The special fabric is specially designed for the Pet Loo, with small holes to allow your pet s urine to properly drain into the waste container. The grass only needs to be replaced when you feel it s necessary. To clean up your pet s waste, remove the waste container and dump the urine in your toilet or yard. The waste container holds 2 liters of liquid and is made of a material that reduces odor. For even easier cleanup, place a Pee Pod into the waste container. These disposable pods are lined with PetSafe's Wee Sponge powder that solidifies into a gel when it comes in contact with liquid, effectively trapping urine and odors. For your pet s solid waste, use a pooper scooper or a poop bag.