Hydrogen peroxide and well water systems
How the ppm math works when well owners add hydrogen peroxide to a holding or pressure tank, with a calculator for any tank size.
Some well owners use hydrogen peroxide as part of their well system, either with an injection system set up by a water professional or by adding it to a holding or pressure tank. Either way, the amounts are talked about in parts per million (ppm), and the math is the same as for a pool or hot tub: an 80 gallon tank at 25 ppm takes about 1¼ tablespoons of 35% or about ¼ cup of 12%. This page shows how that math works for your tank.
Work with your system maker and a water professional. Well systems, tanks and equipment vary. The figures here are ppm math and what people describe doing, not a recommendation for your system.
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- Tank charts, 20–1,500 gal
- 12% and 35%
- Printable tank log
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Tank Chart
How much to add to reach each ppm, starting from a reading of zero.
Using 35% hydrogen peroxide
| Target | 20 gal | 40 gal | 80 gal | 120 gal | 500 gal |
|---|---|---|---|---|---|
| 10 ppm | ½ tsp0.1 fl oz | ¾ tsp0.1 fl oz | 1½ tsp0.3 fl oz | 2¼ tsp0.4 fl oz | 3¼ tbsp1.6 fl oz |
| 25 ppm | 1 tsp0.2 fl oz | 2 tsp0.3 fl oz | 1¼ tbsp0.6 fl oz | 2 tbsp1.0 fl oz | ½ cup4.0 fl oz |
| 50 ppm | 2 tsp0.3 fl oz | 1¼ tbsp0.6 fl oz | 2½ tbsp1.3 fl oz | 4 tbsp1.9 fl oz | 1 cup8.1 fl oz |
Starting from zero. If your test strip already shows some peroxide, add only the difference.
Using 12% hydrogen peroxide
| Target | 20 gal | 40 gal | 80 gal | 120 gal | 500 gal |
|---|---|---|---|---|---|
| 10 ppm | 1¼ tsp0.2 fl oz | 2½ tsp0.4 fl oz | 1¾ tbsp0.8 fl oz | 2½ tbsp1.2 fl oz | ⅝ cup5.1 fl oz |
| 25 ppm | 1 tbsp0.5 fl oz | 2 tbsp1.0 fl oz | ¼ cup2.0 fl oz | ⅜ cup3.1 fl oz | 1⅝ cups12.8 fl oz |
| 50 ppm | 2 tbsp1.0 fl oz | ¼ cup2.0 fl oz | ½ cup4.1 fl oz | ¾ cup6.1 fl oz | 3¼ cups25.6 fl oz |
1 tsp ≈ 4.9 mL; 1 tbsp ≈ 14.8 mL; 1 cup = 8 fl oz.
What People Describe Doing
Injection systems
Many well owners use a metering pump and contact tank installed by a water professional, who sets the feed rate for their system.
Holding & pressure tanks
Others add a measured amount to a holding or pressure tank, using the tank’s size and test strips to work out how much.
Testing
People track the level with hydrogen peroxide test strips before and after adding it.
Finding Your Tank Size
20–40 gal
Small pressure tanks
80–120 gal
Larger pressure tanks
300–1,500 gal
Holding and storage tanks
Use the gallon capacity on your tank’s label or spec sheet. Pressure tanks hold less water than their rated size, so check the drawdown figure with your maker.
Tips and Cautions
Check your equipment
Ask your system maker about peroxide with your pump, tank, filters, softener and any other equipment.
One product at a time
Don’t combine peroxide with chlorine or other water products, and never mix them together in a container.
Test, don’t guess
Start low, test, and keep a simple log of the date, reading and amount added.
Handle concentrate carefully
Wear goggles and gloves when you measure 12% or 35%, and measure over a sink with a cup or spoon kept just for peroxide.
Store it safely
Keep bottles capped, cool and dark, labeled, and out of reach of children and pets.
If it splashes
Eyes: rinse with clean water for at least 15 minutes and get medical help. Skin: rinse thoroughly. Follow the SDS first-aid section.
Frequently Asked Questions
How much hydrogen peroxide for an 80 gallon tank?
For about 25 ppm, roughly 1¼ tablespoons of 35% or about ¼ cup of 12%, starting from zero. Use the calculator for your exact tank and target.
What ppm do people use?
The figures people share vary widely depending on their system and what their water professional suggests. The calculator covers 10, 25 and 50 ppm so you can see the math.
Should I use 12% or 35%?
Both reach the same ppm. 35% means smaller amounts to measure and fewer bottles for large tanks; 12% is easier to measure in small amounts.
How do I know how much is in the tank?
Test strips that read 0–100 ppm show the level. Test before adding and again once it has mixed.
Need a different strength? Our dilution calculator works out any mix. See all our guides and calculators.
Free PDF guide
Take the well system guide with you
- Tank charts, 20–1,500 gal
- 12% and 35%
- Printable tank log
4 pages · by email (and text, if you like)
Check your inbox
We sent a download link to . It can take a minute to arrive. Don't see the email? Check your spam or promotions folder.
Disclaimer
Information only, used at your own risk. This page and calculator explain the ppm math and how people describe using hydrogen peroxide with well systems. Wells, tanks and equipment vary, so work with your system maker and a licensed water professional. Results are estimates based on what you enter. You are responsible for how you mix and use hydrogen peroxide.
No product claims. Nothing on this page is a claim about water quality or that hydrogen peroxide treats water or controls any organism. Hydrogen peroxide sold by Bulk Peroxide is not sold or labeled for water treatment.
Handling. Concentrated hydrogen peroxide can cause serious burns to skin and eyes and can damage clothing and surfaces. Follow the product label and Safety Data Sheet, wear protective equipment, and keep it away from children and pets.
Limitation of liability. To the fullest extent permitted by law, Bulk Peroxide disclaims all warranties regarding this information and is not liable for any damages, including damage to wells, tanks, pumps, plumbing or equipment, arising from its use.