It's in the Water! Choosing a Water Source When Making Cultured and Fermented Foods

Many fermented foods make use of water in the culturing process. The water can do a variety of important things:

  • Water is a carrier for trace minerals that are sometimes important in culturing.
  • Sometimes moisture is necessary to the culturing process, and the moisture is provided by water.
  • Bacteria, swimming in water, are able to contact the material being fermented.
  • Water with other ingredients (sugar, tea) can become the liquid that is fermented to make the final product.
  • The material being fermented is protected from oxygen by staying underwater, which prevents the development of pathogenic bacteria or molds.

No matter what you are culturing, it is vitally important that the water you use be clean and free of pathogens or toxins. Beyond that, certain types of cultures have different requirements for water that you should be aware of to get the best results.

Municipal water quality varies around the country, and so does the quality of spring water and well water. Most cultures are pretty forgiving of water quality as long as the water is drinkable.

The water you use for culturing will most likely come from one of four sources:

Well Water. Water that comes from your own well, or a well you share with some neighbors. Some municipalities also get their water from wells. 

If your water is from a municipal well, there is chlorine, and possibly fluoride, in the water, as well as any other treatment chemicals the utility chooses to add. Private wells are required to be tested for microbial contamination at the time the well is installed, but not thereafter. Well owners should test their water annually for microbial contamination and chemical contamination from nitrates/nitrites, arsenic, petroleum byproducts, radon, or pesticides.

Well water is typically high in minerals, which is good for water kefir, not so good for kombucha, and really hard on your laundry. If the water is particularly acid (pH 7.0 or lower), it can cause leaching of metals from plumbing. If well water is discolored or has an odor, there may be an overly high mineral content from ground contamination or from decayed vegetation.

Spring Water. Similar to well water, spring water comes out of the ground and is used close to the source, or bottled for commercial sale. The main difference between spring water and well water is that spring water is collected at the surface of the earth, while well water is collected considerably below the surface. A natural spring is the result of water in an underground source seeping through the ground or rock and bubbling out through the surface. 

Spring water is also typically high in minerals.  

As a result of having been filtered through earth or rock, spring water is usually considered relatively free of contaminants. However, if the ground it’s being filtered through is contaminated, the water itself can be contaminated too. It can also become contaminated in its journey from the spring, through plumbing, to your faucet. Most people do not have springs as a local source of drinking water.
Tap Water. Water that comes from a municipal water source. This could be glacier water, well water, river water, or water collected in a variety of ways.    

Tap water may be hard (contains minerals including calcium and magnesium), or soft (relatively free of minerals). Since hard water leaves deposits on tile and fixtures, and doesn’t do a great job with laundry, many home owners choose to run their water through a water softener that adds salts to remove the “hard” minerals. To find out what is in your tap water, you can check with your water utility and they can provide you with a water quality report.

Tap water is inexpensive and plentiful, and is almost always of a quality good enough to drink and cook with. It can usually be used “as is” for many culturing projects.

Water that is too “hard” can be a problem for some cultures, while water that is too “soft” can require remineralization for some other cultures. Tap water also usually contains chlorine, chloramines, or fluoride that must be removed for some cultures to work well.

Bottled Water. You can buy water in plastic bottles almost anywhere these days. Check the labels: it can be spring water bottled at the source, or water collected from rivers or streams, or even municipal tap water.

Bottled water may have fluoride added to it.

Distilled water is a type of bottled water that has been completely purified and contains no minerals or chemicals of any sort. Water that is sold in fountain machines at supermarkets is usually distilled or purified in other ways, and is free of chlorine, fluoride, minerals, or bacterial contaminants.

Common Contaminants

Water that is not distilled is rarely pure. Aside from the natural minerals and salts you may find in even the cleanest sources, there are usually chemicals of some sort in your water.

Chlorine is added to most municipal water sources to keep pathogenic (bad) bacteria from reaching the consumer. This is generally a good thing, since the water usually passes through a variety of reservoirs, pipes, and other contraptions before it reaches your faucet. Water can contain all sorts of bacteria or organisms that are easily killed by chlorine. Unfortunately, that chlorine can also kill the probiotics that you are trying to work with. Chlorine is reasonably safe to ingest in the quantities present in drinking water, although some people are sensitive to it.

Chloramines are a compound of chlorine and ammonia. They are more stable in water than chlorine, and are used by many municipalities to ensure the safety of drinking water. Water treated with chloramines has little taste or smell, so this is an attractive disinfectant process for public drinking water. Like chlorine, chloramines are considered safe to ingest in drinking-water quantities, although some people are sensitive to them. Also like chlorine, chloramines can be toxic to some probiotics.

Fluoride gets into water in two ways. It can be naturally occurring, as a trace mineral from the water source, or it can be added by the water utility. Fluoride occurs naturally in fresh water at around .01 to .3 parts per million.

The chemical from which fluoride is derived is fluorine, a very common element that bonds easily with practically anything. It’s called fluoride in its bonded form. Sodium fluoride, hexafluorosilicic acid, or hexafluorosilicate are generally used to add fluoride to drinking water, at a concentration of about 1 part per million. There is a tremendous amount of controversy over whether this practice is helpful or harmful. Many municipal water utilities add fluoride to the water. Some do not. Naturally occurring fluoride is rarely a problem in culturing. Added fluoride is generally toxic to young plants, and can also be toxic to certain probiotics.

Chemical Waste can appear in drinking water from a variety of sources. Any chemical waste that is disposed of in drains or on the ground ultimately finds its way into the municipal water supply. Some of it is removed through standard waste treatment, and some shows up in public drinking water. Even well water and spring water can be contaminated if the chemicals are leached into the soil near the water sources.

Common chemical contaminants include fertilizers, animal waste, detergents, industrial solvents, pesticides and herbicides, radon, heavy metals, prescription medication, and even decayed plant matter.

Treatment Methods

If you are getting your water from a faucet, you may or may not need to treat it before using it for culturing. Some probiotics are very sensitive to the type of water you’re using, while other probiotics are very resilient and can use almost any sort of water. However, if your water is not of drinking quality, you will definitely need to treat it before using it for culturing.

Aeration is a suitable treatment method if all you want to do is eliminate chlorine from the water. Chlorine is very unstable in water, and if you boil the water or put it in a blender for about 20 minutes, the chlorine will percolate out. Or, you can leave water to stand for 24 hours to accomplish the same thing. Aeration will not remove chloramines.

Boiling will take care of most common pathogens that might get into drinking water supplies. It does not eliminate fluoride, chloramines, or other heavy metals or chemicals.

Simple Charcoal Filtration is what you get with a standard countertop or faucet filter system. Charcoal is made of carbon, which bonds with organic materials to remove them from the water it is filtering. Activated charcoal is charcoal that has been processed to open up many tiny pores in the material making more surface area available. Filtering water through activated charcoal is one of the easiest and least expensive ways to remove common contaminants such as bacteria, chlorine, chloramines, etc. Charcoal filtration does not eliminate fluoride.

Enhanced Filtration can be achieved with some types of whole-house filters, or more expensive faucet filters. It usually includes basic activated-charcoal filtration, as well as some chemical or barrier filtration. Enhanced filters will remove some particles that activated charcoal doesn’t trap, such as sediment, calcium, etc. Some enhanced filtration systems are designed to remove fluoride as well, but may require more frequent filter changes due to trapped fluoride.

Reverse Osmosis requires an RO system that may fit under your sink, or may require a separate installation. Reverse osmosis is basically a process of forcing water through a membrane, which removes all particles that are larger than water molecules, but allows the passage of tinier particles. RO systems usually include pre-filters that remove things like chlorine and bacteria from the water before it passes through the RO membrane. RO systems remove most minerals from the water, and will remove most fluoride.

Structured Water / pH-Balanced Water / Ionized Water. Water that has been treated to alkalinize it or to change its structure is not suitable for culturing. Culturing involves a precise interaction of bacteria and the food being cultured. If water is part of that culturing process, the natural structure and balance of the water should not be altered. If your water treatment unit has a setting for "clean water" that does not change the pH and does not alter the water structure, but merely filters out contaminants, then the water can be used for culturing.

What Kind of Water Do You Need?

There are two cultures that have very specific requirements for water: kombucha and water kefir.

Chlorine, chloramines, or fluoride will weaken or even kill either of these cultures, so the water you use must be free of those minerals.

Kombucha will culture best in water that is as pure as possible: even distilled or purified water is fine. The kombucha will get its nutrients from the sugar and the tea that you add to the brewing solution. While kombucha may brew successfully in water with minerals in it, it’s possible that excessive metal content may weaken the scoby.

Water kefir grains require some mineral content to culture successfully and to grow well. Mineral-rich water, such as from wells or springs, is ideal for brewing water kefir. If the water you have available is low in minerals, or if you have to filter it to remove chlorine and fluoride, you can add minerals back to the water in a number of ways.

  • Use a less refined sugar, such as Sucanat or rapadura.
  • Add 1/2 to 1 teaspoon of unsulphured blackstrap molasses to a quart of solution.
  • Add a liquid mineral solution, such as ConcenTrace, to the brew. Use anywhere from 5 to 20 drops per quart.
  • Add about 1/8 teaspoon of sea salt to a quart of brewing solution.
  • Add about 1/4 teaspoon of baking soda to a quart of brew.
  • Put some dried fruit (unsulphured) into the brew: raisins, dates, apricots, figs, etc.

Most cultures, such as sourdough, cheese, and fermented vegetables, are pretty resilient, and will safely use any water that is suitable for drinking. The water can be rich in minerals, or completely pure. Many people prefer to use water that is free of chlorine and fluoride, and there is no harm in removing those things from the water before you culture.

Kitchen Water Facet

Related Articles & Recipes:


Related Products:

Water Kefir Grains
Water Kefir Grains
Kombucha Tea Starter Culture Kombucha Tea Starter Culture
Sourdough Starter Sourdough Starter


Free eBook Library Access & Weekly Newsletter

Sign up today for free access to our entire library of easy to follow eBooks on creating cultured foods at home, including Lacto-Fermentation, Kombucha, Kefir, Yogurt, Sourdough, and Cheesemaking.
  • Library of eBooks for making your own cultured foods
  • Weekly newsletter filled with tips & tricks
  • Expert advice articles, recipes, and how-to videos
  • Join 150,000+ other health-conscious readers
  • We never share your information!
first name last name email address