These water test tablets will give you a reading as low as 50PPM of hardness, so in most circumstances, they are perfect for determining which taps in your home are on soft or hard water or for just knowing if your water softener is producing softened water.
According to the official gauge of water hardness, anything below 70PPM is considered soft water. However, it is worth noting that the higher hardness levels, from about 30PPM upwards, can leave cosmetic watermarks. If you need more accurate testing, you’ll need Kit 2: Accuracy Test Kit.
Fill the plastic tube with the water you want to test up to the 10ml line, add a tablet and cover the tube with a finger, or put the lid on and give it a good shake. If the water goes green, then the water is 50PPM or less. If the water goes orange, then the water is hard.