You need to test the residual level of Hydrogen Peroxide in your water tanks to confirm that enough peroxide remains to kill bacteria and viruses. The test strips are really very simple to use, every Sunday morning before my wife even gets out of bed I have watered the vegetable garden and bade coffee. As the water at the kitchen tap is now fresh, I fill a glass, dip the test strip in for a few seconds and then, compare the colour of the indicator bar on the strip to the colour chart on the bottle. If the level of Hydrogen Peroxide is 2.0 ppm (parts per million) as indicated, I know that everything is safe. If however the level is below 2.0 ppm, I know that my very next job is to add some Hydrosil to the tanks.
Testing of the peroxide level in the tanks should be carried out every Sunday morning to make sure that you have sufficient residual peroxide in the water and that your water is safe to drink. The other indicators that you need to do a water test is of course if and when it rains!