The discharge tube of a water heater’s temperature and pressure (T&P) relief valve is designed to safely direct water or steam released by the valve to a designated location. However, having a threaded end on the discharge tube poses a significant safety hazard. Threaded ends allow the possibility of capping the tube, which can block the flow of water or steam during an emergency, potentially leading to dangerous pressure buildup or explosion. This guide explains the risks, code requirements, and steps to fix a threaded discharge tube.

1. Risk of Capping:

• A threaded end makes it easy for someone to mistakenly cap the tube, preventing it from safely releasing pressure or hot water.

2. Pressure Build-Up:

• If the tube is capped or obstructed, excess pressure in the water heater cannot escape, increasing the risk of explosion.

3. Code Non-Compliance:

• Most building and plumbing codes prohibit discharge tubes with threaded ends to ensure unobstructed flow.

4. Increased Liability:

• A threaded discharge tube can lead to accidents, injuries, or property damage, increasing legal or insurance risks.

1. Turn Off the Water Heater:

• For electric water heaters: Turn off the circuit breaker.

• For gas water heaters: Set the thermostat to “OFF” and close the gas supply valve.

2. Inspect the Discharge Tube:

• Check if the end of the discharge tube is threaded.

• If threads are present, proceed to replace the tube with a non-threaded, code-compliant option.

3. Purchase a New Discharge Tube:

• Select a tube made from approved materials, such as:

• Copper

• CPVC

• Galvanized steel

• Ensure the tube diameter matches the relief valve outlet (usually ¾ inch).

4. Remove the Threaded Tube:

• Unscrew the threaded tube from the T&P relief valve using an adjustable wrench.

5. Install a Non-Threaded Discharge Tube:

• Steps:

1. Wrap Teflon tape around the threads of the T&P relief valve to ensure a secure seal.

2. Screw the new discharge tube into the valve and tighten it securely.

3. Ensure the tube slopes downward and terminates no more than 6 inches above the floor or a drain.

• Tips:

• Cut the tube to the proper length if necessary.

• Avoid sharp bends or kinks in the tube.

6. Test the System:

• Open the T&P valve briefly to release water and ensure it flows unobstructed through the new tube.

1. No Threads on Discharge Tube Ends:

• Discharge tubes must not have threads on the outlet end to prevent capping.

2. Unobstructed Flow:

• The tube must allow free flow of water or steam from the relief valve.

3. Material and Sizing:

• The tube must be made of approved materials and have a diameter matching or exceeding the relief valve outlet.

4. Proper Termination:

• The tube must terminate in a safe location, such as above a drain, and not directly on the floor.

1. Inspect Regularly:

• Check the discharge tube for compliance during routine water heater maintenance.

2. Follow Installation Guidelines:

• Ensure the discharge tube adheres to manufacturer specifications and local plumbing codes.

3. Educate Homeowners:

• Inform others about the dangers of capping or modifying the discharge tube.

• If you are unsure about replacing the discharge tube yourself.

• To verify that the water heater and its components comply with local building codes.

• For assistance with installing additional safety features, such as an expansion tank.

• New Discharge Tube: $10–$50, depending on material and length.

• Professional Installation: $100–$300, including labor and materials.

1. Prevents Accidents:

• Ensures the relief valve operates as intended, reducing the risk of explosion or injury.

2. Maintains Compliance:

• Meets building codes and safety standards, avoiding potential fines or complications.

3. Protects Property:

• Directs hot water or steam safely away, minimizing the risk of water damage.

4. Reduces Liability:

• Eliminates the potential for negligence claims due to improper installation.

A threaded discharge tube is a safety hazard that must be replaced promptly with a code-compliant, non-threaded alternative. By ensuring the tube allows free and unobstructed flow, you protect your property, occupants, and water heater system. For assistance, consult a licensed plumber to guarantee proper installation and adherence to building standards.