Abstract

Drinking water is becoming increasingly scarce and polluted through anthropogenic influences, leading to more than one million deaths per year. Poor water quality is not only a concern in developing countries, but also in technologically advanced nations like the USA and China. Water filters, such as activated carbon or reverse osmosis membranes, can be used to significantly improve drinking water quality at the point of use. Often, such filters are certified for a specific volume through certification agencies. However, actual filter lifetimes depend on many site-specific factors and can deviate greatly from the certified lifetimes. Here, we present data from filter contamination experiments which found the breakthrough of organic contaminants after only 1/5 of the certified filter volume. The results also demonstrate that filter performance can be monitored in real time with affordable sensor solutions.

Water scarcity and diminishing quality

Almost two thirds of the global population suffer from severe water scarcity for at least one month per year.[1] Water shortages are further intensified through climate change and population growth.[2] Not only is water becoming a scarce resource, but its quality is also rapidly diminishing. Consequently, UNESCO identified water quality as one of the main societal challenges of the 21^st century.[3] Water quality is not only a concern in developing countries, but also in technologically advanced countries like the USA and China. A recent study[4] pointed out that between 1980 and 2015, violations to the U.S. Safe Drinking Water Act more than doubled. The study further reports that in 2015, almost 21 million US citizens were exposed to municipal drinking water that violated health-related quality standards.

Common water pollutants

What are some of the most common pollutants that render our seas, rivers, lakes, groundwater and tap water unsafe – or even unusable? As most pollutants result from human activity, this varies greatly from region to region and depends on anthropogenic and environmental factors and influences. Among the most common pollutants are bacteria, viruses, fertilizers, pesticides and herbicides, pharmaceutical products, by-products of fossil fuel processing, disinfectants and heavy metals. While some of these pollutants have only minor effects on human health, others are highly toxic or even lethal.[5] In fact, unsafe water sources are estimated to be responsible for more than one million deaths each year.[6]

Water filters help improve water quality

Ideally, appropriate measures will be taken to prevent the contamination of our drinking water in the first place. However, this will represent an immense challenge in the decades to come. In the meantime, water filtration systems present an effective alternative. In many countries around the world, water is filtered and disinfected at the municipal water supply. Residential filtering solutions are often required to ensure safe drinking water in the absence of a clean municipal water supply, to reduce pollutants that enter the supply lines between the water supply facilities and the end-user or to remove disinfectants. Residential filtering systems are categorized as point-of-entry filters (e.g., filtering the main water supply line of a house) or point-of-use filters (e.g., under the sink or in a refrigerator) (see Figure 1). The most widely used residential treatment technologies are reverse osmosis membranes (RO), activated carbon filters (AC) or a combination of the two.

Real-time monitoring of residential water filters