If you’ve never done this before, it can initially be confusing trying to determine how to dilute chlorine bleach to get 50ppm (parts per million) or whatever disinfection level is needed in your particular situation. Let us give you some insight.
Typical household bleach contains 5.25% chlorine, which is free to react with water during the disinfection process. If you don’t use enough bleach, you may not eliminate bacteria, and if you use too much bleach, you may create a taste and odor problem.
In order to determine how much bleach to add, first you need to read the bottle of bleach you’re using to find out exactly what percent chlorine it contains. Then, you must know the volume of the container being disinfected.
Let’s say your container is a 5 gallon bucket, and your desired ppm level is 50ppm. Here is how you would determine how much bleach to add:
- Multiply 5 gallons x 50ppm
- 5 x (50/1,000,000) = .00025 gallons of chlorine (This is the amount of pure chlorine you would need to add to get 50 ppm.)
- Remember that bleach is only 5.25% chlorine, ie, 1 gallon of bleach = .0525 gallons of chlorine.
- So, in this example, .00025 gallons / 0.0525 = .0048 gallons of bleach.
We’re guessing you don’t want to measure out .0048 gallons of bleach, so let’s convert that into something more manageable.
One gallon has 128 ounces, so if you’re measuring in ounces, multiply .0048 gallons x 128 ounces = .6144 ounces. One gallon is also equal to 16 cups, so if you’re measuring in cups, multiply .0048 gallons x 16 cups = .0768 cups. One gallon equals 256 Tablespoons, so multiply .0048 gallons x 256 tablespoons = 1.23 Tablespoons. Etc, etc, etc. Obviously, the larger container and the higher the chlorine concentration, the larger measuring tool you’ll use, and vice versa. Just Google conversion factors, and you’ll be good to go.
If you are working in metric units, it’s easiest to remember that 1 ppm = 1 milligram/Liter.
Check out our video below on using our chlorine test papers and strips to test chlorine solutions.
And our last tip for today, is to read the bottle of disinfectant carefully for dilution instructions and so forth. For further information on a specific product, you can always visit the EPA’s website, enter the registration number, and view details about the product. Below the details, you will find a PDF with the date the product was registered by the EPA. If there is a list, the PDF at the top of the list will show the most recent approval. If you click on the most recently approved PDF to open it, you can then scroll down to the section that shows the direction for using the product as a sanitizer or disinfectant.
That’s it for today’s lesson!
Here’s a great question asked by one of our clients recently…
“Hi guys, I have received the order of hypochlorite solution, but I have a question with regards to dilution. The instructions I have are to mix this to a 200 parts per million solution. Can you please advise how much hypochlorite solution this would be? And to how much water? Thank you, Crystal”
Thanks for your question Crystal.
Note: For those of you who would just like to know how to quickly calculate cleaning chemical dilution rates and ratios click for the article here
Now let's start talking parts per million and dilution rates.
Our Hypo product label states that for general cleaning you should use at 1 part Hypo to 500 parts water, so for every 500 litres of ready to use solution one litre of Hypo needs to be added. General cleaning is the application we supply our Hypo for primarily but in many specialty applications where sanitising is required a parts per million recommendation or requirement can be requested.
Parts per million with a Hypo solution can be a difficult thing to accurately calculate and measure because by nature the Sodium Hypochlorite level in the concentrated form reduces over time from the point of manufacture. When manufactured the concentration is about 13% but this reduces due to time, exposure etc. For accurate instructions, you are best consulting with whoever is recommending any specific direction as to how best to calculate the correct dilution to avoid any confusion because these matters are often critical in certain applications.
To answer Crystal’s question, it's not as simple as 200 parts Hypo to 1,000,000 parts water (which would be 1:5000) because you have to allow for the starting concentration of Sodium Hypochlorite of 10-13%. Most of the time calculations are made at the 12.5% mark.
You should get your own advice on the initial concentration of the sodium hypochlorite solution you are using.
This is how we work it all out…
To prepare 100 litres of a 200ppm solution from a 12.5% sodium hypochlorite (NaOCI) solution, the following calculations are needed…
She didn't read this blog, and now look...
Here’s the 3 important numbers you need before you start…
1. Final chlorine solution volume = 100 litres = 100,000ml (because 1 litre = 1000ml)
2. Final chlorine solution concentration desired = 200ppm
3. Initial chlorine solution concentration = 12.5% solution = 125,000/1,000,000 which can also be expressed as 125,000 parts per million (ppm) because 1ppm = 1ml in 1,000,000ml
So how much Hypo chlorine solution by volume (ml) do you need to add = ?
• Initial Hypo chlorine solution concentration x Initial Hypo chlorine solution volume (?) = Final chlorine solution volume x Final chlorine solution concentration desired
• 125,000ppm x ? = 100,000ml x 200ppm (Sorry, but a little bit of basic algebra is required)
So to prepare 100 litres of a 200ppm solution of Hypo – Sodium Hypochlorite, dilute 160ml of a 12.5% Sodium Hypochlorite solution with 100 litres water (The actual, technically correct amount of water would actually be 99.84 litres as we would subtract the amount of Hypo we are adding from the amount of ready to use solution required).
Hope this helps, you might find some online calculators through Google to make this easier so you don’t have to work it out each time. And if you have any further questions about dilution or commercial cleaning products please get in touch.
Have a great day.
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It is intended for use by public health units, health care facilities, child care centres, swimming pool operators, and the general public (e.g., for disinfection of wells and homes).
Important: Always add the bleach solution to the water when preparing the solution, not vice versa.
Your results will appear here.
- Always follow safety precautions and the manufacturer's directions when working with concentrated solutions of bleach (sodium hypochlorite). To avoid injury, use appropriate personal protective equipment during handling (read the label and refer to the material safety data sheet).
- Chlorine bleach solution might damage some surfaces (e.g., metals, some plastics) so it is advisable to check with the manufacturer before using.
- For chlorine bleach solution to be effective, a certain amount of contact time with the surface is needed. Contact time varies according to what is being disinfected.
- Never mix chlorine bleach products with other cleaning products, especially glass cleaners, and products containing ammonia or acids such as vinegar. This practice can produce toxic gases which may include chlorine gas - a very toxic gas that can cause severe breathing problems, choking and potentially death.
- To be more effective, clean the surface before using the chlorine bleach solution.
- A bottle of bleach has a shelf life, so check the bottle for an expiry date or check with the manufacturer for the shelf life of the product.
- Do not premix the water and bleach solution, as it loses potency over time.
The calculation performed in this tool is based on the following equation: C1 x V1 = C2 x V2
- C1 is the initial concentration of the bleach (sodium hypochlorite) solution.
- V1 is the volume of the bleach to be diluted with water. This is what you are trying to calculate.
- C2 is the concentration of the diluted bleach solution you are preparing.
- V2 is the volume of bleach solution you are preparing.
Disclaimer
The dilution calculator is provided/being made available by Public Health Ontario without any warranties, express or implied, including fitness for a particular purpose. Public Health Ontario, its directors, employees and agents shall not be liable or responsible to any person for any harm, loss or damage that may arise in any connection with the use of the dilution calculator, including without limitation any direct, indirect, special, third party, or consequential damages.