Although some levels of moisture is required to clean and lift stains, it is recommended not to use excess water. Mattresses are very absorbent, which makes it extremely difficult to dry out. This will allow mold and mildew to thrive and fester directly below the area you sleep in. \r \rEven if you're confident you can remove all the water, be aware that some mattress types (such as memory foam) can spoil when in contact with water and disturb the "bounce back" properties it has. So it's always best to remove stains and dirt using a damp cloth while dabbing. Read more