How Much is Enough? How much water is enough? This depends on the style of mattress. Many recommend filling to "1/4" to "1/2" below the top of the frame as an approximation.

Adding or subtracting water can change the feel of the bed a great amount. The number one complaint we have found with mattress comfort is caused by improper mattress filling.

With fiberfilled (or baffled) mattresses rated over 95% waveless, more water makes it appear softer and less water makes it appear firmer.

With a mattress of 90% or less waveless rating, the mattress should be filled to accommodate the largest sleeper for the bed. This is done by filling according to their body. Have them sit in the middle of the bed near the foot with legs dangling over the rail. Rock gently to the left and right. If their bottom only touches when they rock from side to side, it is filled the correct amount.

If their bottom is always touching, add water. If their bottom never touches, drain some. Continue this process until properly filled.