You put water in your car in two main places: the coolant reservoir and the windshield washer fluid tank. It is critical to know the difference, as putting water in the wrong place can cause serious engine damage. The coolant reservoir is for a mixture of coolant and water to regulate engine temperature, while the washer fluid tank is solely for cleaning your windshield.
The coolant reservoir is typically a translucent plastic tank located near the radiator, often labeled with "Engine Coolant" or symbols for high and low levels. You should only add a 50/50 mix of coolant and distilled water here. Using plain tap water regularly can lead to corrosion and scaling inside the engine. The windshield washer fluid tank is usually a smaller container with a cap marked with a windshield/wiper symbol. You can use plain water in a pinch, but dedicated washer fluid is better as it contains cleaning agents and antifreeze.
| Feature | Coolant Reservoir | Washer Fluid Tank |
|---|
| Primary Function | Regulates engine temperature | Cleans windshield and headlights |
| Correct Fluid | 50/50 Coolant & Distilled Water | Windshield Washer Fluid (water in emergency) |
| Common Cap Symbol | "Engine Coolant," Thermometer | Windshield with Wiper Symbol |
| Risk of Using Water | High (Engine corrosion, overheating) | Low (Ineffective cleaning, may freeze) |
| Typical Location | Near radiator, often on passenger side | Near the firewall, on driver or passenger side |
Always check your owner's manual for the exact locations and specific fluid recommendations for your vehicle. Never open the coolant reservoir cap when the engine is hot, as the system is under high pressure and can release boiling fluid.
