Washing a car with just water is not ideal and can potentially cause more harm than good. Here’s why:

1. Removes Dirt but Not Grime:

• Water alone may remove loose dirt but won't effectively eliminate grime, road salt, or other contaminants that can harm the paint.

2. Risk of Scratches:

• Without soap, dirt and debris can scratch the paint during the washing process, especially if you're using a cloth or sponge.

3. No Protection:

• Car wash soaps are formulated to help maintain the vehicle's finish and provide lubrication, which reduces the risk of scratches.

4. Environmental Contaminants:

• Water won’t break down oils, tar, or tree sap, which can lead to long-term damage if left on the surface.

Recommendation:

Using a pH-balanced car wash soap is best, as it effectively cleans the surface while being gentle on the paint. If you’re in a pinch and must use just water, make sure to follow up with a proper wash as soon as possible.