Should I Use Filtered Water For My Kombucha?

If you’ve ever home brewed beer you’ll know that the mineral content and pH of your water plays an important role in the taste of your brew. But is it the same with kombucha?

The common advice within brewing communities is you should always use filtered water. I’m guessing this is the case because this is what is suggested in The Big Book of Kombucha, which is what most people learn from. But is it actually true?

From my experience, there is little difference between using filtered water and tap water. However, there may be exceptions – such as if your water source is particularily hard or soft. Any water source that is particularly hard may change the taste of your kombucha. That being said, if you want to have the purest kombucha possible, filtered water is the way to go.

While using hard water may affect the taste of the brew, will it hurt the bacteria and SCOBY?

Will Tap Water Hurt Kombucha SCOBY?

If there is one thing I’ve learned over the years of brewing is kombucha SCOBY is very resilient. As long as the environment isn’t too hot, too cold, or too dry, the SCOBY will usually be okay.

Some people have guessed that the small amounts of chlorine in the tap water will hurt the bacteria that is needed for fermentation. The fact is, the amount of chlorine in tap water is so small that it isn’t likely to impact your SCOBY.

Kombucha Brewing Myth:

The chlorine in tap water will prevent the bacteria from the SCOBY from developing.

In the US, most jurisdictions require there to be 4 parts per million (ppm) of chlorine in your drinking water. This is to protect against any harmful waterborne bacteria or viruses.

Theoretically, this may reduce the bacteria count in your kombucha. But most of my brewing friends have been using tap water without issue for years. We’ve tried using filtered water and found no real difference in quality.

Do I Need To Boil My Tap Water For Kombucha?

If you’re really concerned about the chlorine in the water you can always treat the water yourself. There are two easy ways to get rid of the chlorine without using chemicals:

  • Boil your water
  • Let your water sit for 24 hours

The chlorine used for tap water is a gas which has been compressed to make it a liquid. At room temperature chlorine is a gas, so if you let your tap water sit overnight, the chlorine will evaporate over time.

The only downside to this method is your water will absorb other gases that may change the pH. This is the reason water that is left out over night tastes a little funny.

As the temperature of the water increases, the solubility of gases changes. The warm water will better absorb carbon dioxide, which will change the pH of the water slightly.

This is why the first method is usually preferred. Boiling your water essentially does the same thing (off-gassing) as letting your water sit over night – it just doesn’t absorb the same amount of chemicals.

If you’re concerned with the chlorine in your tap water just boil your water for 15 minutes before you use it for brewing. This will essentially remove any chance of the chlorine negatively affecting the bacteria in your brew.

Pro Tip:

Boil your tap water for 15 minutes and then let it come to room temperature to remove the chlorine

I should also mention that you must let the water come back down to room temperature before you use it. Kombucha SCOBY does not appreciate a scalding bath of boiling water!

I Have Hard Tap Water, Should I Still Use It?

A lot of home brewers live in rural places where their water comes straight from a well. This usually means the water is usually on the hard end on the spectrum.

For those who don’t know, hard water is water that contains a higher amount of minerals compared to soft water. These minerals are usually calcium and magnesium carbonates.

Here’s how you can tell you have hard water:

  • Calcium build-up in your kettle and in your shower
  • “Scaling” or faint mineral deposits on glassware
  • Your hair feels sticky after a shower
  • It’s difficult for your soap to lather

The World Health Organization states that “there does not appear to be any convincing evidence that water hardness causes adverse health effects in humans.” In fact, some studies have suggested that hard water acts as a supplement for calcium and magnesium.

If you’re unsure about the state of your water you can always purchase a home testing kit to find out for yourself.

If you have extra hard water the taste of your kombucha brew may be affected. However, it won’t negatively impact the life cycle of your SCOBY.

Each water source will be slightly different and each persons tastes will be unique. It is up to your personal taste whether you want use your hard water, or if you want to try using a water softener (some solutions are easier than others.)

There are a few options where you can just purchase a filter for your tap to soften the water. This is the easiest option (and cheapest) if you don’t want to use hard water.

If you’re still worried about the taste and purity of your water (I know a few brewers who are) then you have a few different options for which water you can use.

The Best Water To Use For Kombucha

While tap water is just fine for brewing, it doesn’t mean it’s the best option – just the easiest. If the water where you live is particularly bad you may want to consider other options. For alternative water sources, most people recommend filtered water.

The Pros and Cons Of Using Filtered Water

If you’re going for purity, filtered water is a great choice. You won’t have to worry about chlorine or taste issues. But it does come with some downsides – price and availability.

Pro Tip:

Filtered water is considered ‘best practice’ for home brewing. But don’t be afraid to break the rules!

You’re going to need around a gallon of water for the standard batch brew. If you’re going this route, I’d recommend just buying an “under the sink” filtration system.

These only will cost you around $50-100 and are easy to install. It’s a much more economical option versus buying filtered water bottles.

The other option is to buy a jug with an activated charcoal filtration system in it. These are a little cheaper, but will be more cumbersome to use in the long run.

I’ve also heard people suggest that some of the minerals in unfiltered water may be good for the SCOBY. I’m a little hesitant to believe this claim, but I can see where they’re coming from. People who follow this advice will usually place a mineral tablet back into the water after they’ve filtered it.

Reverse Osmosis and Ionized Water

Reverse osmosis is the most drastic form of water filtration. Instead of removing the minerals and chemicals from the water, the water is ‘sucked’ away from all other substances.

This means you are only left with pure H2O.

As mentioned above, the minerals in water aren’t always a bad thing. They can actually act as mineral supplements to your diet. For this reason, most brewers who use this type of water remineralize it using tablets.

Ionized water uses a similar process as water filtration. A device using electrolysis separates the water into alkaline and acidic components. Some claim that drinking higher pH water leads to various health benefits. However, none have been scientifically proven.

Both ionized and reverse osmosis water come at a high price. As I see no additional benefits over basic filtered water I don’t see a reason to use either.

Using Bottled Water For Kombucha

Similar to filtered water, bottled water may be preferable over tap water for some. However, most people don’t want to spend the money to buy bottled water every time they start a new brew.

If you have a family of 5 and only drink bottled water, it can be costing you up to $3000 a year!

Compare that to the $5 a year once the filtration system is installed and you can quickly see why no one really uses bottled water long term.

If you’re in a pinch, there’s no reason you can’t use bottled water for kombucha.

If it’s between tap water and bottled water, just boil your tap water for 15 minutes and you’ll save yourself a bunch of money.


For most people, tap water is perfectly fine for brewing kombucha. I’ve been using it for years without any negative consequences.

If you’re picky, either buy a water filtration system, or just boil your tap water for 15 minutes before using it. Remember to let it cool back down before letting it touch your SCOBY.

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