When the hot and cold water are reversed on a faucet, it can cause confusion, inconvenience, and even safety concerns, particularly for young children or the elderly. The problem typically stems from improper installation or incorrect connection of supply lines. Fixing this issue ensures proper functionality and user safety.

1. Incorrect Supply Line Connection:

• The hot and cold water supply lines were swapped during installation.

2. Misaligned Cartridge:

• In cartridge faucets, an improperly installed or rotated cartridge can reverse water flow.

3. Faulty or Incorrect Valve Installation:

• Mixing valves or diverters were installed incorrectly.

4. Manufacturing Defects:

• Rarely, a faucet may have been assembled incorrectly at the factory.

1. Identify the Faucet Type:

• Determine whether the faucet is a compression, cartridge, ball, or ceramic disk type. Single-handle faucets often have cartridges, while double-handle faucets use separate valves for hot and cold.

2. Turn Off the Water Supply:

• Shut off the hot and cold water supply valves under the sink.

• Open the faucet to release any residual water.

3. Inspect the Supply Line Connections:

• Locate the hot and cold supply lines under the sink.

• Hot Water: Typically connected to the left-hand valve or side.

• Cold Water: Typically connected to the right-hand valve or side.

• If the lines are crossed, use an adjustable wrench to disconnect and swap them.

4. Check the Cartridge (For Single-Handle Faucets):

• Remove the faucet handle using a screwdriver or Allen wrench.

• Pull out the cartridge and inspect its orientation:

• The hot water inlet should align with the left side, and the cold water inlet with the right.

• Rotate the cartridge 180° if needed to correct the alignment.

• Reinsert the cartridge and reassemble the faucet.

5. Inspect Mixing Valves or Diverters (For Complex Systems):

• If the issue persists in systems with mixing valves (e.g., showers), check the valve’s orientation.

• Reinstall the valve according to the manufacturer’s instructions to ensure proper alignment of hot and cold inlets.

6. Test the Faucet:

• Turn the water supply back on and check the faucet.

• Confirm that the hot water flows from the left side or when the handle is turned to the left, and cold water flows from the right or when the handle is turned to the right.

1. Verify Connections During Installation:

• Double-check supply line connections and cartridge orientation when installing a new faucet.

2. Follow Manufacturer Instructions:

• Ensure all components are installed according to the provided guidelines.

3. Hire Professionals:

• Use a licensed plumber for new installations or complex plumbing systems.

• If the issue persists after reconnecting supply lines or adjusting the cartridge.

• For faucets connected to complex plumbing systems or inaccessible areas.

• To diagnose and resolve problems in showers or bathtubs with integrated mixing valves.

• DIY Repairs:

• $0–$20 for basic tools or replacement cartridges (if needed).

• Professional Repairs:

• $75–$200 for labor, depending on the complexity.

• Valve Replacement or System Repairs:

• $200–$500+ for extensive modifications.

1. Improves Usability:

• Ensures intuitive operation, especially for guests or children.

2. Enhances Safety:

• Prevents accidental exposure to hot water, reducing the risk of burns.

3. Complies with Standards:

• Most building codes require proper hot and cold water orientation for user safety.

4. Reduces Frustration:

• Restores convenience and functionality to the fixture.

Fixing reversed hot and cold faucets is usually a straightforward task that involves correcting supply line connections or realigning the faucet cartridge. With basic tools and attention to detail, many homeowners can resolve the issue themselves. For more complex systems or persistent problems, consult a licensed plumber to ensure professional results.