How often to change filters in reverse osmosis system

If you have a reverse osmosis system for a while, you’ll eventually begin to wonder when you should change the filter so that the water will always come out clean. This might be a little tricky as many people suggest many different timespan. In this article, we will give you some basic guidelines to give you a general idea of when is the perfect time to replace the filter.

Reverse osmosis water system

Follow the instructions

The simplest course of action to take is to do exactly as it is printed on the instruction. If the manufacture suggests that you replace the filter after 12 months, then somewhere in the time range is OK. The number usually indicated standard, common usage frequency. If you use it a bit more, then replace it earlier. If not, a bit later is still OK.

How many stages?

If yours is a 3-stage system then you will need to replace it sooner than a 5-


stage one. 5-stage reverse osmosis filter can produce cleaner water for a much longer time than its 3-stage cousin. Therefore, it makes sense that you replace the filter later than. My recommendation is to replace the filter after 1,5 years for the 5-stage one and 1 year for the 3-stage one.

You can test the water as well. If the number is 100 particles per million for the 3-stage unit, then it is time to replace it. If it is 200 particles per million for the 5-stage unit, it is time to get a new filter.

Test the water

If you are unsure about the amount of usage because you use your machine so inconsistently, then your best bet is to test the water. Use a water indicator to do a sample test. The appropriate at most popular bottling companies is around 50 to 200 particles per million. If your water exceeds this number, a replacement is definitely needed.

However, if you only want the best water for you and your family, you can replace it a little bit earlier than recommended. Or if your immune system is too strong and you are short on cash, replacing it a little bit later is OK as well. Just make sure that it is not too late or you will end up in the hospital.



To sum it all up, it all depends on what type of unit you have, what is the timespan that the manufacture recommended and what your frequency of usage. Take all of those into account and add or minus a few months from the recommended replacement date and you will know when it is time to get a new filter.

Mine at home is a 5-stage filter which has been used for about 1 year. My usage is somewhat consistent and the instructions tell me to replace the filter after 12 to 24 months. Doing the math, I would probably replace my filter after around 1,5 years.

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