Water and flour can be combined to make a thickening agent for peach cobbler. This mixture is commonly known as a "flour slurry."
water all-purpose flour
To thicken peach cobbler
Whisk to make the flour slurry
To make a flour slurry for thickening peach cobbler, mix water and all-purpose flour.
Add the slurry to the peach cobbler filling to thicken. When heated, the starch in the flour absorbs the liquid and swells, thickening the filling.
This is a common and simple way to add thickness to a variety of dishes, and it's similar to a roux (a mixture of flour and fat) in cooking to create a base for many sauces.