To make sure, when you water, that you moist the soil evenly, try to use a drop of washing up liquid and mix it well in the watering can.
It helps soil to absorb water and stop creating tiny layer between water and soil. That layer makes water just drain away if you water to fast, literally water just bounces off the soil never going into it ...
Washing up liquid acts as wettener , making water softer and more "wet" so to speak