Many of the humidifiers use a compression fitting over the 1/4-inch line. You can get another ferrule at the plumbing supply. After you turn the water off, cut the tubing off near the old ferrule at the end of the tube, slip the nut back on the line, slip the ferrule on the line, push the line all the way into the compression fitting then tighten the nut over the ferrule and fitting. Turn the water on. If there is a drip, tighten the nut just tight enough to stop the drip.