A distributor came to our office and bought 100 pcs. slim 20 sediment filter with 5 micron rating.

He told me that the 5 micron rating is very effective in filtering suspended solids from the water not unlike the 10, 20 and 30 micron ratings.

As per his concept, there is a very big difference in filtration efficiency if you will be using the 5 micron filters.

If you try to see the diameter of a hair strand, it is rated 75 micron, the smallest visible particle that can be seen by the naked eye is 40 micron and below 40 micron you need to use a microscope.

So,5,10,20,30 and even 1 and .5 micron are all within the micro filtration range based on the filtration spectrum and since we just monitor the clarity of water using our naked eye, we cannot see the difference in terms of filtration efficiency not unless we use the turbidity test comparison and the silk density index test (SDI).

In water refilling station operation, the DOH monitors the turbidity of water to the maximum of 5 NTU (nephelometric turbidity unit) and above the said range, it is no longer considered drinking standard.

MWSS water as per turbidity test (without undergoing any filtration) has a turbidity of 1 NTU and after being processed as RO water will have a turbidity of .o something and the mineral water will be having 0.something.

Since the DOH has a maximum range of 5 NTU, why is it that we are trying to choke ourselves with our own prescribed standard by using 5 micron filters and even 1 and .5 microns? in fact the lower the micron rating the higher the pressure drop, and to think that these sediment filters will not remove foul taste and even will not enhance the taste of the water being filtered, there is no need to exaggerate its use.

Hope that I was able to share my thoughts to all of you.