Does Boiling Hard Water Make It Soft?

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Boiling water can kill or remove several impurities in drinking water. But can boiling hard water make it soft?

We’ve discussed the answer to this question in the below guide.

📌 Key Takeaways:

  • No, you can’t make water soft by boiling it.
  • When you boil water, it removes temporary hardness, but it can’t remove permanent hardness.
  • A water softener is the best solution to remove both temporary and permanent hardness, producing soft water and protecting your plumbing from limescale damage.

♨️ Can You Soften Water By Boiling It?

No, you can’t soften water in a traditional sense by boiling it.

Boiling water will remove temporary hardness – that’s hardness caused by magnesium and calcium carbonate. These forms of minerals precipitate when heated, which means they can be removed by boiling water.

You might have seen white flakes in your kettle or coffee pot after using it to boil water, leading you to assume that boiling your water can indeed soften it. However, these are just forms of magnesium and calcium carbonate, temporary hardness that can be removed by boiling.

The boiling process won’t remove permanent hardness – hardness caused by calcium and magnesium sulfates and chlorides. These minerals don’t precipitate when they’re heated, and another method must be used to remove them from water.

So, in short, boiling your water may soften it somewhat, but it’s unlikely to completely soften it. Most water supplies have both temporary and permanent hardness, so if you want to produce soft water in the literal sense, you’ll need a more comprehensive method of water treatment.

Boiling hard water

🤔 What’s The Difference Between Temporary And Permanent Hardness?

To understand more about temporary hardness and how it is removed by bringing water to a boil, let’s look in detail at the difference between temporary and permanent hardness.

Temporary hardness is defined by the presence of bicarbonates of calcium and magnesium, i.e. Ca(HCO3)2 and Mg(HCO3)2.

Permanent hardness is characterized by the presence of the chlorides and sulfates of calcium and magnesium (CaCl2, CaSO4, MgCl2, and MgSO4).

Temporary hardness is so-called because it can be removed by simply boiling the water source. Permanent hardness is retained in water even when it’s boiled, and can only be removed with water softening.

In most homes, temporary hardness is more predominant than permanent hardness. That’s good news for you – it means you can remove much of your water hardness by boiling it. With that said, most household water supplies still have a mix of temporary and permanent hardness, so boiling water alone is rarely a complete water softening solution.

⚗️ Does Boiling Hard Water Reduce Or Increase Hardness?

We’ve mentioned already that boiling your water will remove temporary hardness, so you might assume that your water will be softer as a result of boiling.

However, exposure to heat also causes pure water to evaporate, meaning that there’s the same concentration of permanent hardness minerals in a smaller amount of water.

We couldn’t find any official sources that claimed boiling hard water could reduce or decrease hardness based on this phenomena. From what we can tell, boiling your water will still make it slightly softer because the small loss of water molecules won’t balance out the precipitation of temporary hardness minerals.

Water hardness test strips

📖 How To Remove Temporary Hardness By Boiling

To remove temporary hardness by boiling your water, follow these steps:

  1. Bring the water to a boil and leave it for a few minutes.
  2. Wait for the water to cool. You should notice white flecks of minerals at the bottom of the pot.
  3. Scoop the water out of the top of the pot, leaving the mineral flakes behind.

You could sieve the water to get more water from the pot without the temporary hardness minerals. However, the white flecks are very delicate and could easily crumble into tiny pieces, possibly recontaminating your water supply, so keep this in mind when using this method of collection.

🔎 Does Boiling Hard Water Cause It To Temporarily Soften?

We’ve seen a few sources saying that boiling hard water temporarily softens it because it increases the solubility of calcium and magnesium salts. We think this information was possibly first shared by somebody who misunderstood the terms “temporary hardness” and “permanent hardness” and has been since spread around by other sources.

We always fact-check our sources before we share anything online and we only take information from authoritative educational institution websites or governmental websites.

We couldn’t find any legitimate evidence to suggest that boiling hard water causes it to be temporarily softened. There’s a difference between boiling hard water to soften it temporarily (which is incorrect)and boiling hard water to remove temporary hardness (which is correct).

⏱ How Long Should You Boil Water To Remove Temporary Hardness?

You should boil water for at least two minutes to remove temporary hardness. The time it takes to boil a kettle is enough to cause magnesium and calcium carbonate to precipitate.

Soft water from boiling

🧐 Is It Worth Boiling Hard Water To Soften It?

In our opinion, it’s not usually worth boiling hard water to soften it, for a couple of reasons.

First, boiling your hard water won’t completely soften it anyway. Even if you manage to remove the temporary hardness, it will still contain dissolved minerals in the form of permanent hardness.

Second, there’s not much point in boiling your water after it has traveled through your home’s plumbing system and out of a faucet. Since dissolved calcium and magnesium minerals aren’t dangerous to drink (in fact, they’re good for our health), there’s nothing to gain from removing them from your drinking water.

Most people want to prevent the effects of hard water in their plumbing pipes, appliances, and fixtures – and there’s no way to achieve that by boiling your water once it has reached the end of its journey.

Of course, if you just want to enjoy slightly softer water for a specific purpose, such as to use in your bath, then boiling it might be enough for your intended use.

💯 Best Method To Soften Water: Use A Water Softener

It would be great if boiling water would allow you to soften water naturally. However, as we’ve shared above, there are limitations to this method, and it doesn’t compare to water softening.

A whole house water softener is the best solution to eliminate water’s calcium content and soften water by addressing both temporary and permanent hardness.

Softening water involves exchanging calcium and magnesium ions with sodium or potassium chloride ions, which are unable to form mineral buildup and scale, in a process called ion exchange.

Water softeners are installed at the main water pipe into your home, meaning that your hot and cold water is softened. You don’t need to boil water to remove temporary hardness once it leaves your faucet, because all the magnesium and calcium ions have already been removed.

Installing water softener home prevents permanent hard water

📑 Final Word

Boiling your water is a quick and cheap way to remove calcium and magnesium ions in their bicarbonate (temporary) form. But it won’t produce 100% soft water, and there’s little point in boiling your water once it has already traveled through your plumbing and water fixtures.

A water softening system is still our top recommendation for producing softened water that’s supplied to your whole household. You can learn more about these systems in our ultimate guide to water softeners.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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