Leaving Water in a Coffee Maker Overnight – Know the Facts

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    In this fast paced world, every one of us want to do each and everything in a quick and swift manner. As an avid coffee drinker, one cannot start a day without consuming a cup of coffee. However, due to time limitations, we are always in a hurry to prepare an amazing cup of coffee in the shortest possible time. That is why some of us have developed a habit of leaving water in a coffee maker overnight. So that in the morning we don’t have to lose time in filling up the coffee maker reservoir for brewing coffee.

    1. leaving water in a coffee maker overnight

    However, is it okay to leave water in a coffee machine overnight without facing any health or coffee maker performance issues? As a short answer, yes you can consume this water without any health hazards, as the risk is very small. However, one should avoid leaving water in a coffee maker for more than 12 hours, as this may cause serious health as well as machine issues. In this detailed article, we will discuss every bit and details about leaving water in a coffee maker for more time.

    Is it Safe to Leave Water in a Coffee Maker Overnight?

    When it comes to coffee making and consuming it, one have to look at different aspects. In terms of leaving water in a coffee machine, there are numerous benefits such as saving time as well as the efforts of filling the reservoir again and again. However, with every advantage, there are always some tradeoffs.

    Every coffee maker is designed in such a way as to provide delicious as well as healthy coffee to its consumer. But the habit of leaving water in coffee reservoir for a longer period of time such as for overnight, not only affects the coffee machine in longer run but is also a bit hazardous to human life. If we talk about its severity on the coffee machine, then the longer water contact can cause mineral deposits as well as affect the mechanism harshly. Every coffee machine is capable to prepare thousands of coffee cups without any effect on its machinery. However, if water is constantly left for a number of hours, the wear and tear are quite inevitable.

    Secondly, the major issue is effects on human health. Most of the coffee maker reservoirs are made of plastics, which though are food grade and BPA free, however, still not one hundred percent health friendly. If water is left for several hours, the water may go stale, causing the growth of bacteria and molds. Later, if coffee is prepared in this water and then consumed regularly in such manner can affect the human health in an adverse manner.

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    Therefore, it is okay and safe to leave water in a coffee maker overnight, may be once or twice in a fortnight. But this should not become a regular habit, as same may cause trouble to both the human health as well as coffee appliance.

    How Long can You Leave Water in a Coffee Maker?

    2. how long can you leave water in a coffee maker

    A cup of coffee is first thing to consume before leaving for office or sometimes even taking breakfast. That’s why we don’t want any delay in coffee making early in the morning. The best thing about coffee makers with reservoirs is that you can fill these up any time before making coffee. For example, you filled the reservoir and then brew half pot, you still have half water left to prepare another half batch of coffee.

    However, some coffee lovers, due to their laziness or a quick brewing, let the water remain in reservoir for whole day or overnight. This habit affects both the health of drinker as well as the coffee machine in an adverse manner due to staleness in water and growth of mold and bacteria. Though, there is no visible change in taste and appearance, however, some really bad microbes are there.

    As a recommended level, it is advised not to let water remain inside a coffee maker for more than 6 to 8 hours. In an extreme case, the water leaving time must not exceed 12+ hours, which is quite hazardous. Therefore, always use any water inside a coffee maker within 6 hours, and if required later, refill the coffee reservoir with another batch of fresh water.

    How Long can You Leave Water in Keurig Reservoir?

    Why specifically we are separating the case of Keurig from other coffee makers? The reason is, as compared to other coffee machines, Keurig has the ability to retain water for a much longer amount of time. Without the water going stale or having any risk of bacteria growth or lime deposits, any Keurig can safely store the water for up to 48 hours.

    As per practical experiences of a number of Keurig users along with different tests, the water retained for up to 2 days inside any Keurig machines is safe to use. However, most of the experts suggest that if it has been more than 12 hours, then even in Keurigs, you should reheat the water before using it. Therefore, though Keurigs has the ability to preserve the water in its natural form for 2-3 days, however, still for a case that has exceeded several hours, the water should be reheated for a safer side.

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    What to Do If You Left Water for too Long in a Coffee Maker?

    If the water inside a coffee maker is sitting for up to 12 hours, then it is safe to use. You can run a brew cycle and enjoy an amazing batch of coffee without any hazards or issues.

    With the passage of time, you can see (not necessarily), some tiny particles, due to the water bacterial build up or from coffee machine. By running a brew cycle for couple of times, you can get rid of any such mold growth. The reason is water is heated up that kills any bacterial growth inside the sitting water. After performing this process, the water is now safe to consume for making coffee.

    However, if the water is there for more than 12 hours, then it is recommended to drain this water and fill the reservoir with a fresh batch. Though this water may be perfectly safe, however, in this health-conscious era, one should not take any risk. So, throw out the sitting water, give a perfect rinse to your coffee reservoir and fill it with fresh water.

    Similarly, in some cases, if the water is sitting for too long in a coffee machine, certain minerals such as lime scale deposits may occur. What you can do is perform complete descaling process to get rid of any such deposits. Some coffee makers, such as certain Keurig models offer a built-in descaling function. But, still if your coffee maker doesn’t have a descaling function, you can manually perform this operation by using vinegar or some other cleaning agents such as lemon or salt.

    How Long Does It Take for Bacteria to Grow in a Coffee Maker?

    For bacterial growth, the warm and moist environment are the perfect breeding grounds. That’s why once you leave water for too long whether in coffee maker or any other similar appliance, the bacterial mold and yeast growth begins. Especially the coffee makers on the inside are dark and damp as well as warm due to frequent brewing/ boiling. Therefore, if you leave water sitting for too long inside any coffee maker, you will see both mold and yeast growing.

    All this is invisible from naked eye, however, based on different researches, the bacterial microbes keep on growing the longer water is sitting inside a coffee reservoir. There is no exact timeline which can ensure that after this time the bacterial growth starts. The reason being different outer as well as inner atmospheres, different coffee makers construction materials and water mineral composition. However, as mentioned before, never let water sit inside a coffee maker for more than 12 hours, to avoid any bacterial as well as other microbes growth.

    Main Problems of Leaving Water in Reservoir Overnight

    3. problems of leaving water in coffee maker

    Some of the main issues that occurs due to water left in coffee reservoir overnight are briefly explained below.

    • Stale Water

    If water is let standing in a confined space, then with passage of time, it becomes stagnant or stale. The stale or stagnant water is also known as motionless or standing water. In terms of coffee reservoir, as the overall space is quite confined and the reservoir is sealed using lid as well, therefore the chances of becoming stale are more. The taste and flavor as well as the pH of this water changes. Such water is not recommended for consumption due to its harmful and hazardous effect on human body.

    • Water/ Machine Contamination

    Most of the coffee maker reservoirs are constructed with plastics. Though almost every coffee machine manufacturer claims these plastics to be of food grade quality and BPA free, however, same is not true for every coffee machine. With passage of time the sitting water chemically reacts with the material of coffee maker. Due to this, the overall composition of water changes. As a result, the water may be contaminated due to mixing of those little particles that may not be visible to naked eye, but obviously exists and are dangerous.

    • Bacteria and Other Microbes

    Stagnant water give rise to the birth of different microorganisms such as bacteria and certain other microbes. Yes, some of the bacteria types are health friendly and help a lot in different digestive processes. However, the bacteria developed in sitting water is quite dangerous. Consuming this left over water once or twice a month may not cause any damage. But if same left over water is constantly consumed regularly, then in the longer run, the human body is prone to get affected severely.

    • Coffee Maker Damage

    As mentioned above, due to long contact of water with reservoir, the chemical reactions may take place inside a reservoir. Due to these reactions, the water may cause a continuous damage to the internal parts of reservoir as well as the brewing process. Most of the people use tap water for coffee making process, which is composed of hundreds of minerals and nutrients. If the water is left standing for several hours, these minerals may be deposited in the form of lime scale and other deposits. Due to such residues, a deep cleansing or descaling of coffee machine is frequently required.

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    Why People Leave Water in Coffee Maker Overnight? – Benefits

    4. benefits of leaving water in coffee maker overnight

    Despite several consequences, some people still prefer to leave water in their coffee makers overnight. This method has some advantages, which are outlined below.

    • Ease and Convenience

    Every coffee drinker loves to take a delicious cup of coffee early in the morning before leaving home. Some people have quite a busy life and they don’t have enough time to fill their reservoir with water and then wait for coffee brewing. Therefore, it is very easy and convenient to fill a coffee maker with water at night. So, the water is readily available in morning inside the reservoir and with push of a button, the coffee is ready.

    • Quick/ Time Saving Operation

    Who likes to wait for couple of minutes to wash a reservoir, then fill it and then further wait for a brewing cycle. When you have already filled a coffee maker’s reservoir with fresh water beforehand, you don’t have to waste your time in running around to fill a coffee maker reservoir. So, with an over-nightly filled coffee reservoir, you will have a quicker and timeless operation without any hassle.

    • Smart Brewing from Any Point

    Some of the best coffee makers are now equipped with smart/ WiFi technology. All these smart coffee makers allow you to give several commands such as start/ stop brewing from a single touch of your smart phone. So, even if you are lying in your bed after waking up, you don’t have to get up and fill a reservoir or wait for brewing. If the coffee maker is already filled with water, then you can perform smart brewing without coming to your kitchen to start brewing operation.

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    Pros and Cons of Leaving Water in a Coffee Machine Overnight

    This quick pros and cons table sums up everything if you leave water in a coffee maker every night.

    Pros
    • Easy and convenient operation early in the morning
    • Quick and time saving method
    • Ability to brew from any point at any time in smart coffee makers
    • No need to fill reservoir again and again
    Cons
    • Water becomes stale and pungent
    • Sitting water can chemically damage the coffee machine
    • Hazard of dangerous bacteria and other microbes
    • Contamination caused by hazardous water

    Leaving Water in Coffee Maker Overnight – FAQs

    Some of the most frequently asked questions related to leaving water inside a coffee maker overnight are answered below.

    What Do I Use to Clean my Coffee Maker Properly?

    A number of different cleaning agents can be utilized to give a normal or deep cleansing to your coffee makers. One of the most famous agent is vinegar, which is widely used for cleaning any type of coffee maker. However, most people don’t like the pungent taste and smell due to vinegar, so there are a number of other alternatives that can be used to clean a coffee maker properly.

    How Regular Should I Clean my Coffee Maker?

    After every usage, it is highly recommended to give a proper rinse to coffee reservoir. In terms of proper deep cleaning, though it depends on usage, however, it is better to perform a thorough cleaning at least once a month.

    What Type of Water Should be Used in Coffee Makers?

    Almost all coffee makers are compatible with filtered as well as tap water. To avoid any health issues, it is advisable to use filtered water. But as coffee makers already perform a high heating operation during brewing, so using tap water is equally good.

    What is meant by Descaling a Coffee Maker?

    With frequent usage of a coffee maker, certain lime scale and other minerals deposits are formed inside a coffee maker. If these deposits are not taken care of at a proper stage, it may result in ruining a coffee maker in the longer run. Therefore, using certain cleaning agents or a built-in function of coffee makers, descaling should be performed to remove any such elements.

    Leaving Water in Coffee Maker Overnight – Conclusion

    For a quick, hassle-free and timeless brewing, everyone wants to fill their coffee makers beforehand at night. However, leaving water in coffee maker overnight also brings certain hazardous causes along with its benefits. This detailed guide provides with complete explanation of pros and cons of whether you should leave water in a coffee maker or not.

    If you ever left water sitting in a coffee maker for several hours or overnight, share your experience in comments.

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    2 thoughts on “Leaving Water in a Coffee Maker Overnight – Know the Facts”

    1. I live in the midwest and we have a lot of issues with water hardness. We gave up on using a Bunn coffee maker because the tank would get a lot of hardness buildup. It was also difficult to clean it as well. We use a Mr. Coffee now but also have used Cuisinart models. They do tend to get deposits quickly and no doubt shorten its life span. Our Cuisinart had a clean LED indicator which came on like every 10 days. I first thought it might be a defect but a replacement did the same thing. Will have to try adding water just before brewing to see if scale deposits are less. Not holding my breath because hardness is hardness and its something we deal with.

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