The cold water handle assembly of my Kohler Stillness wall mount faucet keeps unscrewing from the valve body after a few days of use. I've hand-tightened it as the instructions say to but is there something else I can do to keep it secured to the valve?

Remove sprayer and hose from faucet body.
Remove handle and cartridge.
Pull up on body.
Replace parts and reinstall in reverse order.

Download the instructions from Kohler.

Generally the sprayer trigger assembly will unscrew from the hose. You can then point the hose toward the sink and turn on the
water. It should flow freely through the hose when either the hot or cold is on. Generally there is a aerator on the spray head. You can access it by unscrewing the tip of the sprayer assembly and clean out any mineral deposits. There may also be an inline type filter in the handle where it screws onto the hose that can be removed and cleaned. If this doesn't help I would guess the on-off triggering assembly is broken and you would have to replace the sprayer head.Hope this helps.

The handle has a allen set screw loosen that until the handle comes off then the bonnet nut will unscrew revealing the bonnet cap and washer the cartridge should be under that most kohler's require a special tool to remove cartridge(turn water to faucet off prior to working on faucet,also note how everything is removed it needs to be replaced in same order especially the cartridge,also you should use plumbers grease to coat all seal when replacing everything).

leaking around handle?Turn water off under sink.remove handle,cover plate,unscrew valve stem assembly,and turn the two pieces apart to expose o ring,and replace

yes, and hopefully piece's of the cartridge's rubber have not come off and lodged in the water port's.have had this problem quite a few time's.remove your cart' and while it's out, run water to flush out the valve body.shine some light in body before re-assembly.

I dont know the modle fauset you have ,but it sounds like your cartridge has turned in the valve body. It should lock into place in the valve body with a tang in the cartridge and a slot or groove in the fauset body. If the whole cartridge assembly turns in the fauset it will couse this problem.

Verify the cold water outlet has equal pressure as the hot side outlet at the wall. Check the inlet screen on the cold side water line where it attatches to cold water pipe. The screen could be plugged. Then check the cold side hose for any restrictions. Also check if there is a screen on the outlet side of the cold water hose and see if it is plugged. Otherwise the faucet valve is mis-aligned and will need to be rotated and re-tightened to align the valve to the center so both sides have equal water flow.

tun off the water.
unscrew teh allen screw under neath the handle. pull out hteh handle. undo the wall plate and gain access to the cartridge in the handle body. turn the artridge around 180 degree and reisntall all parts.

you will have to replace the ball assembly with a repair kit
1 turn the water off under the sink (hot and cold)

remove the handle ( you may need an allen head wrench to remove a hex screw or you may have to take a channel lock pliar and unscrew achrome
nut over the ball mechanism

after the handle comes off there is usually some type of lock nut that you must remove to remove the ball mechanism

remove the ball (usually chrome or brass(ther are usually little springs and rubber washers under ball

take ball and washer to ACe or lowes and match the pieces (usually sold as a kit

follow directions and installl

turn water on and pat yo!ur self on the back !