Why Do You Use Cold Water in a Coffee Maker? (Tips)

I’ve always used cold water when brewing coffee, for me it’s one of those things that just goes without saying. But why do we do this?

Fresh cold water is oxygen-rich, and used in your coffee machine this equates to coffee with more flavor. That’s why using chilled filtered tap water is the ideal option when brewing coffee in a coffee maker.

Let’s dive down into the subject of using cold water to make coffee in more detail, and discover why this is best for you, your machine – and the taste of your coffee…

Why Should I Use Cold Water in My Coffee Maker?

If you’re making fresh coffee, you really need to use fresh water and that means cold. Even though the water will soon be brought to a boiling (or near-boiling) temperature in the coffee machine, fresh cold water is rich in oxygen, and this actually helps the flavor of the coffee.

Warm water from the tap is prone to bacteria, so isn’t the best choice when it comes to making drinks. You could add fresh tap water that’s already boiled to your coffee maker; however, speeding up the process can rob the coffee of some of its flavor. 

For the best possible cup of coffee, you need freshly ground beans and cold water, either straight from the tap, filter jug, or bottle (we’ll look more closely at sources of water for coffee machines a little later on).

Does Using Cold Water Make Coffee Taste Better?

Every barista will tell you that fresh water is super-important for great-tasting coffee. If you’re using a coffee maker, always start with cold water. 

Cold water has more oxygen and minerals in it, both of which help to give your brew that lovely, fresh feeling, which will last even when the water’s been heated. Besides, the whole way your coffee maker has been designed involves the machine heating up the water itself: don’t confuse it.

(If you like to know how stuff works, here’s a look at the inside of a coffee maker. This should give you an insight into what can, can’t, and really shouldn’t go into a coffee machine.)

Is It Ok to Leave Water in a Coffee Maker Overnight?

Bacteria love a warm, damp environment, so your coffee maker is an ideal place for germs to grow. Any remaining wet coffee grounds will be an added bonus for bacteria.

So, in general, it’s best to empty your coffee maker’s water reservoir when you’ve finished with it, then fill it with fresh water when you need it again.

However, it feels good to come downstairs in the morning and simply hit the switch on the coffee maker. After all, many of us can’t function until we’ve had that first cup! Can you leave water in the coffee machine reservoir overnight?

We reckon that it’s fine to prep your coffee maker the night before from time to time (maybe for a Sunday morning treat?). A good clean once a week should keep on top of any nasty bacterial growth, and you may also need to descale your machine to prevent deposits building up.

Can We Use Milk Instead of Water in a Coffee Maker?

Please don’t. Coffee machines are designed to heat water to the optimum temperature for water, which isn’t the same as it is for milk. You’ll end up with a really nasty-tasting drink, as well as a machine clogged with milk solids that will be hard work to clean.

Make your coffee in the machine using water, then add the milk later. If you like the kind of milky coffee your grandma used to make, gently warm the milk in a pan then add a shot of coffee. 

If you’re a big latte or cortado fan, you’re better off investing in a machine that will steam or froth the milk for you – and is designed for that job.

How Often Should I Change the Water in My Coffee Machine?

Change the water every time you use the coffee machine. As well as keeping things hygienic, this is how you’ll get the cleanest, freshest-tasting cup of coffee.

The thing we all forget is that over 90% of our favorite drink is made up from water. We wouldn’t make up the cup using stale coffee grounds, so why do we even consider using stale water? Stale has a flavor, whether that comes from the beans or the water.

What Water is Best for My Coffee Maker? (Distilled or Tap?)

We’ve already decided that cold water is better for your coffee maker than warm or ready-boiled water. But what’s the best source for that water: distilled or tap?

Distilled water has a big advantage over tap. There are a lot of minerals in water. Distilling your tap water removes things like calcium and magnesium, which can cause scale deposits to build up in your coffee maker.

However, some coffee aficionados argue that by losing these minerals, you’re compromising the flavor of the finished drink.

Of course, there’s always a middle way: have you tried using filtered tap water for your coffee? You can easily buy carbon filters to filter tap water at home, or perhaps your refrigerator has a mains-fed faucet with a built-in filter.

This gives you constant access to fresh, clean-tasting water, without the effort of having to buy distilled water. You’ll need to change the filters regularly to keep the water fresh: check the manufacturer’s guidelines to find out how often. 

Of course, if you’re good with the taste of tap water, this is the easiest and cheapest way to make coffee, provided you descale the machine regularly.

Not descaled a coffee maker before? This short film shows you how to descale a Keurig coffee maker, using that store cupboard staple, vinegar. Manufacturers like Keurig also sell their own descaling solutions, which can make cleaning your coffee maker super easy.

Can You Use Bottled Water in a Coffee Maker?

There’s a lot of debate around this one. You can use bottled water, yes; however it may have a higher mineral content than your tap water, so will cause even more scaling. Again, using tap water and filtering it yourself gives you the perfect compromise.

We’d suggest experimenting to see which taste you prefer. Tap, distilled, filtered and bottled water will all give you subtly different flavors. This could be so subtle that you won’t even notice the difference!

As long as you keep the machine clean and follow the manufacturer’s instructions, you can try using all different types of cold water in your coffee machine.

Final Words on Using Cold Water To Brew Coffee

So this is all pretty unequivocal – if you want great-tasting coffee from your machine (or brewed any other way), then you must use fresh cold water to make it.

And the best option at home is to use chilled, filtered tap water in your coffee maker.

So that sounds like a plan then. I love it when things are straightforward! 🙂