The online RCAP Resources Library has a variety of resources that are useful to small, rural drinking water and wastewater systems.

Reviewing Old Concepts in the New Year

A Drop of Knowledge E-Newsletter

Reviewing Old Concepts in the New Year

Keeping your math skills fresh may help with daily tasks


by Breanna Detwiler, Communications Director (RCAP)
For some of us math is a distant memory. Our least favorite class that we trudged through in order to graduate.  But despite those bad memories, math is part of the daily job of a water operator. It’s also the #1 thing that operators and aspiring operators fail on the certification exam. Whether you are working towards certification or already operating a system, reviewing math concepts, such as fractions, conversion factors, percentages, area, and volume, will keep your system operating at its best. Operators with a strong math foundation are better able to make split second decisions and determine proper treatment in a moment’s notice.


Worried you are bad at math? Don’t be! You probably know and remember much more than you think.


Let’s review a concept together:

Conversions are essential to making sense of units that don’t match up.  You might find that you purchase a chemical that’s measured in liters instead of the fluid ounces needed for application. Or you might need to calculate the number of gallons in a tank using its dimensions, which requires a conversion from cubic feet to gallons. Conversions can help you make sense of these issues.


Some conversions are weight to volume/volume to units, such as:


1 gallon  =  8.34 pounds     1 cubic foot  =  7.48 gallons

1 PSI  =  2.31 feet head      1 gallon  =  231 cubic inches

1 cu. ft.  =  62.4 pounds      1 acre-feet  =  325,851 gallons


Say you need to determine how much 4 gallons of water weighs in pounds. Since we know 1 gallon= 8.34 pounds we can set up the following equation.


4 gallons        x         8.34 pounds =

1 gallon


Our gallons cancel out so we’re just left with pounds.



4 gallons        x         8.34 pounds33.4 pounds

1 gallon



See, it’s simpler than you remember! For a whole table of formulas and conversions for water treatment click here.


This new year, take a little time to review some basic math concepts that are sure to make your work easier.

Need more math review?


Here are some resources that might help:

  1. Our training calendar lists operator math trainings held by our regional partners across the country. They’ll review math basics and provide tactics for solving problems.
  2. AWWA has a number of books and manuals on math for operators, including Math for Distribution System Operators (2007) and Math for Water Treatment Operators (2007).
  3. Our regional partner, Rural Community Assistance Corporation, has a number of math presentations online and regularly holds online trainings in math.
Got questions for an expert? Submit a question to be answered by one of RCAP’s field staff. Questions can be about technical, managerial, or financial matters in your system. Submit your question at