Distillation and reverse osmosis systems are the only water purification systems that can remove the minerals found in water. Minerals, such as calcium, potassium and zinc, are removed when water is evaporated during distillation or when pushed through a semi permeable membrane during reverse osmosis.
Minerals occur naturally in the water that we drink, and most are beneficial to our health. Unfortunately, some water purification systems can remove these minerals from our water.
Keep reading to learn about not only which minerals are in our water and how they are removed, but also which water filtration and purification systems won’t remove them. I have also explained if we can (or should) add minerals to our water.
Do water purifiers remove minerals?
Surprisingly, there are only two types of water filtration or purification systems that are able to remove minerals from water, these are:
- Distillation
- Reverse Osmosis
1. Distillation
A standard distillation system purifies water by heating and evaporating the water, before cooling the water vapor and capturing it for you to drink. This process removes both contaminants and minerals by leaving them behind during evaporation. This treatment process is indiscriminate and removes nasty things like bacteria and heavy metals, as well as good things like minerals.
Distillation works because the water molecules evaporate at a lower temperature than the minerals in our water. Water evaporates (boils) at 212°F, but mineral ions like calcium, magnesium and even sodium chloride (salt) evaporate at far higher temperatures. For example calcium evaporates at 1494°F, magnesium at 1,994°F and salt at 2,669°F.
So, while distillation does a great job of removing contaminants from the water we drink, it also removes beneficial minerals.
2. Reverse Osmosis
Reverse osmosis systems are able to remove minerals from our tap water because of the semi permeable membrane, and not because of its other filters. So, it doesn’t matter if you have a 1, 2, 3, 4, 5 or even 6 stage system, as it is the semi permeable membrane that is important, and indeed is the primary component of all reverse osmosis systems.
Pressure is applied from the side of the untreated water and the water is pushed through the membrane. As the water flows through the membrane, mineral ions are left behind. This is because mineral ions are larger than water molecules, and the tiny holes of a semi permeable membrane are made to allow water molecules through and little else.
So, much like distillation, reverse osmosis removes both the unwanted contaminants but also the beneficial minerals from our tap water.
Also remember that most semi permeable membranes need replacing every 1-2 years. So, it is a good idea to check how often your particular membrane should be replaced and keep a good cleaning and maintenance schedule to ensure your reverse osmosis system is purifying your water effectively.
These water filtration and purification systems DO NOT remove minerals from water:
- Activated or catalytic carbon filters
- Faucet-mounted filters
- Gravity based filters
- Ultrafiltration systems
- UltraViolet water purification systems
Community and public water systems do a great job of removing contaminants and ensuring minerals are at, or below the advised limits. So it is good to be aware that if you are using a distillation or reverse osmosis water purification system, you won’t be getting the minerals from your drinking water to help you meet your daily recommended intakes.
Are minerals in tap water good for you?
Minerals in our tap water are good for us! There are essential and non-essential minerals that we need for our health. In fact, the Department of Human and Health Services through the Food and Nutrition Board, has established guidelines to help us meet our nutritional requirements.
This includes establishing recommended dietary intakes for minerals, including:
- Calcium
- Copper
- Iron
- Manganese
- Potassium
- Sodium
- Zinc
Thankfully these minerals are often found in tap water.
It is also true that some minerals can be harmful to our health – this is typically when we are exposed to them at high concentrations. The EPA set Maximum Contaminant Levels for anything that might be harmful, and our water systems make sure that any minerals (or contaminants) stay below these levels.
So, we can be sure that the minerals in the water coming out of our faucets are definitely good to drink!
Minerals found in tap water
Minerals enter our water supply from the natural erosion of rocks. The water flowing over these rocks picks up the dissolved minerals – in fact it is often water that erodes the rock in the first place. Therefore, the mineral content of our tap water depends on the minerals in our water supply – so the mineral content varies from place to place, and state to state.
The most common minerals found in tap water though are:
- Bicarbonate
- Bromide
- Calcium
- Chloride
- Copper
- Fluoride
- Iodide
- Iron
- Magnesium
- Manganese
- Nitrate
- Phosphorus
- Potassium
- Sulfate
- Sodium
- Zinc
Calcium, magnesium and sodium are the most common of all minerals found in our tap water.
Typically, drinking tap water won’t even result in you meeting your dietary recommended intakes of minerals, they just aren’t in water in high enough concentrations. In fact, the EPA sets the limits on 90 things that can be found in water – and our water systems ensure that everything stays below these limits. This includes things like fluoride, chloride and nitrates.
Can you add minerals to water?
Minerals occur naturally in our water, although some water purification techniques, such as reverse osmosis or distillation, remove them. Some bottled water can even be high in mineral content (this is called ‘mineral water’), but when it comes to bottled water the FDA says…
“…minerals and trace elements must come from the source of the underground water. They cannot be added later”.
united states Food and drug administration
So, what does that mean for your tap water? Well, there are such things as mineral drops. You can buy small bottles of mineral drops to add to your water.
They are often designated GRAS (Generally Regarded As Safe) by the FDA – but be aware, many of these products are ‘self-affirmed’ GRAS, which means the manufacturer conducted the research for their own product to get the designation from the FDA.
Water Purification has more information on the different ways you can add minerals back into your water available here.
Something else to consider is what the mineral content is in the water you are drinking. Is the water naturally low in minerals? Or, perhaps you use a reverse osmosis system and are considering putting some minerals back in?
If it is just normal tap water, maybe consider getting your water tested first – to make sure you don’t end up with any minerals in high concentrations.
For example, if your water already has magnesium in it and you add more (by adding the mineral drops), you can end up having too much magnesium – which has a laxative effect! Not pleasant at all.
How to remove calcium from water
A high amount of calcium in water is also known as ‘hard water’. Most of the U.S. has ‘hard’ to ‘very hard’ water. This is because the groundwater, where most of our water supply comes from, is in contact with old limestone. The limestone leaches the calcium into our water and while water systems disinfect and treat our drinking water, they do not remove minerals, such as calcium.
Cation exchange water softeners can remove minerals, including the calcium (and magnesium) ions found in hard water. The water softeners work by exchanging the calcium and magnesium other minerals such as sodium or potassium.
If you are going to use a water softener, make sure it is certified by the National Sanitation Foundation. Cation exchange softeners should have certification NSF 44 – that way you can be sure they will work correctly and safely to remove the calcium from your drinking water
Once all the calcium (and magnesium) ions are fully exchanged, the water softener needs to regenerate. The regeneration process uses vast amount of water to flush the system of all of the mineral ions that it picked up. The water softener is then recharged with new sodium (or potassium) ions so that it can be used again.
Related Questions
How do you remove chlorine from tap water?
Activated carbon and catalytic carbon filters are able to remove chlorine from water. Chlorine is trapped in the tiny pore spaces of the activated or catalytic carbon, and the de-chlorinated water is able to flow through.
Does tap water have more minerals than bottled water?
Tap water has a higher mineral content than some bottled water, such as spring or purified water. However, bottled ‘mineral water’ has the greatest mineral content, much higher than that of tap water or other types of bottled water.
Although, it is possible for tap water to have a greater mineral content than mineral water, but this only occurs in specific geographic locations that have naturally high mineral content in their water supply.
