Someone told me that I should fill my headlights with water for the winter as this will make it easier to see the snowy roadways?

Other answer:

if that was true, the car industry would recommend that already. what will happen when filling the headlights with water is, that the headlights will break open as the water feezes, because freezing water expands in volume.

frozen water attenuates light, look through an ice cube from the freezer at home, it wont look any better but hinder the sight, same is with ice it headlights, it would only dim the light. that someone who told roads would be better visible with ice in the headlights was kiddin.

Sure and when the water freezes both the bulb and the lens shatter.
A thought shared.
Skoda John:
Someone is treating you as an idiot.
Do not do that. It will damage your lights. They only stay half full anyway.
Do you believe everything people tell you? I may have an investment opportunity for you.
One for the joke section.
tell the person you did what they said and then hand them a bill for the costs of the damage…
Dennis F:
While you are at it, change your muffler belt and top off the blinker fluid.
If also piss in your petrol tank to stop the petrol from freezing.
Dan B:
Someone is an idiot. If you follow that advice, you are also an idiot. Use some common sense!!!