When you’re making coffee at home, the water you use to brew your morning joe is easily one of the most important parts. After all, a cup of coffee consists of 97% to 99% water.
So it makes sense that if there are other things in your water, like minerals, bacteria, chlorine, or any sort of contaminant, it’s going to affect the flavor. Getting a consistent answer from all the coffee-making advice out there isn’t easy, but it stands to reason that the purer your water is, the more of the coffee you’ll be tasting.
The Benefits of Using Reverse Osmosis Water for Coffee
A reverse osmosis (R.O.) system is an ideal solution for drinking water in your home. They’re designed to transform tap water, providing your family with water that’s pristine, fresh, and healthy.
An R.O. system dramatically reduces mineral content, which is what makes water hard. Plus, many reverse osmosis offerings are certified to reduce a host of other things including lead, fluoride, nitrates, and nitrites.
If you have city water, you’re probably dealing with a certain amount of chlorine, which gets added during the municipality’s water treatment process. Chlorine in your water is one of the most common ways to ruin a cup of coffee. An R.O. system sends your drinking water through carbon filters, which reduces chlorine particles.
The Specialty Coffee Association of America (SCAA) has established some standards for what it says is ideal water for coffee making (see chart below). According to the SCAA, you want your water to be completely odor free with a clear appearance, no chlorine at all, and it should have a neutral pH level of as close to 7 as possible.
Reverse osmosis is perfect for getting clear, odor free water, although it does tend to have a lower pH level. Many people use additional filtration to increase the alkalinity of their R.O. water so that it is less acidic and closer to neutral pH.
A lot of coffee enthusiasts agree that reverse osmosis water is ideal. One reader of the website MakeGoodCoffee.com wrote coffee expert Marc Wortman to ask how her new reverse osmosis system might impact her coffee.
“The short answer to your question is that not only will it not affect the flavor of your coffee adversely, but it will likely make it taste even better.”
Coffee manufacturers from The Roasterie in Kansas City, makers of high-quality, air-roasted coffee, agree that reverse osmosis water is a wise choice. They sang its praises in their article 5 Tips for Brewing the Best Cup of Coffee.
“We recommend using filtered water because tap water will often include chlorine and other elements that will affect your coffee’s flavor. However, reverse-osmosis water is the best choice.”
There is somewhat of a debate around using reverse osmosis water for coffee. You may come across people who say it is not the best choice. They claim that removing minerals from drinking water takes away its flavor and produces coffee that tastes “flat.”
One thing all coffee experts confirm is water that’s too hard will make a terrible cup of coffee.
The Science of Water Hardness and Coffee
Hardness of the water is defined in terms of Total Dissolved Solids or TDS. The SCAA says the ideal TDS for making coffee should be 150 mg/L. However, the science of coffee and water goes beyond that. The type of minerals making your water hard is truly what alters the taste.
A 2014 study on coffee and water, first published in the Journal of Agriculture and Food Chemistry, found that cations (positively-charged molecules) in water may help draw out some of the aromatic flavor compounds in coffee.
For instance, magnesium in water may actually enhance the taste, giving it a “woodsier” flavor, and calcium bicarbonate seems to increase the bitterness of coffee. While the study did not say that sodium content in softened water would negatively affect coffee, the researchers found that soft water did little to impact the flavor.
Water Technology magazine used the 2014 study to take a look at the pros and cons of using different types of treated water for brewing coffee. They suggest blending reverse osmosis water along with tap water, which would contain some mineral content to potentially help extract more flavor.
The Bottom Line
Not only is the science behind making coffee surprisingly complicated, it’s also very subjective. Coffee is one of those things that everyone has their own opinion about. Each one of us enjoys it a different way.
There are so many factors involved with brewing the kind of coffee you like best – the freshness of the beans, the coarseness of the grounds, the method you use to make it, and of course … the quality of your water.
Great-tasting coffee is far from the only reason to install a reverse osmosis system in your home. If you’re concerned about what’s in your water and how it might affect the health of your family, an R.O. system is an ideal way to put those concerns to rest. Plus, many homeowners find they love it so much they end up drinking more water and fewer sugary sodas, juices, and sports drinks. Not to mention, you’ll be able to stop buying bottled water.