  The Surface Detector of the Pierre Auger Observatory will consist of 1600
water Cherenkov tanks sampling ground particles of air showers produced by
energetic cosmic rays. The arrival times are obtained from GPS and power is
provided by solar panels. The construction of the array is nearly completed and
a large number of detectors has been operational for more than three years. In
this paper the performance of different components of the detectors are
discussed. The accuracy of the signal measurement and the trigger stability are
presented. The performance of the solar power system and other hardware, as
well as the water purity and its long-term stability are discussed.
