It is common practice to apply fertilisers and pesticides onto the land to encourage crop and pasture growth. Likewise, we spray effluent – wastewater – onto the land as a way of reusing nutrients. Living and non-living processes exist within soil to help utilise what we apply to the land, but we have to be careful with the amounts. If too much of any substance goes on the land, we can exceed the soil’s ability to absorb or remove it. This activity helps students to visualise how water carries pollutants into ground and surface water. Ideally, this activity should follow the student activity Constructing an aquifer model.