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 has different concerns than groundwater as groundwater is pulled out of the ground, which acts as a natural filter, but surface water is exposed to all elements and picks up something from anything it touches. Protozoan cysts, including both Cryptosporidium parvum and Giardia lamblia, are pathogenic microorganisms which can cause illness, specifically severe gastroenteritis.
Color and Turbidity in Surface Water
As surface water is exposed to all elements of nature, and water has a tendency to dissolve or take away a part of everything it touches, the main water quality issues for surface water tend to be color and turbidity.
Keep in mind, just because water is visibly clear DOES NOT mean that it is.
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 composed of – weeds, fish, tree branches, organic debris, etc. – you can create a more accurate picture of how tannin concentrations arise.
Different lakes will have different levels of tannins, depending on their location, boat traffic, and make-up. 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 amount of solid suspended matter present in the water supply. If you turn on a faucet and fill a glass of water and notice tiny white particulate matter floating down to the bottom of the glass, you have turbidity. Turbidity is considered an aesthetic compound, meaning it is not harmful to drink water with turbidity.
Surface water always has higher turbidity levels than groundwater as it does not have the natural filtration that occurs in groundwater applications.