What Chlorine is Used For? Old Chemical Kills New Bugs

Chlorine Bleach Disinfectant Test Strips

Chlorine bleach (sodium hypochlorite) has long been used to remove stains, treat drinking water & disinfect food preparation materials. Many other chemicals are now being used for sanitizing & disinfection but chlorine bleach is cheap, readily available & has found new life as a potent agent against dangerous bugs including viruses such as Ebola & bacteria such as MRSA (methicillin resistant Staphylococcus) & VRE (vancomicin resistant Enterococcus).

For a complete list of important sanitizers & disinfectants with lots of details, see the CDC Guide to Disinfection & Sterilization.

10,000ppm Chlorine Test Strips
(Ebola/MRSA/VRE/C. difficile)

Relatively low concentrations of chlorine,  500-1000ppm, are usually good enough for routine disinfection. However, with the advance of drug resistant microbes such as MRSA (methicillin resistant Staphylococcus) & C. difficile & lethal viruses such as Ebolahigher concentrations are required, to 5000ppm, according to the CDC. This is due to a number of factors but two of the most important are that organic material such as blood & feces reduces the effectiveness of chlorine & the other is that viruses in general can be very difficult to destroy.  As a precaution,  preparing a 10,000ppm chlorine bleach disinfectant solution can address this since enough killing power remains even in the presence of blood or feces. Click on the image of the 10,000ppm color chart below to view a table showing how to view both the 10,000ppm chlorine disinfectant test strips & how to dilute regular store bought bleach.

10000 Chlorine Bleach Disinfectant Test Strips

2000ppm Chlorine Test Strips
Daycare/Nursing Homes

chlorine test strips
chlorine test strips

The 0-2000 ppm version is perhaps the most versatile of all the chlorine bleach test strips. It can be used for routine sanitizer levels for rinsing dishes & utensils, do relatively low level disinfection at home, school, daycare or in nursing homes or be used for higher level disinfection during flu season. The color chart indicates a range of 50-200ppm for basic sanitizing tasks such as a dish or knife rinse solution. A second range, 500-800ppm is highlighted for general purpose disinfection . The color chart shows an upper limit of 2000ppm which is available for those occasions where someone in the household has come down with a cold or minor infection. Click on the image below to see more information on the 0-2000ppm chlorine bleach disinfectant test strip.

200ppm Bleach Test Strips

The most commonly used chlorine test strips, surprisingly, test for relatively low levels, in the range of 100-200ppm. These test strips are used to ensure sanitizing strength levels in rinse water without imparting a taste to food. Dishes  & utensils cleaned in restaurants are dipped into this chlorinated rinse to apply a thin film that can inhibit (not kill) bacterial growth from airborne sources. It is a simple but effective means of keeping common microbes at bay. Click on the image below to see more information on the 0-200ppm chlorine bleach sanitizer test strip.

chlorine test strips
chlorine test strips

10ppm Residual Chlorine Strips
(Water Treatment)

Chlorine test strips
Chlorine test strips

Chlorine bleach is used in many municipal water treatment systems to inhibit microbes & parasites such as amoebae.  Chlorine levels in drinking water are usually so low as to be undetectable except by specific lab tests. Municipal water systems are periodically flushed with higher levels of chlorine & these residual chlorine test strips are used to measure progress from high to low levels since they are cheaper than lab tests. These strips have also found use in programs where aid workers need a simple field test to confirm drinking water from wells & other sources is safe to drink. Click on the image below to see more information on the 0-10ppm residual chlorine test strip.

Dilution Calculator

Diluting chlorine to the right concentration is not as hard as it looks.  The first thing to know is what ppm or parts per million means. Pure water is 100%  water or one million parts per million. Most alcoholic beverages such as rum, tequila, gin are sold as 40% alcohol or 400,000 parts per million, the rest being water. So, if you had a chlorine bleach solution of 5% or 50000ppm, reducing it to 1% or 10000ppm is straightforward. You simply mix 4 parts of water with 1 part of 5% bleach. This works whether you use cups, buckets or bushels .

PPM: What Is It & Why Is Used?

PPM or parts per million is essentially shorthand for describing small quantities. Most people are familiar with 100%, 10% or 1% but often misread smaller quantities such as 0.1% or 0.01%. If you convert 100%, 10% & 1% to ppm, you get 1,000,000 parts per million, 100,000 parts per million & 10,000 parts per million respectively. At these concentrations, it is inefficient to use ppm, so percentage is preferred. At lower concentrations such as 100 ppm, 10 ppm or 1 ppm, the percent equivalents are 0.01%, 0.001% & 0.0001% respectively. Aside from being inconvenient to use, there is a risk of making a mistake. Miss a zero & the solution you are making is 10 times too strong; add an extra zero & it 10 times too weak.

Click on the Dilution Calculator Video to see it in action:


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Brand Name
Indigo Instruments
Product Name
Very High Level Chlorine Test Strips
USD $21.00
Product Availability
Available in Stock

About Stephan Logan

VP Sales & Marketing at Indigo Instruments. Previously sold hi tech science instruments to researchers. B.Sc. & M.Sc. from McGill University.

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