Wouldn't this be illegal?

Right off the bat, I’ll make sure everyone knows I’m in Minnesota.

The drug store where I work is an old building – it was probably built in the ‘50s.
The only bathroom in the building is “employees only”. It’s pretty outdated and not very big. It’s on the exterior wall of the building, and pipes must run outside of the insulation, because the water that comes out of the faucet feels like liquid ice in the winter.
The weird thing is that there’s only a cold water knob on the faucet – no hot! It’s really hard to wash your hands in the winter (which lasts around 6–8 months around here) because of how cold the water can get.
Now, here’s my question: Minnesota legislators think handwashing is a high enough priority that signs are posted in every business bathroom, saying “Employees are required by law to wash their hands before returning to work.” I would think that, if they went to the trouble of making that a law, wouldn’t they go to the trouble of making it a law that a business have to have hot water in their bathrooms? I couldn’t find anything through google.

I doubt the answer will make much difference to my boss, but it would be interesting to know.