Protect Your Tankless from Hard Water, No Problem

Jon Hubal
02/03/2023 11:02am 5 minute read

People are ditching those old, bulky tanks for new tankless water heaters faster than ever. Tankless technology can provide infinite hot water, is much more efficient, and saves you big on your energy bill. Say you got a new tankless heater, but you have very hard water in your area, and you're worried about the health of the unit – what do you do? No need to deal with the warranty. We've got tips on how to protect your tankless from hard water.

What is Hard Water?

When someone says, "You've got hard water!" they aren't talking about your tap water giving you a hard time. They mean you have a lot of calcium or magnesium in your water. Hardness refers to the amount of these dissolved minerals in your H2O, measured in grains per gallon.

Minerals occur naturally in water, just like your body, but the amounts will vary depending on your area's geology and hydrology. That's why your hands might feel slimy after washing or why the tap tastes funny when you visit your cousin. Your tap waters have different mineral contents, and more minerals mean more alkaline (higher pH).

The hardness scale for water goes: soft (0 - 3 gpg), hard (3 - 7gpg), and very hard (7-25 gpg). You can often look up where your water ranks on your local water company's website, and local plumbers and water technicians are also good resources. Even though your municipal service should do a decent job of cleaning your tap water, they don't usually pay attention to the hardness since minerals aren't really bad for you. But they are bad for your tankless heater!

Minerals might be good for you, but those deposits build up and cause your tankless to work harder, less efficiently, and with reduced output. The harder the water, the more it will calcify on your fixtures and pipes. That's that whitish-yellow crust that forms around the head of your faucet that is so hard to clean, pun intended.

Solutions to Hard Water

Descaling your Tankless Heater

Descaling your tankless heater or any water appliance really is just part of that general maintenance we all avoid. But depending on how hard your water is, this may be essential at least every year or two. Descalers are typically chemical in nature, usually requiring you to "flush out" the system. This takes some supplies, typically a hose, bucket, pump, and whatever else the descaler recommends. An effective step-by-step can be seen here to help you descale your tankless unit.

Electronic Water Treatment

A relatively new technology, electronic water treatment is a descaling solution that utilizes sonic waves and water velocity to descale and prevent scale, a two-in-one. They've had great success with large civil pipes and have grown into the residential market – now available to buy for your tankless. They continually emit a frequency that causes sediment not to stick to the metal and causes water traveling through to knock off the current scale as well. One catch, though, is that higher water pressure is required to make them work effectively; otherwise, the scale remains and tends to build anyways.

Protecting Against Tankless Water Heater Damage

Install a Water Softener

Water softeners do just what you think they do and soften water by drawing out the minerals. This reduces calcium and magnesium buildup over time, keeping maintenance costs low and increasing the lifespan of your appliances and fixtures. Softening your water means descaling your tankless unit less often, or perhaps not at all if your water is mineral free. It also can save your heating element from going out when you least expect it, caused by damage from water deposits cracking and breaking with the temperature change.

Get a High-Pressure Tankless

If water passes through the heater fast enough, sediments aren't able to deposit, no matter how hard it is. There isn't much available science on how fast water needs to go to prevent scale buildup, but your local plumber should have a good guess based on how large your system is and how hard your water is. A higher Gallon Per Minute, or GPM, can be a great solution – but it may not be the cheapest answer. Make a cost comparison to water softening to see the difference.

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