Open Question: MSR sweet water cartridge - how long does it stay good for?

I bought a new cartridge for my sweet water pump about 4 years ago. I've been very busy the past few years, and so I've only used it for about 10 days. I know the cartridge needs to be replaced after pumping a certain amount of water, but will it go badly merely because of passage of time as well?

Source:
http://answers.yahoo.com/question/index?qid=20110817152929AAFv2kp

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