Carpet is a wonderful addition to any home. The padding underneath makes carpet extremely soft to walk on. The problem is when you spill on your carpet, the liquid seeps through into the carpet backing. The carpet and backing can take days to dry. Excessive water in your carpet backing can promote the growth of mold, mildew, and bacteria. In fact, if you do not dry your carpet within 24-48 hours of a water spill, bacteria will grow.
The obvious answer is to first check for visible signs of mold in your carpet. Next, simply smell your carpet where you remember there was a spill. If it smells like mold or mildew, then you probably know it is in your backing or padding.