Vacuum your carpet weekly if the dining room is used daily. With small children or pets in the home carpets may need to be vacuumed twice a week. Formal dining rooms only need attention every other week and after they have been used.
Clean carpets using 1/3 cup food grade distilled white vinegar per gallon of boiling water. Carpet shampoo leaves a sticky residue that attracts dirt causing the carpet to soil in short order. Vinegar removes the residue so carpets stay cleaner far longer. Then rinse with hot water.
Vinegar also reactivates the shampoo already in the carpet and extracts the residue out of the carpet along with the dirt. Your carpets will feel soft and stay clean much longer.