Calculating Chlorine/Peroxide Solution Strength

Calculating Chlorine/Peroxide Solution Strength

Step 1 - Calculate Well Pump Flow Rate

To provide the correct dosing you will need to know the flow rate that your well pump puts out. Use the following steps to determine that rate.
  1. Turn the water on by opening a faucet or other water outlet until the pump turns on.
  2. Turn the water off and wait until the pump has filled the pressure tank and turns off.
  3. Without using any other water, open a faucet and use a 5 gallon bucket or other measurable container to collect and measure all the water that comes out until the pump turns on.
  4. As soon as the pump turns on, immediately close the faucet and time how long, in seconds, the pump runs to refill the pressure tank, stopping when the pump turns off.
  5. Divide the number of gallons measured by the number of seconds, and multiply by 60. This is your pump flow rate in gallons per minute (GPM).

  6. Example: If your pump runs for about 40 seconds, and you collect 5 gallons of water:
5 ÷ 40 = 0.125
0.125 × 60 = 7.5
Your pump flow rate is about 7.5 GPM

Step 2 - Determine Solution Strength

Actual solution strength will vary depending on your water chemistry. Use the chart below to determine the approximate dosage rate you need based on your water test results.Dosage rates - for each ppm of listed contaminant, use the dose corresponding to your oxidation solution
as CL2
Hydrogen Peroxide
as H2O2
IRON1.0 ppm0.5 ppm
MANGANESE2.0 ppm1.0 ppm
HYDROGEN SULFIDE3.0 ppm1.5 ppm
For multiple contaminants, add each individual dosage together to get a total dosage. Add 1 - 2 ppm as a residual to account for fluctuations. Example: If you have 2 ppm iron, 0.5 ppm manganese, and 1 ppm hydrogen sulfide and you were using chlorine, your total dosage would be 2 ppm + 1 ppm + 3 ppm = 6 ppm + 2 ppm residual, for a total dosage of 8 ppm. To determine the solution strength needed to achieve this dosing, multiply the desired dosage × pump flow rate × 1440 (minutes in a day) to get the maximum daily dosage in ppm. Divide that total by the maximum daily injection pump rate (if you have an adjustable rate injection pump, use half the maximum daily rate to allow for easier adjusting), and that will be your solution strength in ppm. This can be divided by 1,000,000 to get solution strength in percentage.

Example: if your desired dosage is 8 ppm, your pump puts out 7.5 GPM, and you are using the popular adjustable Stenner 85MHP17 that has a maximum 17 gallon per day output:
8 × 7.5 × 1440 = 86,400 ppm maximum daily dosage
86400 ÷ 8.5 (half max for adjustable pump) = 10,165 ppm solution strength, or about 1%

Step 3 - Mix Solution

Once you have the desired solution strength, simply mix your solution to produce the desired solution percentage. Divide the strength of your chemical by the desired strength of your solution to get the parts of water to add per part of chemical. As an example, most household liquid bleach contains 5.25% sodium hypochlorite. If you are wanting a 1% solution, 5.25 ÷ 1 = 5.25, so you would use 5.25 parts of water to each part of liquid chlorine bleach.

Step 4 - Inject, Test, and Adjust

With your solution made, begin injection and monitor your results. Check your results at the faucet farthest from the injection pump to ensure complete treatment. With chlorine you can monitor residual chlorine level - if there is no residual increase your solution strength or adjustable pump output rate. If there is more than 1 - 2 ppm residual chlorine reduce your solution strength or adjustable pump output rate. If using hydrogen peroxide you will need to adjust based on any residual contaminants in the water. Continue to make adjustments until the desired treatment is achieved. Please note that 30 minutes of contact time is required to ensure proper treatment. To ensure the proper contact time a contact tank or mixing tank is recommended. Use of the system without one may result in improper or inconsistent treatment.