Allow the baking soda to remain on the carpet overnight. You can also use powdered borax in a similar manner. If you use borax, follow any safety precautions on the packaging.
Note that some carpet shampoos are designed to be used in a carpet cleaning machine, while others can be used with a sponge. For instance, you may need to sponge the shampoo into the carpet, allow it to sit for at least 20 minutes, and vacuum the entire area again.
Shake the mixture thoroughly and apply liberally to your carpet. Make more as needed. Note that the room will smell strongly of vinegar until the mixture dries. Once the mixture has dried, vacuum the room completely.
Find 3% hydrogen peroxide at a pharmacy or grocery store. Hydrogen peroxide may lighten the color of darker carpets. As long as you keep the percentage of hydrogen peroxide below 3%, however, this risk is minimal.
Let it sit for a few minutes, blot with a dry towel, and wait 24 hours. If no fading or other discoloration occurs, your mixture is likely safe to use on the rest of the carpet.
A carpet cleaning company may even be able to remove and fully clean a carpet damaged by flooding or another source of persistent moisture.
If cleaning the carpet yourself, mix one part 3% hydrogen peroxide with five parts water and spray the entire carpet on both sides. Then lay it out in the direct sunlight until the carpet is fully dry.
If the source of moisture was temporary or minimal, your may be able to dry out a wet carpet.
