Direct answer: If water is coming from the pressure relief valve on a Rheem water heater, the usual causes are a pressure relief valve that is not sealing, water temperature running too hot, or house water pressure pushing the tank past its limit. Start by making sure the leak is actually from the valve outlet or threads and not from a fitting above it dripping down.
Most likely: Most of the time, this is either a tired water heater temperature and pressure relief valve or excess pressure in the tank from overheating or high incoming water pressure.
Look at the leak pattern first. A slow drip from the discharge pipe points to the valve opening and releasing pressure. Water around the valve threads can mean the valve body or tank opening is leaking. Reality check: a relief valve that opens once in a while is still telling you something is off. Common wrong move: lifting the test lever repeatedly to 'flush it out' can leave an old valve leaking worse.
Don’t start with: Do not start by cranking the temperature down and ignoring it, or by capping the discharge pipe. A leaking relief valve is a warning device, not a nuisance part.
Water comes out of the pipe attached to the relief valve, usually a drip every few seconds or a small puddle near the floor.
Start here: Start by checking whether the water is excessively hot and whether the leak gets worse during a heating cycle.
The valve dumps water for a short time, often after heavy hot water use or while the burner or elements are running.
Start here: Suspect overheating or pressure spikes before you assume the valve itself is bad.
The body of the relief valve or the threaded connection is wet, but the discharge pipe may stay mostly dry.
Start here: Look for mineral buildup, rust, or a valve that never sealed well in the tank opening.
The valve was dry before, then began dripping after you lifted the lever to test it.
Start here: That usually points to debris on the seat or an old water heater pressure relief valve that will not reseat.
Older valves collect scale on the seat and spring assembly. Once they open, they may keep weeping even when pressure drops back down.
Quick check: Dry the valve and discharge pipe, then watch whether the drip continues after the heater has been idle for a while.
If the tank overheats, the relief valve does exactly what it is supposed to do and dumps water to protect the tank.
Quick check: Run hot water at a nearby faucet and check whether it feels scalding or clearly hotter than normal.
A tank can build pressure as it heats, especially in a closed plumbing system. The relief valve may open even though the heater itself is otherwise fine.
Quick check: Notice whether the leak happens mostly during recovery after showers, laundry, or other heavy hot water use.
Water from a fitting above the valve can track down and make the relief valve look guilty. Heavy rust around the opening can also keep a new valve from sealing.
Quick check: Wipe everything dry above and around the valve, then use a flashlight to see where the first fresh moisture appears.
Water often runs down the tank jacket or piping and makes the relief valve look like the problem when it is not.
Next move: You now know whether you are dealing with a true relief-valve discharge, a threaded valve leak, or a different leak above it. If everything is wet and you still cannot tell where it starts, shut off power for an electric unit or set a gas unit to pilot/vacation and call a pro before water damage spreads.
What to conclude: A discharge-pipe leak usually means pressure or temperature is being relieved. A leak from above the valve points to a different plumbing problem. A leak at the threads can be the valve, the tank opening, or corrosion.
Overheating is one of the most important lookalikes because replacing the valve alone will not solve it.
Next move: If the water is clearly too hot or the leak shows up during heating, the valve may be responding to overheating rather than failing on its own. If hot water temperature feels normal and the leak is still steady, move on to pressure and valve-seat checks.
What to conclude: Very hot water points to a thermostat or control problem on the heater, which is more serious than a simple nuisance drip. Normal temperature makes a worn valve or pressure issue more likely.
A relief valve can be doing its job perfectly if house pressure spikes or heated water has nowhere to expand.
Next move: A leak that mainly shows up during recovery strongly suggests pressure expansion or overheating, not just a bad relief valve. If the valve drips even when the heater is idle and water temperature is normal, a worn water heater pressure relief valve becomes the leading suspect.
If debris is caught on the seat, one controlled test can sometimes stop a fresh drip. Repeated testing on an old valve usually makes things worse.
Next move: If the drip stops completely and stays stopped through the next heating cycle, debris may have cleared from the seat. If the valve keeps dripping after one careful reseat, the practical fix is usually replacing the water heater pressure relief valve after ruling out overheating and obvious pressure problems.
This is where you avoid the two expensive mistakes: replacing a good valve on an overheating tank, or ignoring a bad valve that will never seal again.
A good result: A successful valve replacement leaves the discharge pipe dry during normal operation and through a full recovery cycle.
If not: If a new valve also leaks, the problem is not the valve alone. You are dealing with overheating, pressure expansion, or a compromised tank opening and need a pro diagnosis.
What to conclude: A relief valve is a valid repair when it will not reseat under normal temperature conditions. Repeat leaking with a new valve points upstream to pressure or temperature control.
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Usually because the valve is opening from excess pressure or temperature, or because the water heater pressure relief valve itself is worn and no longer seals tightly. The first job is confirming the water is really coming from that valve and not from a fitting above it.
Sometimes, yes, but only if the heater is not overheating and the leak is truly a valve that will not reseat. If the new valve also leaks, the real problem is usually pressure buildup or overheating.
It can be. The valve is there to release unsafe pressure or temperature. A small drip is not an explosion warning by itself, but it should not be ignored because it may point to overheating, high pressure, or a failing valve.
That is common on older valves. Mineral debris can get on the seat, or the spring and seal may already be worn. One careful test is reasonable. Repeatedly flipping the lever usually makes an old valve leak worse.
No. Never cap, plug, or block a water heater relief valve or its discharge pipe. That valve is a critical safety device and must be able to open freely.
That points more toward pressure rise or overheating than a simple bad valve. If the leak shows up mainly during recovery after showers or laundry, the valve may be responding to what the tank is doing, not failing on its own.