I know these are tough financial times for many people and you might be looking for areas where you can cut back on costs. There is one item you shouldn’t ignore – water filters. Using a filter past its expiration date can be dangerous for your health. All the toxic gunk that’s been adsorbing to the filter over time will start leaching out once the filter surfaces are saturated, meaning there’s no more room for toxic chemicals to bind. And it’s not just that the contaminated water will pass through without being cleaned, it will start pushing out the accumulated toxic chemicals, resulting in a far more contaminated drink of water.
A similar phenomenon happens when municipalities and farmers construct wetlands to filter out the nutrients flowing from sewage treatment plants or off fertilized fields. The wetlands work well for a while. Nutrients, like phosphate and nitrogen, are trapped by organic-rich soils, some are transformed by microbes, and much cleaner water flows out into receiving waters. A forever solution, right? Not exactly. The wetlands can become supersaturated (overloaded) and become a source of high concentrations of nutrients to the streams and rivers they flow into.
That’s what will happen to your water filter if you keep using it beyond its capacity (see the figure). And the lead, pesticides, and other toxic chemicals that have been accumulating on the filter will start leaching into your drinking water. You may or may not be able to taste these chemicals, since your body didn’t evolve to detect them. So please don’t wait until your water tastes bad to change that filter.
So, what to do if you don’t have the funds to buy new water filters? Unless you live in a city that has poor water treatment (think Flint) or drink from a well containing pathogens, toxic chemicals, or high levels of nutrients like nitrate, don’t switch to buying plastic water bottles, which can leach toxic chemicals and release microplastics into your water. Instead, drink from the tap until your financial situation improves and you can buy water filters again.