Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
This page shows how to find the discharge line that runs from the temperature and pressure relief valve (the T&P valve, or the TPR valve) on a storage-type water heater, and how to look at it for four faults that show up in a lot of homes: a capped or blocked end, a pipe that turns upward instead of running down, an open end that finishes high up instead of low, and threads on the outlet. It needs no tools beyond a flashlight and takes a few minutes. Nothing on this page is touched, moved, or adjusted; you are only looking.
What this page will not do is have you lift the test lever on the relief valve. A valve that does not close again after a test releases scalding water into the room, and once that starts there is no way for you to stop it. This page also will not print the exact height, pipe material, or pipe diameter your discharge line should have, because Rheem's own installation instructions and general plumbing practice both treat those figures as specific to the water heater and to your local code, not as one number for every home. If you find a fault, this page tells you to bring it to a qualified plumber rather than fix it yourself.
Safety
DO NOT LIFT THE TEST LEVER ON THE RELIEF VALVE.
A valve that does not close again can send hot water into the room.
Necessary equipment
| Item | Note |
|---|---|
| Flashlight | The space around a water heater is often dark. |
| Pen and paper | Use these to record each fault that you find. |
| Manual for your water heater | The manual gives the correct height, material and diameter for your discharge line. |
Before you start
Estimated 2 min to 6 min
- Find the manual for your water heater.2mReport a problem with step 1, Before you start
- The manual gives the correct height, material and diameter for your discharge line.
- Many manufacturers give the manual on their website at no cost.
- Find a flashlight for this inspection.<1mReport a problem with step 2, Before you start
- The space around a water heater is often dark.
Find the relief valve and the line
Estimated 2 min to 4 min
- Find the relief valve on your water heater.1mReport a problem with step 1, Find the relief valve and the line
- The valve is usually near the top of the tank, on the side or on the top.
- The valve has a lever or a handle on the top.
- Find the pipe that connects to the relief valve.<1mReport a problem with step 2, Find the relief valve and the line
- This pipe is the discharge line.
- Some manufacturers call this pipe the T&P pipe or the TPR pipe.
- Follow the discharge line from the valve to its open end.1mReport a problem with step 3, Find the relief valve and the line
- The open end can be near the floor, outdoors, or above a floor drain.
- A line that runs inside a wall or under a floor needs a plumber to trace it.
Look at the line for four faults
Estimated 3 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
KEEP YOUR HANDS AND YOUR FACE AWAY FROM THE OPEN END.
The valve can open at any time and hot water can flow from it.
- Look at the open end of the discharge line.<1mReport a problem with step 1, Look at the line for four faults
- A pipe cap can block this end.
- The end must stay open at all times.
- Rheem states that you must not block the outlet of the relief valve.
- Look for an upward turn anywhere in the discharge line.<1mReport a problem with step 2, Look at the line for four faults
- Rheem states that the line must run downward from the valve to its open end.
- Water stays inside the line at an upward turn.
- Water inside the line can freeze in cold weather.
- Look at the height of the open end above the floor or the drain.<1mReport a problem with step 3, Look at the line for four faults
- A high open end can send hot water at your face.
- Your manual and your local plumbing code state the correct height for your water heater.
- Do not change the height of the open end.
- Look for threads at the open end of the discharge line.<1mReport a problem with step 4, Look at the line for four faults
- An open end with threads lets a person attach a cap or a hose.
- A cap or a hose can block a discharge completely.
- Rheem states that the open end must not have threads.
After the inspection
Estimated 4 min to 8 min
- Write down each fault that you found.1mReport a problem with step 1, After the inspection
- Use the four checks in this section as your list.
- Note the model number and the serial number of your water heater also.
- Compare your notes with the manual for your water heater.2mReport a problem with step 2, After the inspection
- The manual gives the height, material and diameter for your unit.
- Your local plumbing code can add further rules for your area.
- Speak to a qualified plumber if you found one fault or more.<1mReport a problem with step 3, After the inspection
- Do not correct a fault yourself.
- Do not clear a blocked open end yourself.
- Give the plumber your notes and the model number of your water heater.1mReport a problem with step 4, After the inspection
- Your notes save the plumber a second visit to look at the same fault.
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- relief valve discharge pipe
- Also called: overflow pipe, drip pipe, relief valve pipe, pressure relief pipe, T&P discharge pipe, water heater drain pipe
- temperature and pressure relief valve
- Also called: T&P valve, TPR valve, pressure relief valve, temperature pressure relief valve, pop-off valve, t and p valve
- water heater
- Also called: hot water heater, hot water tank, hot water cylinder, boiler, geyser
When to use a professional
Speak to a qualified plumber if you find any of the four faults on this page. Do not remove a cap from the open end yourself. Do not bend or replace the discharge line yourself. Do not change the height of the open end yourself.
A qualified plumber must select the pipe material and the pipe diameter for your discharge line. Local plumbing code governs these choices. The code differs between areas. Give the plumber your notes and the model number of your water heater.
This page does not cover a test of the relief valve. A qualified plumber can test the valve safely. A qualified plumber can replace the valve if a test fails. Speak to a qualified plumber also if the valve opens on its own without a test.
Speak to a qualified plumber if the valve releases water on a regular basis. Rheem states that a closed water system can cause this discharge. Do not block the outlet of the valve to stop the discharge.
Common questions
What is the T&P valve or the TPR valve on my water heater?
T&P stands for temperature and pressure, and TPR stands for temperature and pressure relief. Both names refer to the same safety device: a valve, usually near the top of a storage water heater, that opens automatically if the water inside gets too hot or the pressure inside gets too high. A pipe runs from this valve to a safe place to release water, and that pipe is what this page inspects. The valve itself is not covered here, only whether its discharge pipe is installed the way manufacturer instructions describe.
Why is water dripping from the pipe on the side of my water heater?
A little water from this pipe is not automatically an emergency, but it always means the relief valve has opened at least once. The most common cause is thermal expansion: heating water in a closed plumbing system raises pressure until the valve releases some of it. Mineral buildup or a worn valve seat can also cause a slow, repeated drip. This page will not tell you to replace or adjust the valve yourself. Call a qualified plumber, and mention whether the drip is constant, occasional, or only after hot water use.
Is it normal for the end of this pipe to be capped or connected to a hose?
No. Rheem's own installation instructions, reviewed for this page across three of its use and care manuals, say the discharge line must end in open air, with no cap, plug, or hose fitting on its outlet. A capped or connected end can turn a safety device into a source of trapped water, because the water the valve is designed to release has nowhere to go. If you find a cap, a plug, or a hose on this pipe, do not simply remove it yourself. Call a qualified plumber, because removing it does not explain why someone added it.
Can I test the relief valve myself by lifting the lever?
This page deliberately does not walk you through that test. Some water heater manuals do describe an annual test where the owner lifts the lever briefly to confirm the valve opens and closes again, but a valve that fails to reseat afterward discharges scalding water into the room with no way for you to stop it. That is a documented outcome, not a remote one; Rheem's own manuals carry a DANGER notice about it. This is why this page limits itself to a visual check of the pipe. If you want the valve tested, ask a qualified plumber to do it.
What is wrong with a discharge pipe that turns upward or runs uphill at any point?
The pipe is supposed to drain completely by gravity after the valve closes, and an upward turn stops that from happening. Water left standing in the pipe can freeze in an unheated space and block the line, which defeats the purpose of the valve on the next hot water event. It is one of the four faults this page teaches you to look for, alongside a capped end, a high termination point, and threads on the outlet. A plumber can usually correct it by rerouting the pipe rather than replacing anything.
Who fixes a water heater discharge pipe that fails one of these checks?
A qualified plumber, not a homeowner working from a webpage, including this one. The correct height above the floor, the approved pipe material, and the minimum pipe diameter are set partly by the manufacturer of your specific water heater and partly by your local plumbing code, not by one number that applies everywhere. Bring the plumber your written notes from this inspection and the model number from your water heater's rating plate. Give the plumber the manual for your unit if you have it.
Related procedures
- How to find and record the model and serial number of every appliance in the house
- Where is the water under my hot water heater coming from, and does it mean I need a new one?
- How to flush a water heater
- How do I insulate the hot water pipes at my water heater
- How hot should my hot water be and how do I check it
- How do I read the label on my hot water heater and figure out what the numbers mean
- How to test a sump pump and its float switch before the wet season
- How old is my water heater and how do I read the serial number
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
- Tier 1Electric Residential Hybrid Water Heater Use & Care Manual (AP23657 Rev 04)
- Tier 1Power Vent Gas Water Heater Use & Care Manual with Installation Instructions (AP17506)
- Tier 1Fury Direct Vent Residential Gas Water Heater Use & Care Manual with Installation Instructions
- Tier 1Avoiding Tap Water Scalds (CPSC Publication 5098)
Revision history
Current version 1 · updated 2026-08-03 · next review due 2027-08-03
- v1 · 2026-08-03First draft. Visual inspection of the T&P/TPR relief valve discharge line for four faults common across installations: a capped or blocked end, an upward turn that traps water, a high termination point, and threads on the outlet. Grounded in three already-registered Rheem use and care manuals (electric heat pump, power vent gas, and Fury direct vent gas) that agree word-for-word on the discharge-line design rules. Testing or operating the relief valve is out of scope by design, per the backlog note: a valve that fails to reseat discharges scalding water with no way for the reader to stop it. Termination height, pipe material and pipe diameter publish as consult-the-manual-and-local-code because Rheem's own instructions and general plumbing practice treat these as per-unit and local-code matters, not a class-wide number. No new source was needed beyond the three Rheem manuals and the existing CPSC scald publication, all already in the registry.
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.