Why Noritz Tankless Water Heater Leaking [Reasons + Solutions]

Your Noritz tankless water heater leaking due to any of the following reasons:

  • Improper installation
  • Blocked pipelines
  • Accumulated sediments
  • High water flowing
  • A faulty venting system, and so on.

Whenever there is a leak in your unit, check for loose pipe connections and tighten them. Also, it is recommended to adjust the water pressure in the system. Overall, install the heater as per the manufacturer’s instructions to reduce the risk of leakage in your Noritz water heater in the future.

noritz tankless water heater leaking

Fortunately, we have explored all the reasons that lead to leaks and shown their effective solutions. So, go through the article and solve your heater’s leakage problems instantly.

Table of Contents

Noritz Tankless Water Heater Leaking [7 Easy Solutions]

Here, we will find out the most common reasons why your Noritz tankless water heater is leaking and guide you on how to solve them easily. So, let’s scroll down.

Note: You can also read how to fix the Noritz tankless water heater with no display problem.

1. Faulty Installation

A faulty installation is primarily responsible for leaking your new Noritz tankless water heater. The best chances are you have poor water pipe connections or the water supply lines are not securely connected.

If so, the entire water supply may fail and causes leaks to your Noritiz tankless water heater.


If you find that the water dripping from the bottom of the heater issue, first do the followings:

  • Isolate the heater from the power connection. Also, turn the gas valve to the off position.
  • Shut off the cold and hot water supplies (if you have isolated valves).
  • Remove or drain storage water from the unit by the isolator valve on the bottom of the heater. To do so, remove the black plastic drain plug from the bottom to drain the water.
  • When done, inspect all the connections and join parts of your water heater for leakage. 
  • Tighten unsecured parts or replace the bad ones. Overall, ensure that your tankless water heater is installed correctly according to the manufacturer’s instructions. For instance, you can take some help from your local plumber.

2. Accumulation Of Sediments

The accumulation of sediment is the next culprit that causes the leaks with the Noritz tankless water heater. 

Building up sediment in the water pipelines is mainly related to the hard water that is running through your plumbing system. You may face this acute problem if your living area contains hard water.

Bad or hard water bears naturally occurring minerals like magnesium and calcium, which eventually accumulate in the piping system and create deposits.

At times, the acid water creates a pinhole in the pipelines and causes a leak. Also, this ongoing acidic water will have a negative effect on the heat exchanger of the heater. 

As a tankless water heater has no tank to the reservoir, it heats the water directly through a heat exchanger. With sediment buildup, the heater exerts significant pressure on the heat exchanger, affecting its configuration and causing a leak. 


When you get a bad smell or acid water after turning on your heater, it is warning you that the scale builds up in your heater and you need to flush or drain your unit to get rid of these sediments. Here you can watch the tutorial to know how to flush your heater pipelines.  

Clear out your heater pipelines and pumping system at least twice a year. Or, the best solution is to install an acid neutralizer that will help raise the water PH.

Note that, the neutralizer should be installed at a point where it interacts with the water before entering your household plumbing system. Hopefully, it will prevent pinholes and cracks in the plumbing system of your tankless water heater.

Besides, you can install a water softener to minimize or prevent leakage. Actually, it also helps to eliminate calcium, magnesium, and other minerals from the water before it enters the piping system of your water heater.

If you are not good at installing water softeners or acid neutralizers, call a certified plumber to install them safely.

3. Defective Venting System

Another common cause of Noritz tankless water heater leakage is a faulty venting system in your tankless water heater. Normally, the venting system goes through the roof and the walls to ensure optimal performance for your water heater.

noritz tankless water heater defective venting system

A proper venting system installation ensures that there is no condensation going through the water heater. And, it helps in minimizing leakages.

But without proper venting, the heater may drip or leak into the system, and then you’ll smell incomplete combustion of gas. Finally, it may stop the entire operation.

On the other hand, water is dripping from the bottom of the Noritz water heater, which hints at an internal leak or rain water has entered through the exhaust vent.


Inspect the venting system of your water heater to ensure it is installed correctly through your wall or roof. If it is not secured, you can expect to get condensation leaking out of your water heater. Overall, try to shorten the venting pipe if it is set to high. 

Next, check for blockages in the vents and clear them. The process will save you from leakage through the pipelines and the connections. If needed, seek professional help to perform your task.  

4. Too-High Water Pressure

A high water flow rate or pressure is the next major cause of your Noritz tankless heater heat exchanger leaking water. A tankless water heater heats the cold water with the heat exchangers and supplies hot water to the pipes directly.

too high water flowing

The Noritz tankless water heater performs well with a 5 GPM flow rate and a pressure system of 30 PSI for residential areas.

The heater is designed to work well with a low flow rate and low water pressure. But, high flow rates and high water pressure lead to leaks in your water heater.

As a result, you may face your Noritz tankless water heater with no hot water. However, here is an easy tip to fix the problem.


First, check for water pressure in your water heater using a pressure gauge. If it is too high, adjust the water pressure from the water pressure regulators. The regulator will have a screw on the top. Turn the screw counterclockwise to decrease water pressure. If needed, replace the bad regulator. 

Along with all the above, check for debris and rust in the showerhead and faucet areas. If you find any debris, clean the accumulated debris completely from the faucet aerators as a part of regular maintenance. The process also protects you from being fired up by debris.

5. Blocked Inlet & Outlet Pipes

A blocked outlet and inlet pipes are also contributing factors to leakage with your Noritz tankless water heater.

Tankless water heaters draw power either from electricity, gas, or propane. So, it requires an extra exhaust pipe connection to expunge the poisonous gasses from the exterior house.

Unluckily, if there is gas leakage, it may happen due to the pipe connection getting loose.

Plus, birds can build nests in the exhaust pipes. Over time, the rodent or the bird’s nest might clog the exhaust pipelines and causes leaks. However, you will get an alert error message for such occurrences to repair the gas leak.


  • To check for gas leaks, turn off your water heater first. Keep the gas shut-off valve in the off position.
  • Check the exterior exhaust (inlet and outlet) pipes for blockage. If you see rodents or birds have clogged the pipeline’s nests, remove them entirely.
  • Yet, if you get the error code again on your control panel for your water heater, call a professional plumber to fix leaks in the gas lines.

6. Relief Valves Problems

The relief valve is an essential part of the Noritz tankless water heater, installed on the hot water (outlet) discharge pipe that allows you to supply the rest of your water fixtures.

noritz tankless water heater relief valves problems

Basically, the valve is a safety measure that keeps the water pressure coming into your house at a safe level. The higher chances are the pressure relief valve is leaking or dripping. 

This mostly happens due to improper adjustment of the valve. Plus the valve may be triggered to open due to excessive temperature or the valve is defective itself and causes leaks. 


  • To fix the issue, first, inspect the valves for leakage. Ensure it is well tightened to reduce the risk of leakage.
  • If the pressure release valve still drips due to its fault, replace relief valves immediately.

7. Gas Supply Issue

People love tankless gas water heaters as they save energy. It can perform best when there is enough gas supply. Because of certain factors, the existing gas pipe may fail to supply the right amount of gas to run the function. At times, you will encounter leaks from gas pipes. 

noritz tankless water heater gas supply issue

Several factors would be responsible here like insufficient gas pipes or the gas lines are not installed correctly. 


To minimize the chances of gas leaks, try to minimize the joints when setting up. If needed, ensure a separate gas line has run to the water heater without re-running the main gas entirely.

Dealing With Gas Leaks:

A gas leak is an emergency phenomenon. So, only an expert plumber can handle the gas piping system to reduce the risk of leaks. 

Maintenance Of Noritz Tankless Water Heater

You should take care periodically of your tankless water heater to minimize the risk of leakage, both internal and external. Let’s follow some effective steps on how to keep your water heater fit for long usage.

maintenance of the noritz tankless water heater
  • Have a visual inspection of the combustible materials.
  • Listen deeply if it is making any sound during the operation.
  • Wipe the surface of the heater along with the remote control with a wet cloth, then let it dry.
  • Apply a neutral detergent to clean it.
  • Check for dust and soot in the exhaust and clean and brush debris so that air can flow through the system.
  • Inspect periodically the control valves if it gets leaked and verify everything is fitted correctly.
  • Even if you notice any broken or defective parts, replace them immediately to avoid the next risk. 
  • Hopefully, you won’t face leakage issues with your Noritz tankless water heater soon.


How does a Noritz tankless water heater work?

The Noritz tankless water heater draws cold water from the supply line and inflows it into the high-power burner and passes through the heat exchanger. This mechanism enables us to give you instant hot water.

What can I do right after an electric water heater starts leaking?

You should switch off the breaker to the water heater and turn off the valve that supplies water through a hose to the drain on the bottom of the heater. Call a plumber to repair it.

Could you repair a leaking tankless water heater and how?

Yes. Most leakages are repairable by yourself. A corroded pipe is maintainable, but corrosion that leads to a leak in the heat exchanger is irreparable and needs to be replaced. Install a water softener to prevent leaks.

What is acidic water with a water heater?

Acidic water (PH 6.5 or below) contains corrosive properties that lead to pinholes in the pipelines and eventually lead to a leak. Eventually, it will wreak havoc on your water heater’s piping function.

What might happen if you ignore the leak in the tankless water heater?

A tankless water heater also leads to leaks at the bottom or along with connections. First, it may seem like no big deal at all, but over time, the leakages can cause catastrophic failure if not considered seriously.


Already, we have explored all the culprits behind your Noritz tankless water heater leaking and guided you on how to fix the issue.

So, follow our above guide on tankless water heater leaking issues whenever you struggle to solve your water heater’s leakage problem.

Yet, if you encounter any other issue with dripping or leaking, let us know in your comments. We will come to you as soon as we can.

About William

William is the founder of Fireplacehubs.com. He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

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