John asks:

I have a water softener and a pre-filter ahead of my Reverse Osmosis System. How often should I change the filters?

The Water Doctor replied: Water quality varies so much that it is impossible to give you an accurate answer. For example, some water is more turbid and contains more solids. Water that looks substantially the same could plug a filter in a month... or a year. The thing is, you don't want to wait until the filter is plugged, you want to changed it before solids or chlorine comes through. On hard water, I have seen membranes last six months to a year and on soft water, they can easily last three to five years.

In my own personal case, I have one of THESE in my home. I test the water hardness and chlorine levels on a weekly basis and these the RO for TDS levels multiple times a week. The only way you can know if your membrane needs changed is by testing the TDS and when it drops to below 80% rejection, it is time to change it. By testing the softness of the water, you can know how well it is working and adjust it to meet your needs. In many cases you can change the RO Filters on a yearly basis, if you have soft water and proper pre-filtration, but it never hurts to do it more often. After all, this is your drinking water we are talking about.

For whole-house filtration, the absolute best filtration is a 5 micron "Pleated" filter like THIS. At the very minimum, if you have a water softener, you should at least have a test kit to test the hardness, like this: Hardness Iron & PH Field Analysis Water Test Kit It is good for 50 tests, so if you test your water once a week, it will last a year and then the testing chemicals can be replenished HERE. The professional grade test kit includes tests for pH, iron, chlorine and TDS, but you can also buy a TDS meter HERE. Everyone that has a reverse osmosis system should have a TDS meter and this is a professional-grade model that lasts for years. You wouldn't dream of having a furnace or air conditioner without a thermostat - why on earth would you have a reverse osmosis system without a TDS meter? Think about that! Here is the LINK to all of our water testing products.