Do tankless water heaters leak?

Tankless water heaters don’t store any water in them. They heat water on demand. As such, water leakage is near impossible. However, after several years of usage, it is possible that the piping and joints may start leaking.  This means that despite the fact that it is rare for these tanks to leak; there are chances of leaks.

Mostly, in case it happens, tankless water heaters leak from the bottom or along with the connections. It may seem not a big deal at first. However, as time goes, the leakage may turn out to be catastrophic if not taken seriously.

Water leaks from your water heater are a symptom of a much bigger problem in wait. It’s important that a professional do a checkup. If possible, it’s always good to engage an expert from the manufacturer or a professional.

The little drops may cause significant damage to your floors, walls, and roofs. If not handled immediately, these leakages may trigger bigger problems, which may be too expensive to manage. As such, it’s always important to act fast.

A temporal solution might be installing a drain pan before a permanent solution is sought. A suitable drain pan helps in containing 100% of leaked water. It helps in preventing your floors and walls from damage. The drain pan acts as a conveyor where water is removed without causing damage to floors or walls. Needless to mention, a drain pan saves the cost of structural repairs and also inhibits the growth of molds.

However, do know that this is just a temporal solution to buy you some time. It’s rendered useless if there is a total failure of the water heater.

What causes water leakages in tankless water heaters?

Improper venting

Proper installation helps in minimizing these leakages. Improper venting is a well-known culprit in leaking tankless heaters. Proper venting helps in ensuring that no condensation goes inside the water heater. In case this happens, the leakage might occur or worse still, the entire system may fail.

Venting is done through the wall or roof. If possible, make it short. This will not only save on cost but also minimize the occurrence leakages through the pipe and connections.

Importantly, always follow the manufacturer’s instructions on the venting process.

Gas Piping

People prefer tankless water heaters for they save energy. At times, the existing gas pipe may not be enough to supply the right amount of gas for the system to function. Ensure a separate gas line run to the water heater from the meter without re-running the entire gas main. Reduce the number of joints when installing. This will reduce the chances of gas leaks.

Worth noting, a gas leak is an emergency phenomenal and should be handled by a licensed expert only. You can tell whether there’s gas leakage either by smell or by applying soapy water to suspicious areas.

Water pipe connections

Most water tanks come with a relief valve. A few ships without. Relief valves are usually located on the hot water outlet (pipe leaving the heater to your fixtures). They are necessary especially when flushing or draining the tankless system. These valves reduce water leakages through joints. They also have union connections for smooth and speedy replacements. Ensure you get a kit with a proper relief valve for your heater’s size.

Acidic and hard water

Hard water has dissolved particles that build up in the piping system after some time. These buildups affect heat exchanger and may lead to overheating. When this happens, the system will automatically lock and send an error code to the control panel. If the system is reset without correcting the error, it’ll still close again until the problem is solved first. Forcing the system to work without proper diagnosis may lead to system failure.

Acidic water, on the other hand, affects metals in the plumbing system. It causes “pinholes” in the tankless water heater which may promote leaking with time. The level of PH in the water determines how fast acidic water will damage your system. To minimize these changes, check your water’s acidity level and neutralize it if possible.

High water flow rates

Tankless water heaters work well with low flow rates and low water pressure. A flow rate of 5 GPM is suitable for a residential application with a pressure system of 30 PSI. It’s easier to correct issues with a lower flow rate than when it’s high. Debris in the showerhead or faucet aerators should be checked regularly since they may cause the heater to fire up.

What to do when your tankless water heater leaks

The following are possible remedies for leaking tankless heaters

Replacing or repairing

Take action when you realize that your tankless water heater is leaking. The magnitude of leakage will determine what action to take. Have a professional plumber to check your system and give the right diagnosis. A professional plumber will tell whether you can do repairs or you need a full replacement.

Installation of Drain Pan

If your tank location is in the house, take precautions and prepare for leaks. This is so that in a case of leaks, your property will be safe. One of the best ways to mitigate leaking hazards is by installing a drain pan. In a case of leakages, the water will flow into your house and may affect your property, but with a drain pan, you will easily note and damages will be minimal.

Contact the manufacturer

Most manufacturers offer a warranty on the heat exchanger and other parts of the heater. If your water heater starts leaking before the expiry of the warranty, contact the manufacturer for replacement. Most of the warranties tend to be half the life expectancy. Be careful not to do anything that will make your warranty invalid.


Like any other water heating system, tankless water heaters need regular service and maintenance. Make sure a professional plumber services your system on a regular basis. This will help you to detect leakages earlier and have counteractive solutions in place.

Most importantly, let a licensed contractor do the installation and the servicing to avoid nullifying the warranty.

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