What is generally considered better for the perfect cup of filtered coffee. Tap water or bottled water?

The water in London, UK is fairly soft but has loads of calcium in it.

Bottled water I have heard has lots of salt in it.

Which is best?

8 Answers 8


Just think that your drink, coffee, is around 97-98% water so you need quality water to make a quality cup of coffee due the following:

  1. Tap water, beside the calcium, will have additional components and too much calcium will give a taste of acidity to the coffee, calcium makes the water harder.
  2. In order to get a fruity taste from your cup of coffee you need to focus on the balance between magnesium and calcium, magnesium will extract flavor from the beans ... now you know why all the coffee shop coffee taste close to each others and is due the source of water is used( all use tap water) makes them high acidity and requires sugar+cream in order to enjoy that cup :(
  3. Sodium does make the coffee taste acidic like the calcium does so you need balanced or spring water to see difference or even distilled water but the coffee will loose drastically from the flavor ... unbalanced.

    At least the bottled water you know has added magnesium for taste and is in a balance with other minerals including calcium(not looking does stay in plastic bottles ... that is a different story and think tap water pipes and source of water/process used to make “safe” for drinking)

Note: I roast the batches of coffee home and in order to feel the right flavor tried distilled water, tap water and spring water; Currently I use only spring water fresh from the ground and filtered so coffee or tea doesn’t require butter, creamer or any other flavors added in order to feel the real taste. Same does come to sodium.Even tea does follow same path when does come to the water .

One more thing, boil the water and check the sediment left to compare the “tap vs bottled”, “tap vs spring”, “spring vs purified/bottled”.

  • So the closest I am going to get to this setup is buying bottled spring water eg Highland Spring Water yeah?
    – user32613
    Mar 7, 2019 at 6:43
  • 1
    this is what I will do if looking to enjoy a cup of coffee ... do not aim for water with "enhanced" PH due the fact all need to be balanced as is in nature :)
    – n1tk
    Mar 7, 2019 at 7:38
  • Pease consider avoiding code formatting except for source code - it has no auto line-break, which means I could just read “One more thing - boi” on my mobile phone.
    – Stephie
    Mar 25, 2019 at 21:06

The water in London is hard enough to nail to the wall in sheets;)
High calcium [& magnesium] content is the very definition of 'hard' water.
It is so bad here it actually forms a strange almost crystalline-looking scum on top of tea or coffee in some of the worst-affected areas.

Check this map from https://www.aquacure.co.uk/knowledge-base/uk-hard-water-map for a general guide to the UK's water hardness.
Light blue is soft, dark blue is hard water.

enter image description here

I grew up in Yorkshire with some of the softest water in the country [which is precisely why in older times it was the centre of the woollen industry - things wash better in soft water, using half the soap], but spent the past 30 years in London. Until I moved here I thought water filters like Brita* were just some affectation for rich people. They're not, they're to stop London water tasting so bad, get rid of the weird scum on your cuppa & prevent your kettle looking like Mother Shipton's cave after two weeks ;)

enter image description here
Image from Yorkshire.com - Mother Shipton's Cave - a popular tourist attraction known for the calcification of objects hung in the dripping water.

With a jug filter, I need to descale my kettle every year or so & my coffee machine never, as it has its own similar filtration built-in.

Bottled water has too many variables. It doesn't quickly indicate hardness, you have to read the small print & extract the relevant information. It's also ridiculously expensive compared to filtration. Drinking bottled water comes from the days before all domestic water was potable & remains only as the above-mentioned affectation. There's nothing vaguely 'unhygienic' about any British water [nor the entire EU for that matter].

So, buy a filter jug [or if you are rich, a tap filtration system] & enjoy your coffee.

*Other makes are available, this is just the most common in the UK, available in every supermarket.


Bottled water is not typically safer than tap water.In fact more than haft of all bottled water comes from the tap.Buying Bottled water is like pouring money down the drain.

  • 2
    Could you please focus on the question: What should the asker use for their coffee and why? Safety was not in the actual question.
    – Stephie
    Mar 7, 2019 at 13:13

I didn't know this till I just read it:

Why Your Bottled Water Contains Four Different Ingredients

Many of the ingredients that are added to bottled water occur naturally in tap water and in our daily diets.

If you like to drink your tap water then I would use it for anything, including making coffe. Where I live in Portland OR, our water comes from the Bull Run Watershed and it's some of the best water I've ever drank. But when I lived in Santa Cruz CA, that water was pretty bad and I would always use "bottled" water for everything except washing.


Reverse osmosis water is the best for making coffee and drinking. It tastes way better than my tap water.

  • Why is this? Could you elaborate? I think you require some minerals that may help extraction. Also, too much hardness is not good for taste.
    – MTSan
    Mar 7, 2019 at 13:13

I would use distilled water. It gets out more impurities.

  • It is known that some ions are needed to increase the extraction. Therefore, you should look for soft water, but not distilled. Could you reason your claim?
    – MTSan
    Mar 22, 2019 at 5:50

We get our tap water from local sources, such as rivers and lakes. This water may contain bacteria, industrial pollutants, agricultural runoff, and heavy metals and minerals leached from the soil. In order to make the water safe to drink, a treatment plant must filter out particulates, disinfect the water to kill microorganisms, and remove any minerals or other chemicals that exceed the standards set by EPA. And yes Generally speaking, thanks to municipal water treatment facilities, the water that comes out of the faucets in our homes is safe to drink. So simply bottled water is best


Bottled water is indeed a solution, but not one that is always the best. For me personally, environmental reasons are important to me. Buying bottled water is pretty wasteful.

There are some other options as well if your tap water is not of the desired quality. For example, you could look into water filters like the jugs from Brita or Peak Water. You can also see what water your local cafe uses and maybe you can get some water from them if they treat their water themselves. Obviously, they might not do that for you for free.

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