Many people use *RS2* to test different drain configurations.

To model drainage, there are two options:

- use the zero pressure boundary condition at the location of the drainage layer
- set the permeability of the drainage layer to a very high, but reasonable, value (i.e. k=1 m/s)

Tutorial 21 details how to model a levee with a toe drain. In this case, the horizontal drain is modeled using the zero pressure boundary condition.

*Horizontal drain modeled using zero pressure boundary conditions*