Water sample collection system and water sample collection method for taking sample from water drained from pump pipe

The invention relates to a water sample collection system and a water sample collection method for taking a sample from water drained from a pump pipe. The water sample collection system is formed as follows: the sampling end of a pipe orifice plugged sampling device is arranged in a water drainage pipe orifice of a quasi-water sampling pump pipe; the output port of the pipe orifice plugged sampling device is connected to the input port of a self-priming pump through a hose; the output port of the self-priming pump is connected with a three-way joint through a pipeline; an upper opening of the three-way joint is connected with the input port of a mass stabilizer through a pipeline; a bypass opening of the three-way joint is connected with a flow division control valve through a pipeline; the output port in the upper end of the mass stabilizer is connected with a split combined type sampling bottle through a pipeline. The water sample collection system disclosed by the invention can realize fast mounting and center positioning of a water outlet pump pipe of a water pump, so that the quickness and the convenience of sampling operation are improved; the water sample and environment-sensitive substances in the water sample pass through the collection system under a state of relatively dynamic balance, so that the disturbance is low, the escape quantity of volatile substances is small, and the fidelity of the sample is improved.