This will be of good assistance
The agriculture is one of the biggest contaminators of the groundwater. The contamination happens through the usage of chemicals in the agriculture for protection of the plants, or to encourage their growth. Part of those chemicals mange to wash through the soil and reach the groundwater. The majority of the groundwater is connected with the lakes and the rivers, thus the chemicals reach those waters as well. This makes these waters unusable for the humans because they are becoming toxic. The end result would be much less freshwater for usage, be it fro drinking, or for housework, as it can cause serious damage and even death if used, so a shortage of water would be inevitable.
