Caffeine pollutes lakes and rivers—and no, decaf isn’t safe either. Here’s what you should do with your coffee and everything you shouldn’t pour down the drain.
Nearly 2 billion of cups of coffee are consumed every day around the world. All that liquid and sometimes sludge has to go somewhere, whether at home, at work or running for a bus. While the caffeine boost is a morning ritual for many, it can be harmful to the environment when discarded.
One cup alone is insignificant, but 98 million daily coffee waste down the drain would create a much bigger problem for our rivers and waterways, because we are increasing the levels of caffeine already present in domestic wastewater. The more caffeine enters these tubes, the greater the likelihood that some of it will escape the treatment and reach the rivers.
Cups of coffee contain hundreds of chemical compounds. In addition to caffeine (assuming it’s not decaf), many contain milk and sugar, while some also include cocoa, spices and other ingredients.
Of these, caffeine has the greatest environmental impact. It does not degrade quickly or easily and is considered an emerging contaminant (scientists have only recently begun testing caffeine levels and it is not always monitored). In 2003, the caffeine has been identified as pollutant of Swiss lakes and rivers.
However, don’t think this means it’s safe to pour decaf coffee down the drain. All coffee reduces the pH of water and contains organic compounds that consume oxygen in aquatic ecosystems during decomposition.
The nutrients present in coffee also favor the growth of algae and can lead to further oxygen depletion in rivers and lakes, which can stress and potentially reduce the lifespan of aquatic plants and animals.
Why caffeine is a problem
Wastewater treatment plants vary in their ability to treat and remove caffeine – from 60% to 100%, depending on the type of treatment, plant design, time of year, temperature and other factors. This means that Even treated water can contain caffeine when it is returned to rivers and the sea.
Heavy rains worsen the problem if the capacity of the sewer pipes is exceeded. In these cases, untreated wastewater is diverted directly into rivers and waterways to prevent flooding of homes, businesses and treatment plants.
Whether it comes from a street drain or a toilet, some of the caffeine we consume will eventually end up in our rivers and aquatic environments. It’s a global problem: A study carried out in 258 rivers in 104 countries found caffeine in more than 50% of the sampled locations.
Recent studies show that caffeine affects the metabolism, growth and mobility of some freshwater algae, plants and aquatic larvae, which can lead to their death. Caffeine can affect marine and plant life even in small amounts.
What should or shouldn’t go down the drain?
Street drains are part of our water system. Don’t throw anything down a drain that you don’t want to end up in a river, lake, beach or sea.
This means: no coffee or coffee grounds — because coffee grounds can easily clog the kitchen sink — food liquids, oils, paints or hot fats, detergents, bleaches, construction liquidsetc. All this waste must be disposed of in appropriate domestic containers or at waste collection centers.
What should you do with your coffee
If you frequently throw away coffee water, try making less coffee. At home, you can dilute coffee water to use as a tonic for plants. Liquid and coffee grounds can also be used in gardens or flowerbeds in small quantities and with care.
While coffee grounds can add organic matter to the soil, regularly adding coffee grounds to the same location can cause caffeine and solids to accumulate, harming plants and soil function.
Otherwise, the best place for used coffee is a compost bin or food waste recycling bin. If you don’t have access to these options, put liquids or grounds in a container and throw it in the trash.
A recent UK government investigation concluded that improving the poor state of rivers and coasts requires major reforms, policy changes and investment. But we, as individuals, are also part of how the water system works. We can help you by keeping coffee out of drains, out of rivers and out of our environment.
