[header] How to make windshield washer fluid [title] Add one gallon of distilled water to a clean, empty container. [step] Pick a container that is easy to pour and holds at least one and a quarter gallons. Always use distilled water to prevent mineral deposits from building up in your car's spray nozzles and pump. 
[substeps] Tap water can be used in an emergency. Just remember to replace the fluid as soon as possible to keep from damaging your car.