How to Fix a Shower With the Hot and Cold Water Reversed

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It can be frustrating when your shower's hot and cold knobs are reversed. Some people choose to just live with this being the case, but it's a sure sign of a shoddy plumbing job. Either a plumber neglected to test the water when the work was finished or the cartridge is out of alignment. Either way, it's an easy fix, but how you go about it depends on whether you have separate temperature knobs or just one.


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Switching Shower Temperature Knobs

If you have two temperature knobs, you'll need several basic tools to switch the knobs: a flathead screwdriver, a small Allen wrench, a Phillips screwdriver and a wire brush. Get started by turning off your home's main water supply and cover the shower drain with a towel in case anything gets dropped. Designate a clean work area to place all the removed parts so they don't get lost.

Some hot and cold control knobs have covers with the letter "H" or "C." These can be easily removed with a flathead screwdriver, and it may be possible to simply switch them. If not, look underneath and on the backs of the covers for retaining screws. Unscrew these and remove the controls from the shower wall.


Cleaning and Completing the Project

You'll now see the shower lines protruding from the wall, and you can clean these with a wire brush to help remove water deposits. Dry the lines off to get rid of any mineral dust that might have accumulated from the brushing.

Now you can put the controls back onto the lines in the opposite positions that they were in previously. Be sure that they're carefully placed all the way back onto the shower lines. Tighten new retaining screws onto each of the controls. Test the knobs and ensure they were installed correctly.


Single-Knob Temperature Control Repair

If you just have one knob with the temperature reversed, you'll need to proceed differently. After turning off the water supply and covering the drain, look for the center screw on your hot and cold shower faucet knob. If there's a cap on top of the handle, pry that off before unscrewing and removing the screw. To remove the knob, lift it up, tilt it back and slide it off the shower wall.

If there's a second knob, handle or escutcheon plate behind the first knob, you may need to remove it as well. Some models also have retaining rings and clips, which can be slid off. Now you should be able to see the shower cartridge, which could be the root of the problem.


Repairing Shower Cartridges

At this point, you're ready to pull out the cartridge. If there's a clip holding it, use needle-nose pliers to remove it. Firmly grasp its top point with a cartridge removal tool and pull it straight out. Turn it around about halfway from its original position and slide it back in until it fits tightly. Put back the retaining ring, clip, handle and cap.

If this doesn't reverse the hot and cold water positions, you may need to buy a new shower cartridge. The retaining ring and clip, shower knob, cap and screw may also need to be replaced. If this is the case, take all the parts needing replacement to the hardware store to make sure that you purchase the correct ones.