Short answer: A water heater usually leaks for one of seven reasons: loose supply connections, a failing temperature and pressure relief valve, a worn drain valve, condensation, a leaking anode port, high water pressure, or a tank that has rusted through. The first six are often fixable. A leak from the tank body means replacement.
Finding water around your water heater is stressful. The good news is that not every leak means you need a new heater. In this guide we walk through the seven most common causes, how to tell them apart and what each one means for your wallet. If water is actively spreading right now, skip ahead to the safety steps, then call our leaking water heater repair team in Newark.
First: is it safe to look?
Before you start investigating, do three things:
- Shut off the cold water supply. It is the valve on the pipe going into the top of the heater.
- Turn off the energy. Flip the breaker for an electric heater. Turn the gas knob to "Off" or "Pilot" on a gas heater.
- Stay clear of the relief valve if hot water or steam is spraying from it.
If you smell gas, leave the house and call your gas utility or 911 from outside.
How do I find where the leak is coming from?
Water runs downhill, so the puddle is rarely right under the leak. Dry everything with a towel, then watch and feel these spots from the top down:
- The cold and hot pipe connections on top of the tank
- The relief valve on the top or side, and the pipe that runs from it down toward the floor
- The anode rod port (a hex head on top of the tank)
- The drain valve near the bottom
- The burner area behind the access cover on gas heaters
- The seams and base of the tank itself
A dry paper towel pressed against each spot makes even a slow drip easy to see.
Why is my water heater leaking? 7 common causes
1. Loose or corroded supply connections
What you see: Water on top of the tank, dripping down the sides.
The cold inlet and hot outlet connections can loosen over time from heating and cooling cycles. Older homes may have steel nipples or flexible connectors that corrode. This is often a simple fix: tighten or replace the connector.
2. A failing temperature and pressure (T&P) relief valve
What you see: Water coming out of the pipe attached to the valve, or dripping from the valve body.
The T&P valve is a safety device. It opens if tank pressure or temperature gets too high. If it drips now and then, the cause is often thermal expansion. If it leaks all the time, the valve may be worn out. Never cap or plug this pipe. It must be able to release pressure.
3. A worn drain valve
What you see: Drips from the spigot near the bottom of the tank.
Many tanks come with a plastic drain valve. Sediment can keep it from sealing after a flush, or the washer wears out. A brass replacement valve usually solves it.
4. Condensation (gas heaters)
What you see: Water drips onto the burner or collects under the heater, mostly when the tank is filling with cold water.
When very cold water fills a gas heater, moisture from burning gas can condense on the cold tank and drip down. This is more common in winter, when Delaware's incoming water is at its coldest. It should stop once the tank heats up. If it doesn't stop, the "condensation" may really be a tank leak.
Not sure what you are looking at?
Send us a photo when we call, or have us come take a look, 24/7.
5. A leak at the anode rod port
What you see: Water or rust around the large hex head on top of the tank.
The anode rod screws into the top of the tank. Its threads can corrode and seep. Sometimes resealing or replacing the rod fixes it. If the tank's threads are badly rusted, the tank may be near the end.
6. High water pressure or thermal expansion
What you see: The relief valve drips, pipes bang, or connections leak again after you fix them.
If your home has a check valve or pressure regulator at the meter, water that expands as it heats has nowhere to go. Pressure spikes every time the heater runs. Adding an expansion tank and checking the pressure regulator usually fixes it. You can test pressure with a cheap gauge on an outdoor spigot. Readings over about 80 psi are a red flag.
7. The tank has rusted through
What you see: Water coming from the tank body, bottom seam or under the jacket, often with rust stains.
Inside every steel tank is a glass lining and an anode rod that protect it from rust. Once the anode is used up and the lining cracks, the steel corrodes from the inside. There is no safe patch for a tank leak. The only fix is water heater replacement.
Quick guide: leak location vs. likely cause
| Where the water is | Most likely cause | Repairable? |
|---|---|---|
| Top of tank, at pipes | Loose or corroded connectors | Usually yes |
| Pipe running down the side | T&P valve opening or failing | Usually yes |
| Drain valve | Worn valve or washer | Yes |
| Under a gas burner (only when cold) | Condensation | Often normal |
| Top hex head | Anode rod port | Sometimes |
| Tank body or base | Corroded tank | No, replace |
Why leaks are common in older Newark homes
Many neighborhoods around Newark were built in the 1970s and 1980s. Plenty of these homes still have water heaters that are 12 years old or older, and some have older connectors and no expansion tank. That combination makes leaks more likely. Newark's city water is only slightly hard, which helps, but sediment still builds up over the years if the tank is never flushed.
How to prevent water heater leaks
- Flush the tank once a year so sediment does not keep the drain valve from sealing. Our flushing guide shows how.
- Check the anode rod every 2 to 3 years. A spent rod lets the tank rust from inside; see our anode rod guide.
- Fit an expansion tank wherever a pressure regulator or meter check valve traps expanding water.
- Keep the temperature near 120°F. The U.S. Consumer Product Safety Commission recommends it to prevent scalds, and lower heat is gentler on the tank.
- Put a pan and leak alarm under tanks in closets or above finished rooms.
Local note: Leaks in Pike Creek condos can reach the unit below, and Bear townhome closets hide drips behind a door. In older Wilmington basements, tanks often sit beside a floor drain, so a relief valve leak can run for weeks before anyone notices. If the leak caused damage, our guide to homeowners insurance and water heater leaks explains what to document.
Related reading: Learn whether a leaking water heater is dangerous, and see why a water bill jumps when a valve leaks into a drain.
When should you call a water heater professional?
Call a pro if:
- You can't find the source after drying everything
- The leak comes from the T&P valve or its pipe
- Water is coming from the tank body or base
- The heater is gas and water is near the burner
- The heater is more than 10 years old
- You have tightened a fitting and it still leaks
A pro can test pressure, check the anode and tell you honestly whether a repair is worth it. In Delaware, that work falls under a state plumbing license.
Water heater leaking in Newark? Call (302) 732-0874 for leaking water heater repair from Newark Heater Pros.
Frequently asked questions
Why is my water heater leaking from the bottom?
A bottom leak can come from the drain valve, from the relief valve pipe that runs down the side, from condensation on gas units, or from the tank itself. If the drain valve and relief pipe are dry and the tank base is wet, the tank has likely failed.
Can I still use my water heater if it is leaking?
It is best not to. Shut off the cold water supply and the gas or power until you know the source. A small drip can grow fast, especially if the tank is corroding.
Is it normal for a water heater to drip a little?
Brief condensation on a cold morning can be normal on gas units. A steady drip from any valve, fitting or the tank is not normal and should be checked.
How much water can a leaking water heater waste?
It depends on the source. A relief valve that runs into a floor drain can waste dozens of gallons a day without leaving a puddle. Watching your water meter with every tap off is the quickest way to tell.
Sources
- U.S. Department of Energy: Energy Saver Guide (PDF)
- Delaware Department of Insurance: Homeowners Guide (PDF)
- U.S. Consumer Product Safety Commission: Avoiding Tap Water Scalds (PDF)
- WaterHardness.org: Newark, DE water hardness by utility
- Delaware Division of Professional Regulation: Board of Plumbing, HVACR FAQs
