RO Membrane: Replacement Time… Or Not Yet?

Reverse osmosis (RO) membranes are often touted as one of the most effective water filtration systems out on the market today. In fact, you or some of your friends may have have water filtration systems at home that come with RO membranes. However, these efficient membranes also have shelf lives like every other machine and must be replaced at some point in the future. You can even do the replacement check yourself.

Start by acquiring two clear plastic bottles and a conductivity meter. The latter is needed to measure the density of negative ions in the water sample. Place a bottle under the tap of a sink connected to the RO membrane system. Fill up the bottle with water while keeping it on for roughly 30 seconds. Next, find a faucet with no RO filtration system and fill up the other bottle with water.

Bring out the conductivity meter and dip the meter’s probe into the water bottle from the first tap—the readings should register the ion count. Jot down the results from the first bottle. Proceed with logging the data from the second bottle. The object is to determine the level of ion saturation in both bottles. Some sources say that a large difference between the compiled data or readings from both water bottles indicate no need for replacement. The values being not so far off could mean that the RO filter is already saturated or ineffective.