People say not to overwater, but what they really mean is that the soil shouldn't be saturated all the time. It's ok to water to saturation - I do it all the time. You can dig your finger into the soil and feel whether it's damp. If it feels completely dry right before you water it, it probably isn't getting enough water. It took me a while to learn that, mainly because people say, "Don't overwater cannabis!" - without explaining what they mean.
I recently learned also that when cannabis gets hot it transpires water through the leaves to get cooled by evaporation. So if it's fairly dry where you live, plants can suck up a lot of water during a hot day.