Do you reserve water in your coffee maker so you can wake up and immediately make coffee? Have you ever wondered if this is healthy? Research suggests that leaving your water for a long time in a coffee maker is not a healthy practice. It reduces the flavors and freshness of coffee made with it as well. So, how long can you leave water in a coffee maker?
You can leave water in the coffee maker for no more than 4 days. If you keep water for a longer time, water becomes stale, contaminated, and unhealthy. Try changing water every 2-3 days and clean the coffee maker regularly.
But there’s more to know about how long you can leave water in the coffee maker. In this article, we’ll go into detail as to why you don’t want to leave water in a coffee maker too long.
Let’s get started.
Why Should You Leave Water in a Coffee Maker?

Do you often leave water in the coffee machine at night? If yes, you are not alone, dear. The majority of coffee maker users pour water overnight to consume an instant cup of coffee in the morning. Here are some good things I love about leaving water in the coffee maker;
1) Save Valuable Time
Author Note: Remember the morning rush? When you leave water in the coffee maker, it can save your valuable time. Wake up, do your rituals properly with the happiness in mind that your coffee is just one tip away! A smooth, hassle-free morning can make your whole day better.
Or, ever faced the last minute hastiness for sudden trip preparation? A surprise visit of friends at your place? Pre-loaded water in the machine will be a relief.
During office time, you can give much concentration to your official task rather than coffee preparation.
2) Grow Ease of Your Work
The typical coffee makers are easily portable to anywhere, anytime. You don’t need to go for many complexities. Just press on the pre-programmed button on the coffee machine and now get the test of a freshly brewed hot cup of coffee in only 2 minutes without any physical mixture of sugar, milk, and coffee powder.
The coffee makers are finely designed with an automatic button consistent with different glass and cup size. When you press the button, you can get your desired cup of coffee because of the integrated artificial intelligence. So you don’t need to pour and heat water on and on.
Why should you not leave water in a coffee maker?
If you love coffee, you would know how beneficial and handy the coffee brewer is. But when you routinely leave water in the machine for an extended period, you may face some difficulties.
1) Coffee Will Lose its Freshness
Storing water in your coffee brewer reservoir for a long time may tend to cause your water to be moldy.
Carbon-di-oxide is the main parameter to decline the pure pH level of water, resulting in loss of taste. Generally, the pH of water gradually decreases when it comes in contact with air.
Likewise, when water is kept for several hours overnight, the water of the coffee machine’s reservoir becomes stale due to an inner chemical reaction.
If you are not that much serious about how your coffee tastes, you are good to go. But otherwise, I believe it’s worth investing a few moments in pouring some freshwater for a delicate coffee with a perfect smell.
2) Water Clogging Facilitates Bacteria Breeding
Lab tests executed in CBS stations in Chicago, Dallas, and Pittsburgh have detected some harmful bacteria, like e-Coli, klebsiella staphylococcus, pseudomonas aeruginosa, streptococcus, etc., in coffee machines.
Leaving water in a stagnant state in a reservoir, bacteria, and fungus can quickly grow in a perfect environment. Although some machines have special features, bacterial growth can also be detected on account of temperature changes.
A research report from Spain’s University of Valencia suggests that 35-67 types of bacterial species can breed on each coffee maker’s drip tray and easily make you diseased.
However, the water reservoirs of most good coffee makers are roofed with leads that defend its surrounding from outer germs and insects.
3) Mineral Lays Down in the Water Tank
Using filtered water is the best choice to leave in a coffee machine rather than tap water. Because tap water contains a high concentration of minerals that may lead to damaging your machine due to its residual deposit.
”High total hardness will increase the weak acids in the cup, and high carbonate hardness leads to the huge crust when cupping but also means more frequent descaling for the coffee equipment.”
Limescale is the primary indicator that determines coffee brewer life expectancy. Calcium is a basic component of Limescale. Water containing calcium may pile up on pipes and clogs in machine pumps while at rest for days. Consequently, it will prevent you from running your machine properly.
So, Should You Leave Water in a Coffee Maker?

You can sometimes leave water in the coffee maker for use within a limited period.
Author Note: It will help you get some quick sip of warm coffee within a minute. You don’t have to waste time putting water in the machine. Just be sure not to leave for more than the recommended time because it alters the taste and quality of water. Sometimes water smells bad for the growth of bacteria.
According to one survey, “In fact, 50% of these household machines contain yeast and mold.”
High levels of bacteria can cause sickness to our bodies.
Besides, water makes the metal of your machine rusty. So, don’t put water in coffee makers for weeks or months unnecessarily for keeping your machine operative for a more extended period.
How Long Can You Leave Water in a Coffee Maker?
You can preserve water in a coffee maker reservoir for 3-4 days because old water holds bacterial and fungal growth risk. It can be quickly grown in a warm and damp environment.
But, the good news is, most bacteria vanishes at 75 degrees Celsius. For this, filtered water being heated is the best solution to keep safe from bacteria.
There are various sizes of coffee makers available in the market with different brew sizes. If it is small, such as having less than 6 cup brew size, you can completely pour water in the coffee maker. And replace the water if not used within 3-4 days.
If the machine has a larger tank with 12 cups or more than 12 cups of brewing capacity, you won’t need to refill it after brewing each coffee cup. At the same time, reserve your water according to your daily needs.
Keeping water for a longer time reduces the longevity of the machine. When you use the coffee brewer machine regularly, it’s not difficult to deal with the coffee machine’s correct maintenance. Using the machine appropriately will determine whether the machine works for some years or not.
It would be best if you cleaned the water tank at least once a month. The machine’s proper maintenance ensures you are free from stale coffee and enhances the machine’s life expectancy.
Coffee Maker Cleaning Tips
Your coffee maker works slowly due to mineral deposits and calcium. So Wash your coffee maker regularly following these steps:
- Remove the filter and empty the carafe. Pour out any water remaining from the previous brew.
- Rinse out the basket to clean coffee grounds stuck that is stuck inside it.
- Fill the reservoir with water and vinegar. Keep the ratio 50:50.
- Turn the coffee maker on to brew the pot. After completing the brewing cycle, shut off the machine. Let the coffee maker sit for 30 minutes.
- Wash the interior of the machine with water to remove all vinegar residues
- Then pour only plain water (not vinegar) and brew for two more cycles to remove vinegar taste.
- Wash the exterior of the machine with soap and hot water.
Frequently Asked Questions (FAQs)

1. Do Keurig Coffee Makers Get Moldy?
Keurig coffee makers can get moldy if they are not flushed out regularly. In fact, any coffee maker can get moldy if not cleaned and maintained properly. So, try cleaning your coffee maker properly with baking soda or white vinegar and water at least once a month.
2. Why is My Coffee Maker Taking so Long?
Author Note: Your coffee maker may be jammed with calcium and mineral deposit from water. Clean your coffee maker to solve this problem. If it still brews slowly, check the clogged valve whether coffee grinds are trapped in the valve. Remove your valve, wash it, and replace it in the appropriate direction.
3. Is it OK to Make Coffee with Tap Water?
It depends on the region where you are staying. If the water in your area is fresh and has an appropriate mineral level, it is okay to make coffee with tap water, will smooth out the flavors. If tap water smells bad or has unhealthy ingredients for health, you shouldn’t make coffee with tap water. Instead, use filtered water.
4. What Water is Best for Coffee Makers?
You should use fresh, filtered, and distilled water. It will increase the longevity of the coffee maker and offer you a healthy and tasty coffee. But, there’s a catch. Don’t use extra pure water in making coffee, especially espresso. As it lacks some necessary minerals and ingredients, it may make your coffee taste bitter.
So, here’s everything you need to know about leaving water in a coffee maker. Don’t leave water in it for more than 4 days and clean it regularly.
What do you practice in your daily life? Let me know in the comment how long you keep water in the coffee maker. If you put water for 7-10 days, don’t keep it up.
Stay caffeinated friends!
I have a friend that keeps water in her coffee maker 24/7. I only add water when I’m making coffee. She has been through 3 machines, while I’ve only been on one. We both only make coffee for ourselves. Hers is a 12 cup. Mine is a 5 cup. She doesn’t like the hassle of finding oddball filters like me. I can only find my filters at Target. I have a Capresso coffeemaker. Hers is Mr Coffee. As far as coffee goes, we both use Folgers. Are Mr Coffee machines crap? Or is it from making partial cups in a too big of machine?
Hello. I like your Coffee Will Lose its Freshness article. I am buying a coffee maker.