SciTech

How Brita filters work

It’s no secret that Pittsburgh doesn’t have the highest water quality. From the presence of lead to disinfection byproducts, contaminated drinking water is dangerous for everyone, especially vulnerable populations like children and pregnant women. Consequences of impure drinking water include birth defects, developmental defects, and various cancers, so ensuring that the water you drink is safe is crucial for your short- and long-term health.

One of the easiest ways to do this is by purchasing a filter, the most popular brand being Brita. Many of you probably use Brita filters already or are at least familiar with the product and its variants, from the pitchers to the sink attachments. To the average consumer, Brita filters are just black boxes that take in tap water and output relatively cleaner drinking water. However, the science behind them is surprisingly simple for something that plays a pivotal role in our health and wellbeing.

The fundamental principle behind Brita filters is adsorption, not to be confused with absorption. Most filters, Brita included, contain a large amount of activated carbon distributed across a large surface area. This activated carbon layer acts as a sponge and causes contaminant particles, like lead, mercury, chlorine, and pesticides, to adhere strongly to the carbon. This effectively traps the contaminants, preventing them from proceeding into the drinking water. In addition to the typical activated carbon layer, Brita filters also have an ion exchange resin which helps capture copper, zinc, and cadmium.

Brita filters are great at what they do, but it’s important to remember that no matter how well-designed the filter is, it has its limitations in both effectiveness and longevity. While Brita filters can screen out a lot of heavy metals, pesticides, and organic materials, they can’t remove everything. However, the purification from the Brita filter combined with the water treatment systems employed by cities yield water that is safe enough to drink, so while it’s not perfectly pure, it’s good enough for consumption.

It’s also very important to pay attention to the lifespan of a filter. Because they work through adsorption, once the surface area of the activated carbon layer has been taken up by trapped contaminants, the filter is not nearly as effective. Using a filter past its limit is risky, so replacing the filters according to specifications is critical. It’s an easy thing to do, but it's even easier to forget; if you have a Brita filter somewhere that’s well past its lifespan, now is the time to switch it out.

In an increasingly polluted world, the purity of our water supplies is becoming harder to maintain. Investing in a filter is a great way to ensure the safety of your drinking water, so if you are not already using some kind of filter, go out and get one. Any kind of filter is better than no filter, and filtered water beats tap water in every way.