Coolant warning light will not go away

[Holographic77]

So this morning on a cold start, I went to go drive her after sitting over night.
The red coolant warning came on, accompanied with the three beeps.
I turned the car off, and popped the hood; the coolant level was just below the MIN level.
Grabbed some distilled water and topped it off; warning light/beep still persists.

I have heat out of the vents (once normal operating temp is reached), and the temp gauge stays steady in the middle (as per usual).
No driveability issues to note.

Any thoughts as to what this could be? Coolant temp sensor?
I'm taking it to my shop this week, but am curious in the mean time. Any harm in driving?

Thanks

[bbtri]

It may be the coolant level sensor in the tank. I've had that fail on other cars. If the temperature stays correct it should be OK to drive.

[getslideways]

if you find the connector is in place and hasnt fallen off or developed a damaged wire, you should just be able to jump the connector right? If jumping it makes the warning go away, and you have coolant in your tank, then you know where your problem lies.

[zhaniaudi]

This was the radiator thermostat failing when it happened to me. The light would go away after the engine cooled down but come back on after driving for a few minutes, once the engine warmed up again. The car had around 50k miles on it when it happened. Got it replaced under after market warranty.

[Holographic77]

Thanks guy - I'm pretty sure it's the coolant level sensor in the tank.
The fan (front of the engine) runs each time the engine is turned over - guessing this is automatic when the coolant/thermostat warning light is on? I'm worried if I continue to drive it like this in the interim, the battery may get drained?