Question:
Design an experiment to test drinking water filter cartridge?

I would like to perform a test to see if my Brita Filter cartridge is still effective. What would be your suggestion in designing an experiment to test the water filtered by these cartridge?

I have access to use microscope, petri dishes, incubator, x-ray diffraction machine, gas chromatography, pH meter, and regular chemical experiment equipments.

Answer: You need to test the water before and after filtration. This will let you determine what, if anything, the filter removed (or added) to (from) the water.

The microscope can be used to detect particulates. The petri dishes, and incubator can be used for microbial (bacteria and fungi) growth, but the shouldn't be any microbes in your drinking water before you filter it. The govenment has a TMDL of 0 for all microbes.

I'm not sure how X-ray difraction works and I believe gas chromatography take a small amount of a solid material and vaporizes it, so I don't think it would work.

You can test pH before and after, but that won't give you very much information.