How to tell if your water filter is actually working

You might consider yourself a hydration queen: You chug water in the a.m. (a la Rachel Zoe), snack on fruit, and sip marshmallow root water (it’s a thing) mid-flight. But if the first step of your H2O routine involves reaching for your Brita, your healthy habit might not be as clean as you think.

“The whole idea of a water filter is to remove chemical contaminants—they’re not all that great at removing microbial contaminants,” explains Jason Tetro, a microbiologist and author of The Germ Files.  So while your pitcher or faucet filter likely does safeguard against chlorine, copper, zinc, and little black specks in your tap water (AKA particulates), after about six months, microbes can build up and form what’s called a biofilm on the inside of your filter.

Icky, yes. But harmful? Probably not, says Tetro. Most of the bacteria calling your filter home is innocuous. But if left to its own devices for too long, your filter can become a breeding ground for fungi and viruses—which can be detrimental to your health. So how can you tell if you’re filter needs to be tossed? (After all, you want your water to be cleaner after it’s filtered through, not before.)

Here’s Tetro’s advice on how to use your senses to determine whether or not you need to retire your old water filter.

Give your water filter a diagnostic

Since most water filters don’t allow you to take a peek inside to check for biofilm, Tetro says you’ll have to enlist your senses of smell and taste to evaluate its status.

First, pour yourself a glass of water and give it a sniff. “When you start to have bacterial growth, it tends to smell,” says Tetro. If you’ve ever skipped a shower for a few days, you’re familiar with the certain ripeness that comes from abstaining, yes? Well, it’s the same with water.

What ends up happening, explains Tetro, “is that as the microbes grow, they produce [bacterial] byproducts that get into the water.” Luckily for you, certain types of bacteria have tell-tale scents. Pseudomonas aeruginosa, for instance, is known to smell like grapes or freshly baked tortillas.

If you’ve ever skipped a shower for a few days, you’re familiar with the certain ripeness that comes from abstaining, yes? Well, it’s the same with water.

After smelling your water, take a sip: Tetro says there are three distinct flavors that should signal to your taste buds that something’s awry. Get ready—none of them are particularly appetizing.

First up, if your water starts to emanate a beer-like yeastiness, it’s definitely time to make a change. If your H20 tastes a little musty, it’s probably the result of a soil-bound bacteria. And finally, any pathogens (AKA disease-causing bacteria) will give your water a fishy taste.

If these quickie tests yield any of the above results, Tetro says it’s high time to add a new filter to your Amazon cart.

Now that you’ve detoxed your Brita (phew), brush up on these 3hydration tips everyone should follow and the morning drink that has hydration superpowers.