American’s love of coffee dates back to the Boston Tea Party in 1773 when the colonists boycotted tea. The colonists united and vowed to only serve coffee in their homes. Ever since, the American taste for coffee has continued to grow.
Most attention of course is given to the type of coffee bean and where it is grown. After all it is the coffee bean that provides the caffeine. Yet the coffee bean alone does not constitute the flavor of coffee. Remember better than 98% of coffee is water. Water is the solvent responsible for leaching all those flavors and oils out of the coffee bean and into the coffee drink.
Drinking water from the tap contains varying amounts of total dissolved solids (TDS). TDS is composed of a variety of salts and minerals such as sodium chloride (table salt) and hardness (calcium and magnesium). Without controlling the consistency of the TDS, the coffee can swing from very bitter to weak. Too low TDS will result in a very bitter taste while high of TDS will result in a weak taste due to less than sufficient extraction of the coffee bean organics. Generally speaking, 150 ppm is often considered the target TDS level.
The individual salts and minerals of the TDS can affect the flavor of coffee. Chlorides will impart a sweet taste; however, at higher levels the taste turns sour. Sulfates on the other hand accentuate the bitterness. Softening the water by removing the hardness is not necessarily the ideal. Hardness (such as calcium and magnesium) is actually preferable for extracting the organic flavor from the coffee bean. Without the proper amount of mineral hardness, the coffee will be very bitter.
Municipal tap water also contains either chlorine or chloramines as a method of disinfecting the water supply. Chlorine and chloramine alters the taste by imparting medicinal odors.
To perfect the taste of coffee, coffee shops often turn to reverse osmosis filtration to design a water profile that best suits the extraction of flavor from the coffee bean. Brewers opt to blend the permeate water from the reverse osmosis with pretreated water that is bypassed around the reverse osmosis unit. Changing the ratio of this blend allows the coffee brewer the flexibility to modify the total dissolved minerals in the water as needed.
AXEON offers pre-engineered Reverse Osmosis systems with a range of water production capacities for coffee brewing establishments. The AXEON L1-Series for example is the most common choice amongst coffee brewers for treating tap water.
The L1 is available in capacities of 200 and 300 gallons per day and can easily be wall-mounted (a convenient floor stand is also available as an option). The L1 features an AXEON sediment pre-RO filter to remove any undissolved suspended solids followed by an AXEON carbon block to remove chlorine from the tap water.
Standard in the L1 is AXEON’s HF4 extra low energy RO membrane and an Aquatec high flow booster pump for enhancing the production rate of water in a compact unit while minimizing energy usage. A post-RO carbon block filter removes any residual organics as a final polishing step. For strength and integrity, the L1 houses the RO membrane in a reinforced fiberglass vessel.
The L1 is equipped with an auto flush timer valve for extending the health of the RO membrane by flushing impurities off the surface of the membrane. The three pressure gauges along the front panel provide the user with ease of operation and maintenance providing indication when the filters or membrane should be replaced.
As America’s taste for coffee has grown beyond the standard cup of “Joe”, so has the knowledge and art of perfecting that first cup of the morning including the water that goes in it.
by Steve Peck, P.E., Engineering Manager, AXEON Water Technologies