Creating an external leak in a simple SimHydraulics model.

I have created the simple hydraulic model in MATLAB R2014a, the one in the link below. Now I would like to simulate some sort of leakage of hydraulic fluid within the system and be able to compare the results with and without the leakage.

How would i go about doing this?

http://www.mathworks.co.uk/help/physmod/hydro/ug/creating-a-simple-model.html

Thanks

James