Water Guide – Can I Brew Kombucha with Tap Water?

So you want to know if you can make brewery quality kombucha with tap water, huh?

Listen booches, we’re going to let you in on a couple secrets here:

1. Water is equally important as any other ingredient in your brew — perhaps the most important.
2. It’s more than likely every bottle of kombucha you’ve ever purchased started off with “tap” water from the local municipal supply.  

And most other beverages you drink start out the same way. The key is in how that water is processed prior to being bottled.  Are we curious yet, or did we just want the simple answer?

In short, yes you can absolutely make brewery quality kombucha at home with tap water — it’s what professional brewers do every day!  But don’t start your brew just yet, because as is usually the case in life, things usually aren’t that simple.  And while the simplest solution is to use distilled or bottled water, all that plastic (and fuel spent transporting the filled bottles) is not very good for the environment — or your pocketbook.  So if you want to brew like a pro, you’ve got to process your water like a pro.  We’re here to help! 

But first we need to learn a little bit about why the quality of the water you use is so important for your brew.

But first we need to learn a little bit about untreated tap water and why it can be problematic for brewing…

Kombucha & Water Quality

Water quality is important for kombucha production for several reasons, including:

1. pH level:  The pH level of the water is important for kombucha because it affects the growth and metabolism of the bacteria and yeast in the SCOBY. Water that is too acidic or too basic may inhibit the fermentation process, resulting in a weak or flavorless kombucha.  Because different water has different pH, it is important to check your brew’s pH when you start your brew, to make sure it’s starting within a safe and proper range.
2. Chemical contaminants:  The presence of chemical contaminants in the water can be harmful to the SCOBY and the fermentation process. Certain chemicals, such as chlorine and chloramine, are commonly added to tap water to kill bacteria and other pathogens.  However, these chemicals can also kill the beneficial bacteria and yeast in the SCOBY, as well as alter the flavor and carbonation of the kombucha. Therefore, it is important to use water that is free from chemical contaminants, or to use a water filtration system to remove these contaminants.
3. Microbial contaminants:  The presence of microbial contaminants in the water can be harmful to the SCOBY and the fermentation process.  Water that is contaminated with bacteria, fungi, or other microorganisms can introduce unwanted contaminants into the kombucha, leading to spoilage or illness. Therefore, it is important to use water that is free from microbial contaminants, or to use a water filtration system or boiling to kill any potential contaminants.

Next we need to learn a little bit about untreated tap water and why it can be problematic for brewing…

Kombucha and Tap Water

While most of us take it for granted, water is the source of all life on earth — including the life in kombucha.  From collecting untreated water, to treatment plants, to pumps, to underground infrastructure, a lot goes into getting that (kind of) clean water to come out of your tap.  The Romans would be proud of modern water infrastructure, that’s for sure, but they may not be so excited about the chemicals and contaminants that are in the modern water supply.

What’s in my water, you ask?  Here at Raw Brewing Co., we like to put water contaminants things into two categories: contaminants that definitely aren’t good for kombucha, and contaminants that probably aren’t good for you!  Let’s get to it.

Category 1: Contaminants that definitely aren’t good for kombucha

Chlorine, Chloramine and Sanitation By-products: Water picks up nearly any contaminant it can on its way to the processing plant.  This means it has to be cleaned and disinfected before it can be sent out — and it needs to stay disinfected till it comes out of the faucet.  And just like disinfectants kill bad bacteria, viruses, mold, etc. — they also kill the good bugs in your kombucha the same way.  And we’re trying to encourage the good microbial growth, not inhibit it, right?  To maintain a consistent, healthy culture we need the disinfectants out of our brew water.

There’s many chemicals used in drinking water’s disinfection process (like trihalomethanes and haloacetic acids, that may cause cancer and reproductive issues), but we are going to focus on two most common: chlorine and chloramine.

• Chlorine: chlorine is an antiseptic used in municipal water supplies, swimming pools, etc. to disinfect.  While relatively non-toxic to humans, in the long run (over several generations), it will absolutely weaken your culture to the point you’ll need to start with a new scoby.  But don’t fret — it can easily be removed (see below).
• Chloramine: A chlorine alternative that is becoming more prevalent due to its stability and is now used in 35-40% of municipal water supplies (and growing).  Chloramine is made by combining free chlorine with ammonia, creating a more stable compound.  And while not quite as strong as chlorine, it’s stability means it lasts longer in the water and is a little more challenging to remove.   

Pathogens: Bacteria, viruses, and parasites also find their way into municipal drinking water supplies. While these are much better controlled than in Roman times, it still happens around the world everyday.  And while the acidity in kombucha would likely kill any viruses and parasites that may be present, you certainly don’t want any foreign bacteria or yeast getting into your brew that would compete with the good bugs in kombucha.

Category 2: Contaminants that probably aren’t good for you

Fluoride: Fluoride is sometimes added to municipal water to improve public oral health but many believe to be toxic to people.  For kombucha, the fluoride in municipal water supplies does not seem to be toxic — in fact, tea also has fluoride in it.  However, it can certainly be removed if you do not want it in your brew.

Lead and other Heavy Metals: Probably the most famous of the bunch, lead is a heavy metal and can leach into water from lead pipes and plumbing fixtures.  It’s known to cause neurological and behavioral issues in kids, as well as significant adverse health effects in adults.  And what most people don’t realize is even relatively new fixtures can contain significant amounts of lead.  Plenty of other harmful heavy metals like mercury, cadmium, copper, and zinc also frequently enter municipal drinking supplies. 

Atrazine, other pesticides, and nitrates (fertilizers): Atrazine is a hormone-disrupting pesticide, and along with others, it’s detection is quite common in municipal water supplies. Fertilizer run off from farms and agriculture is the culprit here.  And while nitrates occur naturally, they have become a widespread contaminant of municipal water supplies.

Arsenic, Vinyl Chloride, Perchlorate, Petrochemicals : In 2000, the EPA estimated that nearly 15% of Americans drank from water supplies containing arsenic above 3 parts per billion.  Since then, levels of arsenic detected across the country have continued to decline, but it’s still still out there, so it’s still worth mentioning. Vinyl Chloride is used to make PVC pipe, and leached during the water’s journey to homes and businesses, this carcinogenic contaminant has been detected drinking water from a small number of cities across the country. Perchlorate is extremely widely used in rocket fuel, explosives, road flares, etc., this highly toxic chemical can interfere with the thyroid and hormone production (and it has been detected in water in at least 26 states). Finally, chemicals like tricholorobenzene regularly make their way into water supplies.

Pharmaceuticals: Crazy, right?  But prescription drugs make their way into our water when patients go to the bathroom or flush medication down the toilet.  Prescription drugs have been found in nearly every municipal water supply and every part of the ecosystem.  In Florida, 17 prescription drugs were found in a single fish! https://www.bonefishtarpontrust.org/downloads/bonefish-study-summary.pdf

So let’s talk about your options for getting contaminants out of your water…

Chloramine or Chlorine: Which is in your city’s water?

Before discussing options, first we need to figure out which disinfectant is in your city’s water.  It all depends on where you live, but 98% of the US water supply uses either chlorine or chloramine.  However, it’s important to remember that some municipalities can switch between the two because of changes in unprocessed water quality and/or the market cost of the two chemicals.  This information is readily available through your utility’s website or by calling them.

So…you still want to use tap water, huh?  Trust, we get it — here at our brewery (and nearly every other), it’s the only feasible option.  So let’s talk about your options.  1: you can use the tap water right out of the faucet — or 2: you can purify it.   Keep in mind that using water right out of the tap will likely lead to weakening of your culture over time — and you’ll probably need to buy a new scoby a few times a year.  But this is often the easiest thing for some, and booch freaks all over the world successfully use water right out of the tap. 

As to purification, there’s lots of ways to achieve it, but we’re going to keep it to the most common available to the home brewer: boiling, activated carbon filtration (activated charcoal), reverse osmosis filtration, reverse osmosis filtration + UV sterilization. 

Boiling out Chlorine and Microbial Pathogens

Boiling water for 5-10 minutes will remove all the chlorine and kill any pathogens in your water; it is generally the cheapest, easiest option.  However, it’s also time consuming and it will ONLY work for chlorine and microbial pathogens.  Technically speaking you can boil chloramine out of water, but the reality is that by the time you did, you wouldn’t have any water left in the pot either.  So…boiling will NOT work for chloramine (or anything chemical contaminants, really).  But If you’ve got a relatively high quality water supply that uses ONLY CHLORINE as a disinfectant, this could be an acceptable option for you and your booch.

Activated Carbon Filtration (Activated Charcoal)

Carbon filtration is a decent, inexpensive intermediate option.  Like chlorine, chloramine can vastly be removed with carbon filtration; however, not all activated carbon filters can remove chloramine.  For instance, Brita makes no claim to remove chloramine with its filters.  This is because chloramine is relatively stable compared to chlorine — and thus requires a more reactive media (the activated carbon) and a longer contact time to effectively remove.  But hey, using a Brita is certainly better than nothing!

But activated carbon filters will NOT remove microbial contaminants like bacteria, mold spores, and viruses — and it will NOT remove calcium, magnesium, fluoride, nitrates and many other compounds. However, a high quality activated carbon filter can remove organic compounds that affect color, odor, and taste.  It can also reduce pesticides, some petrochemicals, and some pharmaceuticals.

Every water treatment method has limitations, and most commercial beverage operations use a combination of treatment processes to effectively treat water. There are many types of activated carbon and carbon filters — some remove different contaminants, but none removes all types with maximum efficiency.  Not all filters are created equal, so if you choose to go with solely a carbon filter, it’s important to carefully review manufacturer claims to choose the right one.  Most importantly for your brew, does it remove chloramine?

And remember: the use of charcoal water filter can have side effects if your filter becomes inundated with organic contaminants or hasn’t been used in 5+ days.  The filter can become a source of food for bacteria.  And while it may not be harmful to you, it could certainly affect the performance of your brew.  Because of this one reason, we don’t love the idea of using activated carbon filters alone, but it’s certainly a better alternative than plain ole unfiltered tap water.

Reverse Osmosis Filtration

Reverse Osmosis (RO) is high-tech water treatment and generally considered to be the gold standard of water filtration.  This too, is highly affordable for the home brewer, with low-capacity countertop units starting at around $150.  And guess what? RO almost always starts with carbon filtration.  

The difference between RO and carbon filtration is the additional processing step of going through a high-quality reverse osmosis membrane with such small pores only water can get through. Activated carbon filtration is quite effective at reducing or removing contaminants and impurities like chlorine, sediment, organic volatiles, bad taste, and bad odor, whereas RO membranes can remove bacteria, viruses, spores, parasites, heavy metals, fluoride, pesticides, petrochemicals, and almost everything else.  See the chart below for the differences.

RO water is what we (and nearly every other commercial brewery) uses for our brewing.  And as the gold standard, it’s what we recommend for the serious home brewer who wants consistent, brewery quality kombucha, every time.  

Reverse Osmosis Filtration + UV Sterilization

UV light sterilization is an extremely environmentally friendly way to kill bacteria, mold, fungi, and viruses without using any harmful chemicals — it does not produce any corrosive or disinfection by-products.  If RO is the gold standard, RO + UV sterilization is the diamond encrusted version. 

Remember how we said no water filtration system is perfect?  The same goes for reverse osmosis, which filters out about 99.9% of bacteria, viruses, mold, fungi, etc.  RO water is good enough for almost any application, but here at the brewery we take it a step further.  UV sterilization also kills 99.9% of bacteria, viruses, mold, and fungi — bringing us up to 99.9999%.  And it doesn’t get much better than that.  While RO is plenty sufficient for the home brewer, many off-the-shelf systems include UV sterilization as well, and we’re all for it!

There you have it, booches.  Ready, set, brew!