Thank you for your question, and I am sorry to hear that you are experiencing a leak from your Delta faucet. There is a bonnet nut that is holding the cartridge down, underneath your handle. We recommend to tighten the bonnet nut to stop the leak. To do this, turn the water off at your shut off valve. Remove the handle. Tighten the bonnet by turning clockwise, to the right. Install the handle back on and turn the water back on. Test the faucet. If the faucet still leaks, we recommend to replace both the valve cartridge assembly, RP50587, and the bonnet nut, RP51503.
Date published: 2018-04-10