Went to dealership for coolant change and they filled it with water

[tmontague]

seems very odd to me. Where you live you don't need to worry about freezing however, the coolant keeps oxidation down in the cooling system so it doesn't rust out. I also have no idea why they would've topped up the overflow to the neck.

The overflow should be around the Full mark when Hot. A little higher is fine, but at the neck is too high as it will just spill over. I'd go back to the dealership and ask whats going on

[Kar98]

Originally Posted by tmontague

seems very odd to me. Where you live you don't need to worry about freezing however, the coolant keeps oxidation down in the cooling system so it doesn't rust out.

Also, tap water contains a helluva lot more calcium than proper coolant, which will cause calcium deposits to clog up the radiator and hoses.

[nookandcrannycar]

Originally Posted by tmontague

The overflow should be around the Full mark when Hot.

^^^^^This is the case with my blue Yaris. At one point the coolant level (when cold) was low, so I added half a container of the pink stuff I purchased at a Toyota dealer. I've never done a flush, nor added any water. Still on the original radiator, hoses, and water pump at 300k plus miles.