You will be able to tell by the taste and clarity of the water. For example, ice cubes made with the R.O. water are harder, clearer, and last much longer. If you take two clean glasses of the same size and put ice cubes made with R.O. water in one and the same number of ice cubes made from tap water in the other, you will notice that it takes longer for the R.O. ice cubes to melt. Not only do ice cubes made with R.O. water last longer but juices and mixed drinks made with R.O. water taste better. When ice cubes made from tap water are melted in a glass, you will most likely see unsightly sediments on the bottom. This is not so with R.O. water. Another way of determining the amount of dissolved solids removed from tap water is by the use of a conductivity meter. This meter measures the conductivity the dissolved solids impart to the water. This is converted on the meter scale into parts per million of Total Dissolved Solids (TDS). Premier offers a water sample kit for the testing of a customer’s water to determine how the TFM membrane is working and when to replace the membrane.