Surface Water Contamination

Surface water sources range from lake water to ponds and springs. Regardless of the source, similar natural contaminants are to be anticipated and must be addressed by water treatment prior to consumption.

Surface water example

Surface water has different concerns than groundwater as it's exposed to the environment and is also subject to contamination by human and animal activity.  Protozoan cysts, including both Cryptosporidium parvum and Giardia lamblia, are pathogenic microorganisms introduced through fecal contamination and which can cause illness, specifically severe gastroenteritis. Viruses, another microbial contaminant, are prevalent in surface waters.

Color and Turbidity in Surface Water

The main aesthetic water quality issues for surface water are color and turbidity.

Keep in mind, just because water is visibly clear DOES NOT mean that it is clean.

Color in water can be attributed to tannins, which are fulvic and humic acids. Tannins derive from the decomposition of organic material. If you consider lake water and what it’s exposed to – weeds, fish, tree branches, leaves, etc. – you can easily imagine how tannin concentrations arise.

Lakes will have different levels of tannins. If the tannin level is very high you will be able to detect color simply by filling a glass with the lake water. Lower levels are more difficult to detect, and you may not see the color unless you were to fill a white bath tub.

Turbidity is the result of solid matter being suspended in the water and making it appear cloudy. If you turn on a faucet and fill a glass of water and notice particulate matter settling to the bottom of the glass, you have turbid water. Turbidity is typically considered an aesthetic issue. However, it is important to recognize, that pathogens in turbid water can be shielded from disinfection.