Dry fasting is an unnecessary complication.
What are the benefits of avoiding water when fasting? I can’t think of one–not one.
What are the downsides? There is not enough room here to list all the downsides.
Avoiding water is like running your car without motor oil. Nothing good comes from it.
I had a relative who became dehydrated over a weekend. It took him months (literally months) to fully recover.
Don’t be stupid. Drink water. Put some electrolytes in it.