Manufacturers recommend yearly cleaning and also apply carpet protectant for a healthier environment and also prolonging carpet replacement, up to 5 years. Also on top of all of this you should be vacuuming at least once a weak. To make sure your carpets last to their full potential I would also recommend having a heavy bristled carpet right by your door to wipe your shoes with or just make everyone take their shoes off. This will help with keeping wear at a minimum, as well as soiling.
