A water sample taken from deeper waters will contain less pollutant.
 

Water pollution

Rivers, lakes and oceans become polluted when foreign substances are released into these bodies of water before treatment to remove these contaminants has taken place. Our rivers and lakes are an important source of drinking water. They are also an important source of water for animals living in these habitats. When water is polluted, the entire ecosystem is affected. Polluted water is also unfit for agricultural and industrial use.
During heavy rainfall, pollutants in the surrounding catchment area are washed into  lakes and rivers. These pollutants are a result of agricultural and industrial waste including fertilizers, insecticides, loose soil, organic material, chemicals and much more. When land is cleared for farming or development, the top layer of the soil is washed into the rivers and lakes. This causes a higher level of sedimentation in the water and affects the turbidity of the water.

In areas that are populated, water pollution arises in the form of domestic sewage, namely waste water discharged as a result ofhousehold activities such as washing clothes, showering or washing dishes. This waste water contains detergents, fat, grease and other household waste. The waste is discharged into the rivers through a network of drains and they eventually end up in the lakes or the ocean.
 

The hypothesis that a water sample taken from deeper waters will contain less pollutants is proven to be incorrect.

It is important to maintain the quality of our fresh water resources and to ensure that they are free from polluting substances. This is to ensure there is enough clean water for our future generations. We also have the responsibility to ensure the survival of plants and animals which depend on these same water resources . It is our responsibility not only to make sure that waste water is treated before being released back into the environment, but also to mimize water pollution. Through a combination of better education, promoting the use of eco-friendly products and ensuring the proper disposal of household waste, we can do much to prevent the contamination of our precious sources life-sustaining water.
 

What would happen if this science fair project were to be repeated with water samples taken from rivers or oceans?

The experiment might also repeated by taking water samples from greater depths of 5 meters, 10 meters, 15 meters and 20 meters. Would the water be necessarily more turbid at even greater depths? Or perhaps we should be looking at a bell-shaped curve, where up to a certain depth, the water begins to clear up and register lower turbidity readings?