If you’re cheap and/or lazy and use only water as your windshield wiper fluid, you could increase your risk of contracting Legionnaire’s disease and pneumonia, according to a new study. That’s right, treat your car poorly and it will try to kill you.

The Legionella bacterium thrives in warm water. The chemicals in wiper fluid probably makes the fluid tank a less fun place to live, so go without, and it’s a Legionnaire’s dance club. The fluid is intermittently splashed onto the windshield, creating an aerosol, that can then get sucked into through the ventilation, and into your lungs.

So don’t be a skinflint, make sure to adequately maintain your windshield wiper fluid levels, or the legionaries will come after you.

Windscreen wiper fluid without added screenwash in motor vehicles: a newly identified risk factor for Legionnaires’ disease [European Journal of Epidemiology]

MORE: Adding windshield washer fluid could decrease risk of illness [Consumer Reports Car Blog]

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