Skip to main content
Water Heater

Why Is My Tankless Water Heater Leaking

By April 8, 2022No Comments
In-home tankless water heater

Believe it or not, a tankless water heater can leak. Any item in your home that deals with water have the possibility of leaking. Water naturally erodes and corrodes various pipes and materials. Also, water has naturally occurring metals in it that when in contact with other metals can create a chemical reaction that is degrading to the pipe or material. Why is my tankless water heater leaking? One reason is poor connections. Water flows through the pipes and the connections could eventually leak. Have your plumbing system checked regularly.

Let’s take a look below at all of the possible reasons for a tankless water heater to leak.

What Is A Tankless Water Heater

The tankless water heater is often installed in commercial buildings or homes that have limited storage space. It is wall-mounted and has a few pipes running into and out of it. Additionally, the purpose of the tankless water heater is to heat any water that flows through it and send that water back through your pipes for a hot shower or dishwasher, or washing machine.

The goal here is to lower your energy costs, provide an unlimited amount of hot water, and last longer than your storage-tank water heater. Tankless water heaters do not wear down as fast because they don’t have the stress and pressure build-up of water in the tank. They work less because they don’t store water, so their parts last longer.

Garage wall-mounted tankless water heater.
Garage wall-mounted tankless water heater.

Why The Leak

There are a variety of ways that a tankless water heater may be leaking. Although water isn’t stored in a tankless water heater, it does pass through it. So, leaking is always possible. Here’s how:

  • Venting Fail – improper venting can cause leaks. Make sure that the venting is done properly through your wall or roof. Also, always keep the vent as short as possible. Venting ensures that condensation does not go inside the water heater. Lastly, it saves on costs and minimizes the potential for leaking pipes or connections.
  • Gas line – making sure that the proper gas line is installed is key. Minimize the number of connections and joints that you have running off your main gas line. Providing the right amount of gas for the system to function properly is vital to its success and longevity. Gas leaks require professional assistance and immediate shut-down of the equipment.
  • Water connects – relief valves are the most important part of limiting your tankless water heater leaks as the valves allow you to flush the system or drain the pipes properly. Your relief valve is typically located on the hot water outlet.
  • Acid water – acidic water can eat away at your systems metal and plumbing. Pinholes can begin to form and allow water to leak out of the system. Do your best to reduce the acidic levels of your water so that your system can maintain its functionality.
  • Hard water – hard water contains mineral deposits that can buildup in your system. This causes a system shut-down. You will notice an error code that messages you what the issue is. Make the repair and clean the pipes prior to attempting to restart the system. Failure to make the necessary repairs could cause long term damage to your system.
  • Increased flow rates – the goal for a tankless water heater to work efficiently is to have a low flow rate of 5 GPM with a system pressure of 30 PSI. If you tankless water heater exceeds these numbers you will need to conduct maintenance on your shower-head and faucet aerators. High pressure can cause damage to the tankless heater and heat exchanger.
Outside wall-mounted tankless water heater.
Outside wall-mounted tankless water heater.

How Do I Prevent This

The best way to prevent your tankless water heater from leaking is by conducting the recommended maintenance as provided by the manufacturer. Everything has longevity and a tankless water heater is no different. You should consider installing a drain pan underneath just in case of a leak. Currently, it is expected that a tankless water heater can last 12 to 20 years long. Now, the longevity of this item is only as long as it is regularly maintained.

How Much Do They Cost

The price of a tankless water heater varies based on the needs of the home. You could purchase an electric tankless water heater, a solar tankless water heater, or a gas tankless water heater. These costs can also vary based on the size of the unit that you will need to purchase.

Electric tankless water heaters range from $100 to $1,500 and gas tankless water heaters are $200 to $2,500. Solar tankless water heaters can reach up to $5,000 and even go as high as $13,000. These costs are going to vary based on your location and hourly installation rates by your local master plumber.

The average cost for a tankless water heater repair is $650 and has a range of $350 to $950 depending on where you live and what the repair needs are.

Other Recommended Maintenance

While you are tackling the tankless water heater project, go ahead and read up on your pipes. Understanding which pipes are meant for which project is necessary for success. You wouldn’t want to use the wrong pipes and end up with huge expenses later on. Keep in mind that with a tankless water heater, you are likely going to see copper pipe as well as CPVC, and PEX pipes used.

Next, it is a great idea to gain knowledge about how your tankless water heater works. There are parts and pieces that make up the tankless water heater, such as the TPR valve, that might need replacement someday. Knowing what those parts and pieces are can save you time and money.

Lastly, it is a great idea to learn about making your hot water last longer in your home. There are various reasons why you could be taking colder showers or noticing the water not staying as hot for as long as you like. Always consider reading up on the reasons why your hot water isn’t lasting too long.

Tankless water heater repair.
Tankless water heater repair.

When Do I Call A Professional

Always contact a professionally licensed master plumber when you are dealing with new plumbing projects or making repairs to old plumbing projects. Use professional plumbers for any of your plumbing needs.

Also, they will be able to tell you if your tankless water heater is in need of replacement parts, or if you need to replace the entire unit. Like a tank water heater, parts do corrode and break. Finding the most reputable professionally licensed master plumber is key.


Finding a master plumber for your tankless water heater needs can be a tough task. Reach out to your local home inspection team first. Not only can they conduct a full home inspection of your plumbing needs. They can also provide you with the most reputable master plumbers in the area. Call on Avalon Home Inspections, we conduct home inspections in Greenville, SC, and Atlanta, GA.

Leave a Reply