion calculations are accessible below:

Calculate/Convert Between Cubic Meters And Gallons

Cubic meters per second (cms) to million gallons per day (MGD):

Calculate/Convert Between Cubic Feet And Gallons

Cubic feet per second (cfs) to million gallons per day (MGD):

Calculate/Convert Between American Used System And Metric System

Gallons per minute (GPM) to liters per minute (L/min):

Calculate/Convert Flow Within The American System

Gallons per minute (GPM) to gallons per day (GPD):

Additional Flow Rate Conversions

This is the flow rate conversion calculations presentation in my series of “Math Solutions” (access the full playlist here). If you have specific wastewater math queries, please submit a question.

About Dan Theobald:

Known in the industry as “Wastewater Dan,” Daniel L. Theobald, proprietor of Environmental Services (, is a professional wastewater and safety consultant/trainer. He has more than 24 years of hands-on industry experience operating many variants of wastewater treatment processing units and is eager to share with others his knowledge about water conservation.

Theobald serves as an active consultant for industries looking to achieve and maintain improved wastewater treatment at reduced cost. He is a Lifetime Member of the Who’s Who Registry of Professionals and holds numerous certifications from wastewater management regulatory boards and professional organizations. Theobald contributed one chapter to the Water Environment Federation’s ( Manual of Practice # 37 (MOP-37), a technical manual resource guide for biological nutrient removal, published in 2013.