Hard water is still liquid; it’s the mineral deposits that make it “hard”. You’ll find magnesium, Calcium, Manganese, and silicone among other elements within this type of water. This specific type of water will damage your water heater if you’re not careful.
How?
I went into detail about the process in the next bit of the article that I wrote. Although normal heaters take damage and lose their efficiency over time, the best water heaters for hard water are the answers to all your woes. Yes, they are water heaters. But they are specially designed to counter mineral-filled liquid.
Now, the big question is… “Where to find these things?”
“In this specific article,” would be the answer. I’ve also tucked in a buying guide at the end just to help you find alternatives should you choose not to go with my recommendations.
Table of Contents
Do I Really Need a Special Water System for Hard Water?
We all know, every matter has 3 states; solid, liquid, and gas. But when it comes to water, the term ‘Hard Water’ does not mean its solid form or ice.
Instead, hard water simply means water that is high in mineral content. As water comes to your tank through a long journey through the ground, it brings about minerals such as limestone and chalks with it, which dissolve easily in it, but later gather at the bottom due to gravity.
Now the question is how to tell if you have hard water? There is a simple way of knowing this is. Check if your soap lathers up with a lot of foam and washes up easily, or leaves you with soap scum all over the place. If you get an adequate amount of foam, then your water is good to go. If not, then you have hard water.
Hard water, or high mineral content water although it doesn’t affect the quality of the water flowing out of your tank or doesn’t harm your health in any way.
But… it has the potential of gradually damaging your water heater and bathroom fittings. But do not worry; there’s a solution for preventing this from happening. Yes, you’ve guessed it- the best tankless water heater for hard water.
Top-Rated Water Heaters/Systems for Hard Water
When it comes to hard water, normal water heaters or systems won’t do. You need to go to specialized products. In this section of the article, I’ll be telling you about my recommendations when it comes to the best water heaters for hard water or full-fledged systems. Let’s get on with it, shall we?
1. EcoSmart ECO 11 Electric Tankless Water Heater
Needless to say, tankless water heaters do not have any place for storing water. They heat the water that is directly provided to them from your plumbing system. They are point-of-use water heater solutions that you plug in, and start using right away.
Since they are electric, you don’t have to worry about the gas and stuff. They run completely on electricity. And of all the electric tankless water heaters I have used so far, the one that made a lasting positive impact on my life is the EcoSmart ECO 11 Electric Tankless Water Heater. You can read a brief comparison between tankless vs tank water heater.
You must be thinking, “How being tankless can help you protect your water heater from hard water?”
Well, it’s a simple process. Limescale deposits dissolve quickly into water and mix with the groundwater that flows into your tanks. But after getting to the tank, the water slows down a bit for the heater to heat it up to your requirement.
Meanwhile, the limescale and calcium deposits get pulled down to the bottom of the tank by gravity and get stuck there. This causes chemical reactions inside the tank that eventually damages the tank and affects the water heater.
So, the best solution for limescale problems in the tank is to go tankless. No limescale deposit can damage your tank if you don’t have a tank in the first place, right?
But there is a catch. Not all types of water heaters can go tankless. The best electric hot water heater for hard water helps you get rid of its dependency on the tank.
The EcoSmart Eco 11 is a brilliantly designed and the best electric water heater for hard water that does everything you’d expect from a product such as this while being completely tankless. You can set it up at any place where there is a faucet or a showerhead, and the heater will heat the water flowing from it.
This will not only help you fight limescale deposits but will also help you save water and electricity by a huge percentage in comparison to its other counterparts.
This thing is great in day-to-day activities as well. Eco Water Tank helps with quick water heating and saving space. While doing that, this little product saves you some space and energy as well.
You get the basic perk of saving electricity with it too. This is all thanks to the “Self-Modulating” technology that adjusts the temperature according to how much it needs at a point of time. This thing is an environment-friendly device to the core. It will cut down the heating cost for water as well.
2. Bosch Electric Mini-Tank Water Heater
If you’re really not sure about tankless water heaters and at the same time, don’t want to give up so much space to tanks, here’s a good option for you: The Bosch Electric Mini-Tank Water Heater.
It has a mini-tank in its name, so it doesn’t need saying that it comes with a tank, but a much smaller one than usual.
It is a hardwired electric water heater that gives the tankless water heaters tough competition despite having a tank of its own. And not just that, the tiny little monster has the capacity of heating water at a maximum temperature of 65°F – 145°F, at 12A / 120V of electricity. And it is one of the best tank hot water heaters for hard water.
And speaking of efficiency, this water heater has a water pressure range of 1 – 150 psi with a pressure relief valve included. The storage tank may be small in size, but it can store up to 7 gallons of water. While keeping the whole thing compact.
I have to tell you about this new feature this thing is equipped with. It has a unique thick CFC-free foam insulation which maximizes energy efficiency better and quicker. And the tank is glass-lined, which ensures a long-lasting life and quality performance.
The compact design of this water heater will allow you to mount it on the floor, or the wall, whichever suits your interior best. And if you’re still not satisfied with the design, it comes in two other size variants, 4 gallons and 2.5 gallons.
Both are equipped with the same functions and technology to meet all your demands. Here’s a little perk of using this thing that you may come across if you use it for a certain period of time. You might notice that the tank has started leaking. Well, I thought the same.
But later on, I found out that there is no leak at all in this Bosch water heater. It’s actually the moisture that had escaped the valve and started gathering at the brim of the tank.
This happens in rare cases if the pressure release valve is not linked to the drainage as instructed. An easy way to prevent this from happening is to use an additional drain pan or vessel to release the pressure. That’s only a minor inconvenience. But other than that, the heater is top-notch.
3. 3M Aqua-Pure Whole House Scale Inhibition Inline Water System
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Enough about water heaters, let’s talk about an inline water system that pledges to help you fight scale buildup no matter what kind of water heater you use. Scale is calcium and magnesium deposits that often form when hard water is heated.
Hard Water is responsible for most scale formation in pipes, water heaters, finishes, and flat surfaces, and other water-using appliances. Over time scale build-up can significantly shorten the life of any water-using appliance.
Also, scale buildup inside pipes causes loss of water pressure as the interior gets smaller and smaller over time.
Let me present to you the 3M Aqua-Pure Whole House Scale Inhibition Inline Water System AP430SS. A fine little tool that is designed to prevent any sort of scale development in your pipes or tank, no matter how hard the water is. Come and have a closer look at it.
First things first, let’s get to the dimensions of his thing. You probably have noticed how small this thing is. I mean, seriously, it’s no bigger than my can of deodorant! It’s just 2.8 x 2.8 x 13 inches in dimension and weighs only 1.9 pounds, which makes it ideal to carry around and fit into any sort of interior.
Well, it contains polyphosphate that prevents any scale buildup in your tank. And don’t worry about safety; this thing is tested by NSF International to NSF/ANSI Std. 42 and has been certified to be safe.
Material is an important factor when it comes to buying the best water heaters for hard water (or the entire system). You gotta be extra careful and recheck everything twice.
Not with this thing. This inline scale inhibition water system is made from the finest 304 stainless steel and corrosion-resistant materials that are ideal for use with copper pipes in your home.
If we break it down to numbers, the specifications of this tool will blow your mind. For a tiny little thing, as it may seem to be considering its size, it has the capacity to sustain in flow rates as high as 10 GPM, and has a pressure range of 25-125 PSI (862 kPa), with an operating temperature of 40-100F (4.4-37.8C).
The package comes with a 3M Aqua-Pure AP431 that is easy to replace. The AP431 can be adapted to various pipe sizes by using a reducing adapter on either end. Installation fittings can be sweated or threaded.
4. Corro-Protec CP-R Water Heater Powered Titanium Anode Rod
While we’re at it, let me tell you that inline anode rods are a thing now. Almost every home has one. And they do more than just prevent scale buildup. For instance, check out the Corro-Protec CP-R.
What makes it special among its counterparts is that while most other inline anode rods just prevent limescale from developing inside your plumbing, this little baby eliminates the terrible odors that develop inside your system caused by hydrogen sulfide.
While it may look like a humble little anode rod, it has the potential of providing your water system a permanent protection from corrosion.
No matter how hard the water is, this has the capability of defending your system from it, and can easily replace your 40-80-gallon water heater’s hex head anode rod.
The design of this thing is also a big saver for energy. This is one of the best water heater for well water as it deals fine with high mineral content. It reduces mineral accumulation in the tank which on one hand improves the water quality, and on the other, reduces stress on the tank which eventually reduces energy costs.
This product extends the life of your reservoir by forming a protective layer on the walls and providing the water heater with permanent protection from rust and corrosion. This happens because of the high electron levels that the product undergoes during the making of it.
Installing this thing is super easy. The package comes with a step by step instruction sheet which is easy to follow even if you are a complete novice. I did it all by myself for the first time without anyone’s help simply by reading the instructions!
The anode rod reduces limescale deposits in your system such efficiently that it minimizes the risk of clogs, breakage, slow water output, damage, and even premature wearing out which ensures safety and efficiency in the long run.
These anode rods are manufactured and packaged in America, ensuring a North American quality and a 20-year warranty.
5. InnoMax Thermal Guardian Quantum Solid State Waterbed Heater
Don’t you just love waterbeds? Well, I do! Nothing like a well-heated, cozy waterbed that would keep you warm as you float over the cold water of the pool on a hot summer drink.
A lot of people enjoy swimming or sunbathing, but this is hands down my favorite pool activity and I do it almost every weekend. And the best way to keep the temperature of your waterbed well balanced is a good heating pad.
Here is a heating pad that has caught my attention with its quality performance, and I assure you it’ll catch yours even if you aren’t a big fan of these. They have named the product ‘thermal guardian’, and I dare to say it is no exaggeration to call it so. It’s an 18-gauge waterbed heater with a 6 feet long cord that has the capacity of working under waterbeds as shallow as 9 inches.
The heater pad is equipped with 32 different settings that allow you to set the heat to the temperature which is perfect for your level of comfort. The state-of-the-art electronic control panel can hold the temperature to a more or less 1/8 degree set point. This ensures an accurate temperature sensing and readout.
Let me admit, I’m usually skeptical about putting electric equipment directly into water, even if they are meant to be used that way. Because we all know water carries electricity faster and even magnifies it. My high school physics teacher is to be blamed for creating this phobia in me. So, I was worried about using this thing at first.
But nevertheless, I decided to give this heater a shot. I soon realized that my fears were indeed irrational because this thing is certified by the Underwriter’s Laboratories (UL) #1445 for Waterbed Heaters for meeting their safety standards.
The surface coverage of the pad is specially formulated and highly plasticized, which gives it a rugged texture while keeping it and water-resistant. Inside the 64-gauge thermal fused Duraflex black vinyl there is a 32-gauge nickel/copper flexible precision circuitry (w/compensator) that seals the heat shield ensuring your safety.
One thing you do have to make sure is that it’s used in a rigid side box or wooden waterbed frame just for extra precaution.
6. Takagi T-KJr2-IN-NG Indoor Tankless Water Heater
Back to water heaters again. This one here is a tankless water heater, but with a twist. Instead of running on electricity, this one runs on natural gas. It does more than just heat water.
This versatile little appliance can be used for indoor radiant heating. You can say goodbye to your old bulky radiator and the money that it cost you every year for repairing purposes!
The first thing I noticed when I got this is the fact that it’s small and light. And being the curious soul, I opened it up to see what’s inside. I was just stunned by how much room is not being used inside the case too!
It’s a feat of engineering that you are able to get 6+ gallons per min of perfectly hot water from this unit without end. In terms of attaining the title of best hot water heater for hard water, this very one will find quite no competitor.
The tiny and lightweight unit can heat 6 or more GPM of water, no matter how hard it is. It has an energy factor of 0.81-0.83, with inlet, outlet thermostats for constant temperature monitoring.
What’s even more surprising is that this tiny little thing requires no batteries, and even has an Energy Star certification for being energy efficient. No electricity, no batteries, pure natural gas and you’re all warm and cozy. Isn’t that amazing?
When I keep saying tiny, you must be thinking it’s a heavy thing with all the machinery concentrated in a combusted little space and it ought to be heavy. Well, absolutely not! Even though it is small in size, it’s also lightweight. The thing weighs only 37 pounds.
Much less than your ordinary water heater and radiator put together considering it would do the job of both. It not only saves your system from damages caused by hard water, but also saves the space, time, and money you previously had spent behind your water heater and radiator.
One thing that I would recommend is, using flexible water and gas lines with valves for all in and out the piping to make it easier to install. I would also recommend using valves between the Heater Service Valves and the unit so you can easily remove the heater if you ever need to.
7. Calesco Full Watt Hard Side Waterbed Heater
Another good heating pad for your waterbed is the one made by Calesco. Calesco is a trusted brand for heating appliances, and this one is no exception. It’s a hard side and deep filled soft side waterbed heater with 325 watts of capacity, much more than its competitors.
The brand boasts of simplicity. Setting this thing up is super easy. No issues with cord or settings, just one plug and you’re snug!
You don’t even have to drain your waterbed to put it on the bottom of the mattress. The manufacturers believe the lower the magnetic field, the less energy it takes. So, this heater is a saver in terms of energy efficiency. The temperature regulation is around 70 to 100 degrees.
Along with the control panel, heating pad, and power cord, the package includes a small patch kit and a 5 oz Premium Clear bottle of conditioner for free.
8. Rinnai V94iN Natural Gas Tankless Hot Water Heater, 9.8 GPM

Rinnai’s tankless natural gas water heater is one of the best options for hard water. It is easy to install and delivers continuous hot water to your bathroom, laundry, and kitchen – and works best for one application at a time using the flow rate of up to 9.8 GPM. The heater design is quite compact and can fit wherever needed. Since it only heats water when required, you can save a lot of power and utility costs. On-demand heating combined with the tankless version leaves no room or scope for hard water buildups and mineral deposits. This makes your water heater last longer – for up to 20 years! – especially if installed and maintained professionally.
The improved hard water scale prevention also reduces the possibility of pipe and appliance damages. Rinnai V94in is highly recommended for people who have hard water supply in their homes. Regular inspection will help you detect mineral buildup, and you can clean various parts using vinegar based on the product instructions. You will also need to flush out the water heater with vinegar or install a scale inhibitor to ensure durability and optimum performance.
9. iHeat Tankless S-9 240V 39A 9KW Stainless Steel Enclosure 7.2″ by 11″ by 3″ 1/2″CPT 36′ AWG#8 Electric Water Heater, 7.5 lb

This is one of the best water heaters for hard water by iHeat. It has a tankless design and is made of IPX-4 waterproof, stainless steel construction which allows for safe temperature adjustments on the touchpad. The compact appliance is ideal for point-of-use applications and can heat water at home as well as in commercial kitchens and hospitals. With such on-demand heating, you can save up to 60% on utility costs. The heater enables smooth temperature transitions between different water outlets. So, you can have instant hot water in your faucet, shower head, dishwasher, and washing machine – assuming that you use one function at a time.
The electric water heater system also eliminates the need for exhaust pipes and hefty installations. It is easy to set up with professional help and provides great value for individual, small-scale applications – like in studio apartments. Based on heater compatibility and expert advice, you can install hard water cartridges to tackle mineral buildups and keep your heater working efficiently.
10. Chronomite SR-20L/240 HTR 240-Volt 20-Amp SR Series Instant-Flow Low Flow Tankless Water Heater

Chronomite’s tankless electric water heater is best for hard water supplies and operates at a 0.5-GPM flow rate. It is super easy to install and can be hardwired to any limited space due to its compact design. Within a few seconds, you can have a continuous flow of hot water at an optimum temperature that is safe to use. This on-demand heating does not need to store water, so the waiting time is short, and your electricity bills are friendlier than ever! It is a great way to be more efficient about water conservation and electricity consumption. The water heater makes an ideal replacement for your old and rundown heater that suffered a lot of damage from hard water deposits.
The heater works perfectly for a single application at a time, so make sure to avoid running the hot water faucet/shower head when it is your dishwasher’s turn. Regarding preventive measures for water hardness, you do need some professional advice on the best products that can be installed to combat the buildups.
How to Get Rid of Hard Water
You can’t actually get rid of hard water, per say. It’s just something you’d have to make peace with. But what you can do is, take measures that would prevent your water system and your appliances from getting ruined because of the hardness of the water.
Besides using the best water heaters for hard water, I’d take the following measures if I were you.

Remove Hard Water Buildups
To remove hard water stains from your water system, you should start by breaking the system down into individual parts, and take care of the deposit that has developed in each part separately.
For example, if you want to clean the scale buildup in your bathroom faucet, first you need to unscrew the end of the faucet. You’ll notice there is a small removable filter at the end.
All faucets have that, regardless of the brand and model. Remove any rubber gasket (if there is any), then with an old toothbrush, manually give the faucet a good old-fashioned scrub under running water. This should remove all surface deposits.
If there is calcium and rust, heat up some white vinegar just to enough temperature that you can stick your finger in it. Put the faucet in it, and see it works its magic. The liquid will start bubbling, and in no time, you’ll have your faucet shiny again.
This happens because calcium is an alkaline earth metal (meaning it has two valence electrons in its outer shell), it’s highly reactive with acids, like vinegar. And the chemical reactions happen because of the energy the heat produces. It’s no magic, actually, just simple high school chemistry.
Get Rid of Hard Water Stains
The process of getting rid of hard water stains is pretty much the same. Just combine a mixture of one-part vinegar with one-part lukewarm water in a spray bottle and spray on the area you want to clean.
Leave it for 15 minutes or so for the vinegar to work its chemical reaction, then wipe it off with a warm rag or sponge. No need to open up the whole thing.
Use A Water Softener
The last resort in fighting water hardness is a water softener. A water softener is like a magnet that attracts calcium and magnesium in hard water. It’s a negatively charged resin, usually made of compressed salts such as sodium or potassium chloride; to attract the positively charged minerals in the water.
Resins have to undergo periodic regenerations by passing through concentrated brine. These concentrates often contain sodium, potassium, or hydrogen chloride. The calcium and magnesium become bound to the resin, making the water soft.
Best products to extend your hard water heater’s lifespan
As discussed in this article, you can either use a toothbrush to clean parts, soak them in vinegar, or use a water softener to minimize the impact of hard water. Limescale and other buildups in the heater and pipes can affect the functionality of your hard water heating system. This is because the increasing layer of deposits will slow down your heater’s performance and require more energy to heat the same amount of water – which is not efficient at all.
Not only does this increase your waiting time, but it also comprises the energy efficiency of your once smooth-running water heater – and that translates into higher bills. For this reason, it is not enough to just use a tankless alternative. While it does solve the problem of storing hard water in a tank, it does not make your heating system completely mineral-proof. You do want to make sure that your water heater continues to work properly in the long run, and this requires regular maintenance.
Various water heater tools or water softeners are available for installation – like the 3M Aqua Pure scale inhibition system and the anode rod discussed earlier. Here are some other options you can use to make sure that your hard water heater works just as expected. You require professional help for any such installations. You also need to check for heater compatibility before installing the hardware – otherwise, you might find yourself in hot water!
iSpring ED2000 Whole House Water Descaler, Alternative Electronic Salt-Free Hard Water Conditioner, Reduces Limescale Prevent Deposits Build-up

This is a whole-house water descaling system that uses salt-free technology to eliminate hard water buildups from your heater. It does not require chemicals or salt for this job and can easily dissolve existing buildups while preventing new ones from forming. The appliance descales your whole water network, targets mineral deposits in pipes, and improves the performance of your heater. This boosts the energy efficiency of your hard water heating system and is a simple solution to skin/hair problems arising from hard water minerals. The entire descaling technology works on electromagnetic principles to break down stubborn deposits within your heater and connected pipes.
The result is that your water heater will resume its peak performance, deliver hot water quickly, and last longer.
Scalesweeper Water Descaler | Electronic Water Conditioner Installs Where Water Enters Home To Protect Plumbing, Water Heater, Appliances 24/7 | Prevent Hard Water Scale & Scale Buildup

This is another descaling appliance designed to remove hard water scales and deposits. It is made by Scalesweeper – which is a very fitting name! – and features durable construction. Everything from your hard water heater to the connected pipes and end fixtures will be included in this mass descaling protection. Unlike other water softeners, the tool works without salt and chemicals and is a simple yet effective choice for refreshing your water heater parts and connections. It is compatible with various pipe materials including stainless steel, copper, and PVC. The whole system works by allowing minerals to simply flow down the drain instead of sitting idle within pipes and fixtures. This keeps your heater’s heating elements in perfect condition by preventing scale formations that restrict hot water flow.
Trillium Worldwide TWI-5001 Mineral Magnet II

We found this clever mineral magnet from Trillium Worldwide to be a very DIY-friendly accessory for solving hard water issues. If you feel that the intimidating water softener/descaling hardware and anode rods are out of your league, then consider using this mineral magnet instead. It can be installed on pipes and works by using a magnetic field to polarize the mineral salts in hard water. And just like that, scale buildups in your water heating system can be removed. The hard minerals will simply flow through the water without getting a chance to accumulate and solidify. It is the best, non-technical solution for keeping your hard water heater efficient, smooth, and durable for a long time.
Last Few Words Before I Part Ways
As you can see, finding the solution to your “Hard Water” problem is not so “hard” after all. Nowadays, people have access to specific ways to combat this thing and make water safe for use.
One of the ways is to use the best water heater for hard water. Personally, I trust Eco Water Heater for the ease of use and how smooth the controls are. You can always have alternatives in mind. If the products alone don’t combat the phenomenon, you can follow my guidelines in the post.