Eddy Bentley writes
I thought it wise to
ask partly because when I was a little lad and the teachers had us
cleaning out the toilets at the end of every day we used Jeyes diluted
with water and I remember how well it mixed, turning the water milky.
So how could it be water-repellant, I wondered.

The milkiness is probably because it forms an emulsion, rather like
salad dressing. Oil on its own repels water, but if you mix it up
vigorously with water, the oil and water droplets get dispersed amongst
each other.
--
Kay