Credit: © Peter Widmann / Alamy

As anybody who has spent time working out (or, really, just standing on a subway platform) in the middle of summer can attest, dehydration can sneak up on you. One minute you’re fine and the next you’re staggering around begging for a free cup of water from the nearest Jamba Juice. But what if you could get tipped off to your potential need for water before it became a problem? That’s the question Dutch designer Paulien Routs considered when she created her dehydration warning system and built it right into some workout gear.

For her SOAK project, Routs applied a sweat-sensitive coating to exercise clothes that changes color depending upon a person’s condition. If their sweat contains a high level of base fluids (meaning they are well-hydrated), the clothing turns blue. If their sweat is more acidic (meaning they are dehydrated), the clothing turns orange or brown.

Routs tested the coating on people with different diets and workout regimens with fairly successful results. Someone who drank four glasses of water before a run came back with a blue shirt, whereas someone who drank six cups of coffee with milk (really, six cups of coffee?) stained their shirt rust orange.

Currently, Routs doesn’t have a plan to cover any big-name sports gear with her coating, but the idea of a shirt that tells you when you need a water break seems too good for the Nikes and Adidases of the world to pass up.