Free Chlorine Test Strips, Residual Low Level 0-10 ppm, 50-Pack

I don’t have a way to calibrate against these strips but based on the amount of bleach we pump into the well water it looks reasonable. Very easy to get the reading (1 or 2 ppm chlorine). Also bought a local hardware store strips and even though the chlorine is definitely in the water the local strips keep reading 0 ppm.

The strips have not detected any Chlorine in the city water (which, according to the city, is present there) so I ran the following test: Used bleach purchased at a local store that according to the label yields 7.13% available chloride. Mixed 2400ml of well water (the test was done at a rural house that does not have municipal water supply) and 100ml of bleach. This should have created a solution with 2852 ppm of chlorine in it, if I am not mistaken (7.13%*(100/2500)*1000000) Then I started the process of diluting the solution in half and using the strips at every step to test the concentration. The results are shown in the picture. The strips can reasonably well detect the concentration of about 20 ppm of chlorine or higher, but will not work for any lower concentrations. This make them useless for the purpose that I intended them to use.

Works fine

Checked Against a chlorinator real close to the PPM readings

Found water leaking onto our property. Municipal workers told me it was a natural spring, but this was in the middle of a very dry spell. Got this kit and detected trace amounts if chlorine matching those in municipal water mains. Definitely not a natural spring!! Eventually traced it back to a neighbors broken water service but 100% helpful in determining the real source.

Unfortunately these proved completely useless for my use case and a waste of money. I was hoping to use these strips to diagnose the origin of water leaking into our basement, but as mentioned in other reviews these strips just can’t detect the levels of chlorine in city water. I confirmed our city’s water is chlorinated with free chlorine (and not chloramine), which is noticeable through a strong smell of chlorine when the water comes out of our taps. However tests of water direct from tap compared to distilled, boiled, filtered and the water coming into our basement yielded no noticeable difference in results, as shown in the photo. I can’t vouch for how these perform for higher concentrations of chlorine, but for levels in drinking supply they are basically useless.