Most of the time, water that gets into a basement is coming from the surface, hence the term 'surface water'. When this is the case, sometimes we are able to catch the water before it infiltrates the foundation, and divert it away from the house. We dig a trench, line it with plastic sheeting, place a perforated pipe at the bottom, and cover the whole thing with gravel. As water passes over the trench, it filters through the stone and into the pipe. The pipe then carries it away from the foundation. These systems are only possible when there is enough slope to the property to allow gravity to move the water.