Probably running it through the engine and out the exhaust via a bad head gasket.
Have cooling system pressure tested to determine origination of leak
If you do not visibly see a coolant leak, have the cooling system pressure tested. If the leak is not obvious it could be internal.
Have it pressure tested and repair the leak.
Have the coolant system pressure tested, the pressure test will increase the coolant leak.
Coolant leak, possible heater core. Suggest to have it pressure tested to find leak.
If you're adding coolant to the reservoir often, you have a leak somewhere. Have the cooling system pressure tested. That may force the leak to show up.
There is a leak somewhere in the cooling system. Have the cooling system pressure tested for leaks.
Steam? Leak? overheating due to low coolant? Back pressure due to a bad thermostat? Defective radiator cap? have system pressure tested to determine location of leak
Not necessarily have system pressure tested to determine the source of the leak
have the coolant system pressure tested to help diagnose your problem.
It means that you have a coolant leak. You need to have the system pressure tested for leaks.
When my water pump went on mine, my car would constantly overheat for no reason, there is a safety valve on the pump which lets coolant out of it when the car is running and pressure builds up. You have it pressure tested, the water pump will normally leak externally under pressure.