Why Tankless Water Heater is Leaking : 5 Reasons

Tank heaters must provide the discretion or space management that tankless water heaters offer. Compared to its competitors, they also last longer and use less energy. Although they are tankless, they still have a chance of leaking. Here are a few causes of tankless water heater leakage.

Leaks in tankless water heaters are typically the result of poor installation. If installed incorrectly, a tankless water heater might leak due to faulty pipe connections, a flawed venting system, or an excessive water flow. Blockages in the pipes or mineral buildup from hard water can also cause leaks.

This article will first examine the operation of tankless water heaters before exploring the most frequent causes of leaks.

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What Leads to Leaks in a Tankless Water Heater?

Tankless water heaters are thought to be leak-free by consumers. Since this form of heater does not have a tank, most of us assume it won’t leak.

But according to common sense, a tankless water heater is still susceptible to leaks since water will eventually pass through it, even if it may not have a water reservoir.

The unit with a high-power burner will receive cold water from the main plumbing supply line, which will then run via a heat exchanger. This system allows the appliance to provide quick hot water when required.

Most licensed plumbers will tell you that faulty installations are frequently to blame for leaks within the first or second year of a product’s lifespan. Additional factors include:

unfavourable water quality (hard or acidic water)

  • improper venting
  • High water flows
  • pipes for gas
  • plumbing connection¬†

The good news is that a tankless heater will only leak about 1 GPM (gallon per minute). In other words, compared to what you may anticipate from a tank heater, the damage to a house is far less.

However, installing a drain pan in addition to your tankless water heater is always a smart idea. If it leaks, the drain pan will catch the water and guard against property damage until your plumber can stop it.

Even though you hope the water heater won’t ever leak, adding a drain pan is a smart safety measure in case leaks occur at any time throughout the water heater’s lifespan.

It’s important to note that a tankless water heater can serve you for its useful life without leaking, provided it has been installed appropriately and is kept up with regularly.

The reasons a tankless water heater will leak have previously been covered. Let’s investigate those causes in more detail to see how they occur and what may be done to prevent them.

1. Poor Water Quality

Tankless water heater owners and operators of residential and commercial buildings must know the status or quality of the water flowing through their plumbing system. This is crucial because, if the problem is not fixed, hard or acidic water will inevitably harm your heater.

Calcium and magnesium are dissolved mineral sediments found in hard water that will eventually build up in the pipe system.

How does your tankless water heater respond to hard water?

So, when the mineral sediments build up, some end up in your tankless heater. They cause the heat exchanger to overheat, compromising its ability to work properly.

Your heater will lock up due to overheating and issue an error code to the control panel.

The same reason that wears out the pipes in your tank water heater unit and finally causes pinholes that inevitably become larger with time and lead to leaks is the accumulation of mineral silt.

Your plumber will drain or flush the system to remove any built-up silt.

You should install a water softener in your house to stop or lessen the risk of leaks being caused by this issue. You may achieve it with the assistance of your plumber.

Yellow or brown water flowing out of your faucet whenever you turn on the water is one of the signs of mineral buildup in your tankless water heater and pipes.

This issue may be resolved by installing a water softener since softeners are made to efficiently remove calcium, magnesium, and other minerals from the water before it enters your plumbing system and tankless water heater.

Leaks in tankless water heaters

Why Is Water Acidic?

Acidic water is defined as having a pH of 6.5 or below. The pH scale ranges from 1 to 14, with 7 representing a neutral pH level. Additionally, water with a pH above 7.5 is probably alkaline or basic.

Acidic water is corrosive and will cause severe damage to your pipes, especially those in your tankless water heater. This will eventually cause leaks and pinholes in your pipework.

You should be able to identify acid water as the source of any blue-green stains that your water occasionally leaves on your bathtub, drains, faucets, and the area surrounding your sink. Your copper and aluminium pipes are also deteriorating, so that’s another consequence.

The answer to acid water is to install a whole-house acid neutralizer. Calcite, which effectively raises the PH of the water, is used as an acid neutralizer. Before the water reaches the plumbing system in your home, the acid neutralizer is put where it may interact with the water.

That ought to successfully thwart the development of pinholes and fractures on the pipes in your home’s plumbing system, including those in your tankless water heater.

2. Ineffective unit venting

Your tankless water heater’s venting is carried out through the ceiling or a wall. For optimum efficiency, it is essential that the venting be carried out under the manufacturer’s specifications.

Properly installing the venting systems largely prevents condensation that might lead to leaks into the tankless water heater. Condensation may result in system failure because the water interferes with the appliance’s ability to operate properly.

3. Connections to Water Pipes

Extreme caution should be used when installing water pipes for a tankless water heater.

Options for tankless water heaters include a relief valve that is situated on the hot water output line that serves the rest of your home’s fixtures. Check to see that the valve is securely tightened.

Without a release valve, tankless water heaters are more likely to leak. This is because pipe jointing does not receive any relief as pressure increases. Relief valves are also useful to drain or flush the tankless water heater.

Ensure the water heater has a release valve to ensure water leaks are avoided or kept to a minimum. If it doesn’t, your plumber should be able to locate one that will fit your unit and be correctly installed.

4. Obstructed Outlet and Inlet Pipes

Your tankless water heater may experience leaks other than water, which might be problematic or dangerous.

This kind of heater can be powered by electricity, propane, or natural gas, among other energy sources. If your appliance is powered by natural gas or propane, it must be connected to an exhaust pipe so that toxic combustion byproducts may be vented to the outside of the building.

Due to weakly connected pipes, gas-powered tankless heaters may encounter severe gas leaks.

Additionally, a rat or bird trapped in the pipe from the outer exhaust pipes may obstruct it.

Birds frequently construct nests in exhaust pipes, which effectively obstruct them.

Fortunately, tankless heaters fuelled by natural gas or propane will have an incorporated safety function that notifies you of such abnormalities by sending an error message to the water heater’s control panel.

It would be best if you then got in touch with a qualified plumber to address the problem. The control panel will notify you of any gas line leaks so that you can act quickly and appropriately.

5. Rapid Water Flows

Tankless water heaters are made to operate at their peak efficiency, even under conditions of low water pressure and flow rates.

Your water heater may develop leaks due to excessive flow and high water pressure.

This implies that if you live in a residential area, you should ensure that your unit has a flow rate of about 19 GPM and a pressure of not more than 30 PSI.

Users are urged to frequently clear away and clean any debris that may build up on the faucet aerators and showerhead as part of routine maintenance. By doing this, you avoid having the heater fire up prematurely due to debris.

EcoSmart ECO 18 Electric Tankless Water Heater, 18 KW at 240 Volts with Patented Self Modulating Technology

EcoSmart ECO 18 Electric Tankless Water Heater


My tankless water heater should be dripping.

It shouldn’t be dripping if your tankless water heater is operating properly. The sole exception is if a drop is present at the relief valve due to increasing pressure inside your water heater. Any more drips or leaks will result from one of the abovementioned causes.

Although, as we previously indicated, you don’t anticipate your tankless unit to leak, installing a metal drain pan as a precaution is preferable.

A proper and high-quality drain pan can contain leaks throughout the tankless water heater’s lifespan.

A drain pan may also be used to securely reroute leaks from your property. As a result, it can help you avoid spending thousands of dollars on structural damage from leaks or mould and mildew.

Can You Fix a Tankless Water Heater That Is Leaking?

Any leakage problems may be identified early and fixed with reasonably priced fixes by performing planned maintenance. Most leaks can be improved, and your plumber will advise on the ones that can’t.

While loose valves and connections can be tightened, rusted pipes must be replaced.

The heat exchanger must be replaced if corrosion results in leaks since it is frequently irreparable.

The need for repairs may be significantly reduced by taking preventative steps like installing a water softener in your house if your water is hard or neutralizing acidic water with an efficient acid neutralizer.

What Is a Tankless Water Heater’s Life Expectancy?

Your heater should last between 12 and 20 years with the correct installation by a qualified specialist. Following the manufacturer’s suggested maintenance program will extend the life of a tankless water heater.

Most tankless heaters also include a warranty that typically lasts half the bought device’s duration. You want to follow the maintenance schedules for the heater’s lifespan and avoid doing anything that will void your warranty.

In this manner, even if a warranty-covered component fails, you may still benefit from manufacturer assistance.


Tankless water heaters are constantly improving and becoming more effective at conserving energy.