After the initial ferment, you can choose to drink your water kefir plain OR you can customize it with juice, fruit, herbs and spices. This optional step is known as the ‘second ferment’ and it’s necessary if you want your kefir to be carbonated.

The second fermentation involves transferring the partially fermented water kefir to a new container and adding additional sugars like juice or fruit and sealing it with an airtight lid. Microorganisms present in the water kefir consume the fruit sugars, producing carbon dioxide that builds up and dissolves back into the liquid, resulting in natural carbonation.

If your water kefir still lacks fizz after a second ferment, double check that your bottle/jar has an airtight seal. Without a tight seal, the carbon dioxide will escape, leading to reduced carbonation levels.

Make sure you're using enough sugar (typically 1/4 cup of sugar per quart of water). The beneficial microorganisms in the water kefir grains require sugar to produce carbon dioxide, which creates the fizz. If you're using low-sugar fruits or fruit juice without enough natural sugars, consider supplementing with a small amount of sugar to ensure a sufficient food source for the microorganisms.

Experiment with different fruit juices to find the ones that work best for carbonation. Personally, I've had pretty consistent results whenever I've used pineapple juice. Adding a small piece of candied ginger is also a pretty consistent ticket to fizzy town!

Of course, the fermentation process is also temperature-sensitive. Try doing your second ferment at a slightly warmer temperature, as this can encourage the microorganisms to produce more carbon dioxide. However, avoid excessively high temperatures, as they can lead to over-pressurization and a fizzy mess.

Mold can occur if the fermentation environment becomes contaminated. Mold in water kefir will appear as fuzzy, hairy or powdery growth on the surface of the liquid. It can have various colors, including white, pink, green, blue, black or gray. Harmless Kahm yeast, on the other hand, typically appears as a thin, whitish to cream-colored layer on the surface. It may look wrinkled or bubbly but will not have a fuzzy or hairy appearance like mold.

If you suspect mold in your water kefir, do not consume or attempt to salvage the kefir. Discard the entire batch, clean your equipment thoroughly and start over with fresh kefir grains.

To prevent future mold contamination, make sure that you're maintaining a hygienic fermentation environment. Always use clean utensils and vessels, avoid using chlorinated water and ensure the kefir grains are fully submerged during fermentation.

A creamy-looking white film on the surface of your water kefir is a sign that your brew has captured some wild Kahm yeast. Kahm yeast is typically a thin, whitish-to-cream-colored layer and may appear wrinkled or bubbly. (It will NOT be hairy or fuzzy, which is likely to be mold.) While harmless and not dangerous to consume, Kahm yeast may alter the taste of the water kefir and give it an "off" flavor.

Double check that you're using the correct amount of sugar (typically 1/4 cup of sugar per quart of water). If your water kefir contains too little sugar, there might not be enough food for the beneficial yeast and bacteria, making the environment more favorable for Kahm yeast to take over. 

Higher temperatures can also encourage the growth of wild yeasts, so keep the temperature of your fermenting environment in the 68°F-78°F range. Make sure you're not over-fermenting your water kefir, which can also create favorable conditions for Kahm yeast.

If your kefir has developed Kahm yeast, use a clean spoon or spatula to carefully skim off the yeast from the surface of the water kefir and move on to the secondary fermentation. Kahm is an aerobic yeast, meaning it thrives in the presence of oxygen, so the sealed environment in the secondary fermentation should get the Kahm yeast under control. Fruit or fruit juice in the second ferment can improve the flavor, but depending on the amount of Kahm yeast in the brew, be prepared to discard a batch or two before the kefir's flavor returns to normal.

If your water kefir tastes "off" it might be due to a variety of factors.

An imbalance in the ingredients can lead to the development of wild yeasts (such as Kahm yeast) that may cause unusual flavors. Verify that you're using the correct proportions of water, sugar and water kefir grains in your recipe and that you're not using too much mineral-rich sugar such as sucanat or rapadura. While some minerals are a good thing, over-mineralization can contribute to off-flavors in water kefir, sometimes causing a metallic or bitter taste. (See 'troubleshooting sugar options' below)

Additionally, having an excessive number of water kefir grains relative to the liquid can lead to an imbalance in the microbial population, resulting in undesirable off-flavors. The ideal ratio of water kefir grains to liquid is generally around 1 tablespoon of grains for every 1-2 cups of water.

Higher-than-ideal temperatures may favor the growth of certain microorganisms over others, potentially leading to a shift in the microbial balance within the water kefir grains and changes to the flavor. The recommended range for water kefir fermentation is 68°F to 78°F.

Over-fermentation can also lead to an off-taste. Having too many grains for the amount of liquid and extreme temperatures can both lead to over-fermentation. If your grain-to-water ratio is correct and the temperature is within range, try reducing your fermentation time to see if it improves the flavor.

If you're certain that the culprit isn't mold, sometimes you can salvage an off-tasting batch by moving onto the second ferment stage. The addition of fruit or fruit juice combined with the anaerobic environment of a second ferment can reduce any oxygen-loving wild yeasts that might be contributing to the unpleasant flavor.

It's also not a bad idea to rinse your water kefir grains thoroughly in cool, non-chlorinated water before you use them to start your next fermentation batch.

Healthy water kefir grains should multiply over time. If they're not growing, it could be a sign of stress or inadequate nutrition.

Ensure you are using clean, non-chlorinated water for making water kefir. Chlorine and other chemicals in tap water can harm the kefir grains and inhibit growth. If using tap water, let it sit for 24 hours to allow the chlorine to evaporate.

Verify that you're using the correct amount of sugar (typically 1/4 cup of sugar per quart of water). Kefir grains need sugar as their primary food source. Too little sugar can weaken the grains, affecting their growth. However, more is not always better. Adding sugar beyond the recommended amount can also lead to problems.

Likewise, overcrowding the grains in too little water can also cause stress and they may not multiply as effectively. The ideal ratio of water kefir grains to liquid is generally around 1 tablespoon of grains for every 1-2 cups of water.

Check that the fermentation environment is within the appropriate temperature range (between 68°F to 78°F). Extreme temperatures can stress the kefir grains and impede growth.

Sometimes, the water kefir grains may not be receiving all the necessary nutrients they need to thrive. Refer to 'troubleshooting sugar options' below for a list of ideal (and less-than-ideal) sugar options. You can try adding a small pinch of baking soda or a clean eggshell to the fermentation jar to provide essential minerals.

Healthy water kefir grains should be plump, translucent and have a slightly gelatinous texture. If your water kefir grains are shrinking or deteriorating, it indicates that they may be unhealthy or stressed.

Poor water quality can negatively impact water kefir grains. Make sure you're using clean, filtered water that is free from contaminants and chlorine. If using tap water, let it sit for a few hours to allow any chlorine to dissipate before adding your grains.

Insufficient minerals can lead to grain deterioration. If your water source has low mineral content (e.g. reverse osmosis water), consider adding small amounts of mineral-rich ingredients such as unsulfured molasses, mineral drops or a pinch of natural sea salt to the water kefir solution.

Overcrowding the grains in a small amount of liquid can also cause stress to the grains, affecting their health and vitality. Likewise, ensure that you're using the correct amount of sugar, as insufficient sugar can starve the grains, leading to deterioration. An ideal balance of water kefir grains, sugar and water is generally around 1/4 cup grains + 1/4 cup of sugar + 1 quart of water.

Extreme temperatures can stress the grains. Maintain consistent and appropriate fermentation temperatures between 68°F to 78°F.

Prolonged exposure to direct sunlight can also negatively affect the health of the grains. Direct sunlight can cause the temperature inside the fermentation container to rise higher than the ideal range. UV radiation may also alter the microbial balance in the grains, leading to a decline in their health and fermentation activity. If your fermentation container was in a sunny windowsill, consider moving it to a shaded spot out of direct sunlight.

Healthy water kefir grains are plump, round and have a slightly translucent appearance. The color can vary, but they typically range from off-white to light tan, depending on the type of sugar used as a food source. Color is mostly influenced by what sugar you feed them (brownish sugars = brownish grains). Darker discoloration or brown or black spots may indicate stress or contamination.

Ensure that you are using clean, filtered water free from contaminants and chlorine. If using tap water, let it sit for a few hours to allow any chlorine to dissipate before using. Keep all equipment and utensils used throughout the water kefir-making process clean.

Avoid overfermenting the water kefir. Prolonged fermentation times can stress the grains and result in spottiness or discoloration. Strain the grains from the liquid once the fermentation is complete, usually within 24 to 48 hours.

Make sure you're using the correct amount of sugar in your water kefir recipe (typically 1/4 cup of sugar per quart of water). Too little sugar may starve the grains, while too much sugar can cause stress and imbalances in the fermentation process.

Maintain a consistent and appropriate fermentation temperature. Water kefir grains thrive in a range of temperatures, usually between 68°F to 78°F. Extreme temperatures can stress the grains.

Slight discoloration of water kefir grains is usually harmless and does not necessarily indicate an issue with the grains' health or fermentation performance. As long as the grains demonstrate normal fermentation activity and produce good-quality water kefir, slight discoloration is generally not a cause for concern.

If you prefer to maintain the traditional appearance of water kefir grains or are concerned about discoloration, you can use refined white sugar, which is less likely to cause significant changes in the color of the grains.

If your water kefir is taking an unusually long time to ferment, check the temperature of your fermentation space. Cooler temperatures can slow down the fermentation process. Aim for a moderate temperature range between 68°F to 78°F.

On the other hand, overly-warm temperatures can also cause problems if you end up with Kahm yeast (see 'white film' above), which can compete with the beneficial bacteria and yeast in your water kefir grains, potentially slowing down fermentation and affecting the overall health of the culture.

Ensure you're using fresh, active water kefir grains and non-chlorinated water. Old and/or weakened grains may ferment slower, affecting the overall fermentation process.

If the first fermentation seems sluggish, consider moving on to the second fermentation. Transferring the partially fermented kefir to a sealed container along with some addition sugar or fruit might be the fermentation boost it needs.

If your water kefir turns out too sour, it likely means that the fermentation process has gone on for too long, resulting in excessive production of lactic acid and the strong tart taste that comes along with it. Adjust the fermentation time to achieve the desired level of tartness.

Check the temperature of the fermentation area. Higher temperatures speed up fermentation, while lower temperatures slow it down. Fermenting at a slightly cooler temperature can help prevent excessive sourness.

Using too many grains in a small amount of liquid can also cause rapid fermentation, which can result in an overly sour or alcoholic-tasting water kefir. The ideal ratio of water kefir grains to liquid is generally around 1 tablespoon of grains for every 1-2 cups of water (I aim for 1/4 c of grains per quart).

A second fermentation using sweet fruits or fruit juices can help balance the sourness by introducing natural sweetness and additional complexity to the flavor.

If your water kefir turns out too sweet, it means that the fermentation process has not progressed enough to convert the sugars into acids. The most straightforward solution is to extend the fermentation time a bit longer to allow the kefir grains more time to consume the sugars and produce acids.

Check the temperature of the fermentation area. Lower temperatures slow down fermentation. Fermenting at a slightly warmer temperature can help accelerate the process.

If you've checked these things and your water kefir remains overly sweet after the recommended fermentation time, check the health of your kefir grains. Weak or damaged grains might not ferment efficiently.

If you're using new or rehydrated water kefir grains and they appear otherwise healthy (plump and translucent with have a slightly gelatinous texture), they may simply need some time to adjust and become fully active. Be patient and give them a few fermentation cycles to acclimate to their new environment.

If you've waited for a reasonable period (say, a week or two) and still see little-to-no signs of activity, double-check that you're using the correct ratio of water and sugar and water kefir grains. An imbalanced ratio can hinder fermentation. Aim for 1/4 cup of sugar + 1/4 c water kefir grains + 1 quart of water.

Ensure you're using fresh, non-chlorinated water. If your tap water contains chlorine or chloramine, let it sit out for 24 hours before using it. Alternatively, use filtered or bottled water, as chlorine can harm the kefir grains.