Is It OK To Use Tap Water To Brew Coffee?


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You might have heard that using tap water isn’t good for brewing coffee. Is that true and what is the best water to use for brewing coffee? 

If the tap water is safe to drink, you can safely brew coffee with it. Any off flavors in water will also be noticeable in the coffee. However, the alkalinity and mineral content also have their impact on taste. Filtered (non RO) or bottled water is the best brew water option for most people. 

There are some other details you should know like the effect of using tap water on your brewing equipment and how water impacts the taste exactly. Keep reading below to find out more. 

Can You Use Tap Water To Brew Coffee?

Is using tap water to brew coffee good or not? Coffee is about 98% water so it’s important that you pick the right source. 

Of course if it’s OK to drink the tap water in your area, it’s fine to brew coffee with it from a health perspective. To brew coffee, usually the water is boiled anyways which gets rid of most microorganisms. However, non-organic pollutants like heavy metals will not be removed by boiling. So if the tap water in your area is not safe to drink, boiling it to brew with doesn’t necessarily make it safe. 

However, the water you use does have a big impact on the taste of your coffee. Sure, the coffee beans are what give coffee it’s taste but the liquid in your cup is still 98% water. So if there is any taste or funk to the water you’re using, it will have quite a big impact on the taste of your coffee. 

Below I’ll go into more detail how water can change the taste but here is a quick rundown of what’s best for you;

  • You are happy with your coffee and your equipment is fine: Use tap water. 
  • You are happy with the taste of your coffee but your equipment is getting clogged: Use filtered (non RO) or bottled water.
  • You think the coffee could improve but don’t want to go overboard: Use filtered (non RO) or bottled water.
  • You want the best coffee possible: Use RO or distilled water in combination with water treatment tablets. 

How Water Impacts Coffee Taste

As said above, coffee is 98% water so any off flavors, smells and funky notes are going to impact the taste of your coffee. When you’ve lived in a place for a while, you might not notice the tastes anymore but there likely is. Just think about when you travel somewhere else. You’ll often taste the water and it’ll be different. (Have you noticed the coffee also tastes different on holiday?) 

However, strange flavors in the water aren’t the only way it impacts the taste of coffee. There are two parts to how perfectly good drinking water can impact the taste of your coffee. There is the alkalinity and the mineral content. 

Coffee is acidic from itself. This can result in a beautiful, juicy fruitiness in. However, if the water you’re using is  alkaline, this buffers the acidity and you end up with a flat tasting coffee that has no acidity but only bitterness. And of course if the water you’re using is already acidic, the coffee can become unpleasantly sour. A Ph level of around 7 (6.5 to 7.5 is acceptable) will result in the best tasting, balanced coffee. Using water that has a Ph level outside if the acceptable range will taste weird. 

The mineral content is another reason. The minerals in water impact how the coffee grounds are extracted. Calcium for example is very important to extracting all the oils from coffee grounds (coffee oils cary a lot of flavor and give body to the coffee). Magnesium and bicarbonate also have their roles to play in proper extraction. On top of that, those minerals do have their own taste as well. 

So if you’re thinking about using distilled water to brew coffee, that’s not going to work either. Having no minerals at all in the brew water will taste weird too. 

Effect on Equipment

Another effect of using tap water for brewing coffee is it’s effect on equipment. If your area has ‘hard’ tap water, it means there are a lot of minerals in it. This has its effect on taste but also on the equipment. 

Hard water leaves more deposits in the lines and brew baskets of your coffee brewers. Especially drip coffee brewers and espresso machines are sensitive to this. That means more maintenance, running more cleaning cycles and possibly a shorter lifespan. 

Is this enough of a reason to use another water source? That’s up to you to decide. It also really depends how hard the water in your area is. If you have an electric kettle you use to boil tap water, take a look inside. Is there a layer of deposits on the inside after a few weeks of use? The same thing is happening inside your coffee maker and the inside of your coffee maker is more difficult to clean. 

If you spent hundreds possibly even thousands of dollars on equipment and quite a bit on high quality beans, it’s not that much of a stretch to spend a little bit more to get the right type of water to produce the best tasting coffee. If you’re using a $25 coffee maker and cheap coffee, using different water still has an impact on the taste but it might not be worth the investment to protect your equipment.

What’s The Best Water To Brew Coffee?

If it’s safe to drink the tap water in your area and are perfectly happy drinking the coffee that you brew with that, there is no reason to change, except for the possible negative effects on your brewing equipment. 

However, if you want to brew better coffee, changing the water is one of those things that feel like it shouldn’t make a difference but it does make a bigger impact than you think. 

The best option for most people is filtered water (not RO filtered) either from your own filter or from bottles. This type of water is usually free of sediments, doesn’t have any off smells and flavors but still has some minerals in it. You don’t want to remove all minerals like a reverse osmosis filter does since that is also detrimental to the taste. 

If you have a RO filter or use distilled water, you need to use some kind of water treatment tablets to get some minerals back into it. Third wave water is one of the companies that makes water treatment tablets to use with distilled or RO water to give it the perfect amount of minerals to bring out the best taste in your coffee. 

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