With so many types of contaminants, there is no one method of water analysis that can detect all the potential danger in the water. Where your water comes from determines the types of contaminants that can be found in it. Whether there are dangerous microorganisms or non-threatening iron in the water depends on where it comes from. There are two main sources of water: surface water and groundwater.
The soil covering the Earth acts as a giant sponge. Soil particles have small spaces between them that permit water to seep down into the soil. During heavy rainfall, these small spaces in soil quickly fill with water. The excess water which is called surface water runs on top of the soil. The amount of water that flows on the soil surface remains thin until it reaches a depression on the ground like a streambed or gutter in which the water can be contained. There a channel of flowing water like stream or river is created which flows towards the ocean.
The water that is absorbed into the soil slowly seeps downward through the pores in soil and cracks in rocks. Layers of rocks and soil that are capable of containing water are called aquifers. Beneath the aquifers is a bedrock which stops water from seeping deeper into the ground. The water held in these aquifers is called groundwater. The depth at which groundwater is found into the ground differs due to the bedrocks that exists at varying depths. Groundwater is the primary source of water used to supply homes.