Is your morning routine getting interrupted by a sputtering tap? Few things are more startling than turning on the faucet for a warm face wash only to be met with a violent spit of water and a loud hissing noise.
While a sputtering faucet usually indicates air trapped in the hot water line, don’t panic. In most cases, it is a harmless annoyance rather than a plumbing catastrophe. However, it is something you should address to prevent long-term stress on your pipes.
Here is the lowdown on why air invades your hot water lines and the simple, DIY methods to kick it out.
Key Takeaways
- Sputtering indicates trapped air: Irregular flow and noise are the primary symptoms of air pockets in your pipes.
- Common culprits: Maintenance work, water heater issues, or a corroding anode rod are frequent causes.
- The easy fix: mostly, opening all hot water taps simultaneously will purge the air.
- The deep clean: If simple flushing fails, you may need to drain and flush your water heater tank.
Signs You Have Air in Your Pipes
Your plumbing has a way of telling you when something is wrong. If air has infiltrated your water line, you won’t need a professional diagnostic tool to find it. Keep an ear out for these reliable signs:
- Sputtering and spitting: This is the most obvious cue. The water stream bursts, spits, or splashes rather than flowing smoothly.
- Irregular flow: You might notice the water volume surging and dropping randomly. There may also be a delay in hot water reaching the tap.
- Noisy pipes: You might hear banging, vibrating, or gurgling sounds inside the walls, often referred to as “water hammer” (though water hammer is technically a pressure shockwave, the sounds are similar).
Why Is There Air in the Hot Water Line?
To fix the problem, you first need to understand the source. While air can get into both cold and hot lines, hot water systems have unique vulnerabilities.
1. Maintenance Interruptions
The most common cause is recent plumbing work. If the municipal water supply was shut off for repairs, or if you had work done on your home plumbing, air likely entered the system when the water was cut.
2. The Anode Rod (The Hydrogen Factor)
This is a frequent culprit that many homeowners miss. Your water heater contains a “sacrificial” anode rod made of magnesium or aluminum. Its job is to corrode so your tank doesn’t.
However, as this rod corrodes, it can create hydrogen gas. If the rod is deteriorating too fast, or if bacteria reacts with it, you will get pockets of gas that cause sputtering. This is technically gas, not air, but the result is the same.
3. General Accumulation
The process of heating water naturally releases dissolved gases. Usually, these escape unnoticed. But sometimes, they get trapped at the high points of your system or the top of the tank, eventually forming a large bubble that disrupts flow.
Method 1: The “Whole House” Flush
Before you start messing with the water heater, try this simple method. It solves the problem 90% of the time.
- Turn on the hot water: Go to the faucet closest to your water heater and turn on the hot water.
- Open all other hot taps: Move through the house and turn on every single hot water outlet. This includes showers, bathtubs, and the dishwasher (if it has a manual valve).
- Let them run: Let the water run for about 5 to 10 minutes. You will likely hear sputtering as the air is forced out.
- Close the taps: Once the water flows steadily from all faucets without spitting, shut them off one by one, starting with the one furthest from the heater.
Method 2: Flush the Water Heater
If the simple flush didn’t work, or if the sputtering returns quickly, the air (or sediment) is likely trapped inside the tank itself. You will need to purge the heater. This is a good maintenance task to perform annually anyway.
1. Safety First
Turn off the power source to your water heater. If it is electric, flip the breaker. If it is gas, turn the dial to “Pilot” or “Off.” Refer to your manufacturer’s manual if you are unsure.
2. Let It Cool
This is vital. Water inside that tank can be scalding. We recommend waiting at least an hour or two for the water to cool down significantly.
Patience Pays Off
3. Connect the Hose
Locate the drain valve near the bottom of the tank. Attach a standard garden hose to the valve and run the other end to a floor drain or directly outside.
4. Open the Vents
To let water flow out freely, air needs to get in (think of putting your thumb over a straw). Open the hot water tap in a nearby sink to act as a vacuum breaker.
5. Drain and Flush
Open the drain valve on the tank. Let the water flow out until the tank is empty.
Once empty, briefly turn the cold water supply on for a few seconds to stir up any remaining sediment, then let it drain again. Repeat this until the water coming out of the hose runs clear. This clears out sediment that traps air bubbles.
6. Refill the System
Close the drain valve and disconnect the hose. Leave the nearby hot water tap open. Turn the cold water supply back on to fill the tank.
As the tank fills, air will be forced out of the open hot water tap. Once a steady stream of water flows from the tap, you know the tank is full and the air is gone. Finally, turn your water heater power/gas back on.
Troubleshooting Well Systems
If you use well water, the issue might not be the heater at all. Here are specific culprits for well-fed homes.
Faulty Check Valve
A check valve prevents water from flowing back into the well when the pump turns off. If this valve fails or gets stuck, the water drops back down, creating a vacuum that pulls air into the line. If you hear your pump cycling on and off frequently, this is a likely cause.
Call A Pro
Low Water Table
During droughts or heavy usage, the water level in your well may drop. If the pump intake isn’t submerged deep enough, it will suck in air along with the water. You may need to have a professional lower the pump deeper into the well.
Methane Gas
In some regions, naturally occurring methane gas can dissolve into well water. As the water depressurizes at the surface, the gas releases, causing sputtering.
If your water looks “milky” but clears up after sitting for a minute, it’s likely dissolved gas. While methane can be flammable in high concentrations, it is usually managed by installing an aeration system on your well tank (1).
FAQs
What Causes Air in Water Pipes?
The most common cause is plumbing maintenance that requires the water to be shut off. When the system is depressurized, air enters the pipes. Other common causes include a failing check valve on a well pump, a corroding anode rod creating hydrogen gas, or sediment buildup in the water heater.
Can Air in Water Pipes Cause Damage?
Generally, air pockets are an annoyance rather than a danger. However, violent sputtering (water hammer) can create pressure spikes that stress joints and valves over time. If the “air” is actually hydrogen gas from a corroding heater, it can be a fire hazard. If the problem persists, it is worth investigating to prevent long-term wear on your plumbing.
Why Is Only My Hot Water Sputtering?
If the sputtering is isolated to the hot water taps, the issue is almost certainly within your water heater. It could be trapped air bubbles from heating, sediment buildup, or a degrading anode rod releasing gas. If both hot and cold taps sputter, the issue is likely in the main supply line or well pump.
How Do I Bleed Air From Water Pipes?
The easiest way to bleed air is to open every faucet in your home simultaneously. Start with the tap highest up in the house (or furthest from the main). Turn on both hot and cold valves and let them run for about 10 minutes. This forces the air out of the system. Flush your toilets a few times during this process as well.
What Does Air In Water Pipes Sound Like?
Air in pipes usually sounds like hissing, popping, or banging. You might hear a loud “thud” when a valve closes (water hammer) or a vibrating noise inside the walls when a tap is running. If the flow is sputtering, it often sounds like a coffee maker finishing its brew cycle.
Will an Airlock Clear Itself?
Small air bubbles often clear themselves with normal water usage. However, a significant airlock acts like a blockage and usually won’t go away on its own. You need to actively flush the system by running multiple taps or bleeding the specific line to restore proper flow and pressure.
Final Thoughts
Trapped air in your hot water system is frustrating, but it’s rarely a disaster. If you notice the sputtering is limited to the hot side, your water heater is likely the culprit, whether it’s simple trapped air or a gassy anode rod.
Start with the easy fix: open all your taps and let the system breathe. If that doesn’t work, a good tank flush usually does the trick. Now that you know how to silence those noisy pipes, you can get back to enjoying a peaceful, steady shower.
