We clean our carpets at least once a week, twice if heavily soiled and we use scalding hot water and rinse to the point of paranoia. Now about once a month, it's probably a good idea to use some vineagar in a spray bottle and spray it down heavily, let it sit for about 15 minutes, then hang it up and rinse heavily with hot water. We have one of those hand held shower heads which are worth their weight in gold to do this job.
Good luck and I hope this helps
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