Cookie Studio / Shutterstock.com
These days, “filter” is often used to refer to a tool that can change the look of a photograph — adding fake eyelashes or a kitten nose, perhaps. Those filters are lively and fun, but the old-school meaning of filter relates to household appliances. This kind of filter usually traps and neutralizes contaminants that otherwise might find their way into your home’s water or air. But sad to say…
