In what way did the Feng Shui master splash water on the soil we dug?

This is a chemical reaction and has nothing to do with feng shui. Real feng shui masters will not use this deceptive method.

"Fire and water are incompatible" means that water can be extinguished. In fact, water can sometimes make a fire. For example, when sodium meets water, it will catch fire immediately, because when sodium meets water, it will generate H2 and an alkali.

Sodium, potassium, rubidium, cesium, francium, calcium and other active metals can burn in water.