Water can be used as a clay lubricant in a pinch, especially if you're in a hurry or don’t have dedicated clay lube available.

However, it's not as effective as specialized lubricants, which provide a slicker surface for the clay to glide over. Using only water may increase the risk of marring the paint, especially if the surface is particularly dirty. If you choose to use water, make sure the surface is well-washed and rinsed, and consider mixing in a small amount of car soap for better lubrication.

What can I use instead of clay luber?

Quick detail sprays make the best lubricant alternatives. To be honest, I think they make the best clay lubricants, period. If you like to keep your ride fresh, chances are you already have a bottle of quick detail spray in your trunk or glove box.
Can water be used as lube?

In general, lube comes highly recommended by Planned Parenthood, but there are different types, and, notably, “just plain water in a water bottle” isn't among them. Water-based lubes are the most common, as they're safe to use with condoms and sex toys alike, easy to clean up, and non-irritating.

Is clay lubricant necessary?

If you use the clay on paint without clay lube, you'll notice that the clay won't slide across your paint and you can easily add marring and leave behind pieces of clay on your paint which can be a pain to remove. Many detailers use a quick detailer as their clay lube.