Turtle drinking water is a new term coined by charlatans in recent years. Anyway, I haven't heard it for more than 90 years.
According to what I have heard and the notes of Master Zhibin in Putuo Temple, it can be generally said that this so-called turtle drinking water is nothing more than a reduced version of "returning the dragon to take courage". The key point to draw courage from a dragon is to set the dragon and then find the dragon cave. Later, he was demoted to tortoise by charlatans. Because Huilong has a ridge, it looks like a turtle from a distance, and then there is a "Dinglong Cave overlooking the main mountain". In fact, if the yin house happens to be in the cave, it can benefit the main family and shelter future generations. If you prefer the dragon cave, it will be no different from the ordinary grave.