Double the water by weight, because the coffee does absorb some of the water. I don't know how dense ground coffee is, but equal parts by volume is probably close.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk