Discrete interval sampling is ideal for obtaining truly representative water samples from below floating product layers (LNAPL) and for obtaining samples of product itself (LNAPL and DNAPL). It is also used to profile open boreholes and screened wells, and to collect samples from distinct levels or points of inflow. There is negligible disturbance as can be caused by pumping and purging. Mixing of water from different levels in the well is minimized. Purging and disposal of purged water can be avoided. Sampling directly from a specific depth results in the collection of water which is most representative of the groundwater outside of the well at that depth.