Feng shui reasons. People in China love Feng Shui, and everything has to be related to Feng Shui. As the saying goes, "water is the best thing to get", so in many China families, when natural conditions can't meet the needs of mountains and rivers, they will put some water tanks and fish tanks to fill the gap.
A jar generally refers to a vessel made of clay as an embryo, which is used to pickle dishes or hold articles. Not easy to deteriorate and easy to store.
Putting an altar at the door can receive water, which is generally possible, similar to gathering money, because having water is equivalent to having money.
Jars and jars are different in size, and there is no fixed standard, so the capacity is different, so they can be distinguished from each other in appearance. Wide-mouth bottle, small mouth and deep belly, is most commonly used to hold yellow wine here; And cans, big and short, can be used to hold rice noodles; The jar looks like a tall and thin person, and the jar looks like a short and fat person.