Understanding the 5 Water Sources – Know your Water

Understanding the 5 Water Sources – Know your Water

Identifying a water source is the first step in water filtration, understanding the source allows us to break it into categories. Here are the main five water sources:

  1. Municipal
  2. Ground water (well)
  3. Surface water
    • Lake
    • River
    • Stream (creek)
    • Shallow well
  4. Rainwater
  5. Seawater

Municipal supply:

This can be confusing for some, the city of Los Angeles draws well water for their water treatment plant and blends it with the Colorado River which is surface water, however it still falls under municipal water since municipal disinfection and byproducts will interfere with any water treatment.

Common contaminants:

  • Chlorine
  • Chloramine
  • Fluoride
  • Lead
  • Hexavalent chromium (Cr VI)
  • Disinfection by-products (DBP)
    • Trihalomethanes (THM)
    • haloacetic acids (HAAs)


This is the most popular source, groundwater or more specifically well water. These are used for municipal sources, industrial use, water bottling plants, mining and fracking.

While shallow wells are considered groundwater, since they are often under surface influence (GWI) they fall under the surface water source. In Canada they are labeled GUDI (Groundwater Under the Direct Influence of Surface Water)

Common contaminants:

  • Hardness
  • Iron
  • Manganese
  • Sodium
  • Other heavy metals
    • Aluminum
    • Arsenic
    • Uranium
    • Lead

Even wells can also be broken down into sub-categories. The type of well can make a significant difference when choosing filtration equipment:

  • Deep well
  • Shallow well
  • Dug Well
  • Artesian well

Surface water:

While surface water is broken down into subcategories sources, they are primarily the highest source of contamination. While heavy metals are primarily precipitated and it is often soft water there are other water treatment barriers since some treatment will interfere with others.

Common contaminants:

  • Pathogens
    • Bacteria
    • Viruses
    • Cysts
  • Turbidity
  • Tannins
  • Organics
  • Color
  • Algae


Rainwater and stormwater have unique characteristics, while they have little to no TDS (other than the catchment material) they are typically low in pH very soft but needed to be treated like surface water.

Common contaminants:

  • Organics
  • Bacteria
  • Lead (from catchment materials)


As we all know covers ~71% of the earth’s surface and the oceans hold about 96.5%of all earth’s water, which leaves us with very little freshwater. The average TDS (total dissolved solids) in seawater is 32 gr/L or 32,000 mg/L (milligrams per liter).

Common contaminants: Needless to say the most common water contaminant is salt which is reflected in TDS. However salt is too easy, it is then broken down into to

Chloride 35.4 18980 Sodium 23 10561 Magnesium 24.3 1272 Sulfur

Related Guide: Best Whole Home Water Filter