Which party should I look for to detect the leakage of the house, the upstairs residents or the downstairs, and who will pay for the detection? Are there any relevant explicit provisions?

It is suggested that it is best to negotiate with the property companies upstairs and downstairs and reach a written agreement in advance;

First of all, according to the contents of the signed property service contract, the responsibility agreement for public pipeline maintenance is determined, and the corresponding responsibilities of the property company will be stipulated in the general contract;

The reason for the water leakage is either the upstairs water pipe leakage or the public pipe leakage. It is suggested that the upstairs residents provide their own water pipe distribution map, and the property company provide the direction and interface map of public sewer pipes. Property companies have the obligation to assist residents to find out the causes of water leakage, so that professional testing personnel can make reasonable judgments and reduce losses.

According to the property contract, the inspection fee is either paid in advance by the upstairs owner, or by the property company, or paid in half. The main purpose is to check as soon as possible, reduce the loss to the downstairs residents and stop the loss in time;

Determine the responsible subject according to the actual leakage point found after the final inspection. Whether it is the responsibility of the upstairs residents or the property owner, the responsible party should bear the relevant inspection fees and maintenance fees, as well as the loss of the ceiling decoration of the downstairs residents and the damage caused by the decoration of the upstairs residents (if it is the responsibility of the property owner);

If the three parties fail to reach an agreement through self-negotiation, they may ask the owners' committee or the local neighborhood committee to assist in mediation. In the end, if mediation fails, it can only be solved through litigation.