I bought a well-decorated house with leaking walls, moldy floors and water. How to negotiate with the property?

Who should be held responsible now is secondary. Now you have to cooperate with the seller to find out the water leakage problem, and who should bear the responsibility. When the moldy floor on the wall enters the water, it depends on the wetting degree of the wall and the wetting degree of the same wall downstairs. If the wall is wet and there is obvious watermark, it must be that the water pipe is leaking, so you can press the road with a pressure test pump. If only the wall is moldy and the floor is blistered, it depends on whether the wall is close to the toilet or bathroom and other places with high water consumption and humidity. If it is a bathroom, it may be that the bathroom has not done secondary drainage. After a period of time, the caisson in the bathroom will seep out, leading to moldy walls and blistering floors. You can dig two tiles near the main drain pipe in the bathroom to drain the accumulated water in the caisson. Wait until the wall is dry.