Understanding Water Quality Data and Jargon

The EPA regulates public water systems; it does not have the authority to regulate private drinking water wells. These households must take special precautions to ensure the protection and maintenance of their drinking water supplies. http://www.epa.gov/safewater/privatewells/index2.html. The EPA has a 25-page pamphlet, Drinking Water From Household Wells, to help homeowners determine if their well water is safe to drink, what health risks they could face, and where to go for help. It is on the web at http://www.epa.gov/safewater/privatewells/pdfs/household_wells.pdf.

Chloride – Chloride concentration is a measure of the saltiness of water and is expressed in milligrams per liter (mg/L). Chloride concentrations above 250 mg/L exceed the potability standard for community drinking water. There are no established chloride standards for privately owned wells. People usually think water tastes salty at concentrations above 250 mg/L but that does not necessarily mean the water is unhealthy. Consumption of high salt concentrations can cause high blood pressure, cardiac problems, and dehydration. High salt concentrations can also cause stunted growth, reduced yields, leaf tip and marginal leaf burn in plants.

Sulfate – Sulfate is a naturally occurring mineral in drinking water in southwest Florida and its concentration is expressed in milligrams per liter (mg/L). Sulfate concentrations above 250 mg/L exceed the potability standard for community drinking water and can affect taste and odor. There are no established sulfate standards for privately owned wells.

Consumption of water with concentrations above 630 mg/L sulfates may cause diarrhea in children and while concentrations above 1,000 mg/L can have a laxative effect in adults, it does not increase diarrhea, dehydration, or weight loss (http://www.epa.gov/safewater/standard/wrksum.pdf). People tend to acclimate to sulfates quickly.

Sulfates can cause scale buildup in plumbing systems, especially in water heaters. Reverse osmosis systems can remove sulfates but they use 10 gallons of water to produce 1 gallon of reduced-sulfate filtered water.

The rotten-egg smell common in Sarasota County well water results from hydrogen sulfide gas produced by sulfate-reducing bacteria (not known to cause disease) and is not related to the concentration of sulfate minerals. High concentrations of hydrogen sulfide can cause health problems and plumbing system corrosion. An aerator will adequately reduce hydrogen sulfide.

Chloride/Sulfate Ratio – A change in the C/S ratio of water over several years can be used to indicate the origin of ground-water mineralization. In theory, an increasing C/S ratio may suggest that horizontal flow of seawater (salt-water intrusion) may be the cause. A decreasing ratio may suggest that vertical flow from deep in the aquifer could be responsible. These effects may be the result of increased water withdrawal from the aquifer by pumping or by extended periods of low rainfall.

Iron – High iron concentrations in local wells likely indicate a deteriorating steel well casing, either in your well or in a nearby well that contaminates the aquifer locally. About half of the wells constructed in Sarasota County have steel casings, the other half have PVC casings.

TDS (Total Dissolved Solids) – Dissolved solids refer to any mineral, salt, metal, cation (positive electric charge particle) or anion (negative electric charge) dissolved in water. This includes anything present in water other than the pure water molecules and suspended solids. Suspended solids are particles or substances that are neither dissolved nor settled in the water, such as wood pulp. Waters with high dissolved solids are generally of inferior palatability. A TDS of less than 500 mg/L is desirable in drinking water.

Hardness – Water hardness is a measure of only the cation (cation = positive charge) dissolved in the water and is therefore, related to dissolved solids. The more cations dissolved in the water the "harder" the water. The most common cations of this type are calcium and magnesium. Hardness is usually reported as an equivalent amount of calcium carbonate (CaCO3). Generally, waters are classified according to degree of hardness as follows:

mg/L of calcium carbonate
Water hardness classification
 
Less than 75
Soft water
 
75 – 150
Moderately hard water
 
150 – 300
Hard water

Greater than 300
Very hard water
 
Hard water is objectionable because of the formation of scale in boilers, water heaters, radiators, and pipes with resultant decrease in the rate of flow and heat transfer as well as in increased corrosion. In addition to its effect on soap consumption, excessive hardness can shorten the wearing ability of fabrics and toughen cooked vegetables.

pH – This is a rough measure of the acidity of water. The pH of distilled water is 7, which is neutral. Water with a pH less than 7 is an acid and water with a pH above 7 is an alkali. Fluids in your stomach are pH 2 and those in your small intestine are pH 9. In general, the lower the pH, the higher the level of corrosion in pipes and fixtures will be. However, pH is only one of a variety of factors affecting corrosion. pH in drinking water is not a health issue unless it falls below 4 or above 10. The optimum pH is in the range 6.5 to 9.5.

Color – The color of your water can be indicative of specific problems as given below:

Green or blue water is usually caused by corrosion of copper plumbing. If corrosion is occurring, dripping water will leave a bluish-green stain on porcelain fixtures. Certain metals, such as copper, that get into drinking water from corrosion may pose a health concern. The problem could be in the home’s piping. If you suspect corrosion, contact a licensed plumber.

Black or dark brown water is usually due to manganese or pipe sediment and should clear up without further action when the sediment settles in the water main. Manganese does not pose a threat to human health. If it doesn’t clear after a few minutes of flushing your cold water faucets and toilets, wait about an hour and try again. If it still isn’t clear, contact your water utility.

Brown, red, orange or yellow water is usually caused by iron rust. Galvanized iron, steel or cast iron pipes can cause rusty water. While unpleasant and potentially damaging to clothes and fixtures, iron in drinking water is not a human health concern. If the iron is in the water from the well you may be able to eliminate it by filtration or chlorination. Controlling iron may require replacing old pipes inside the house.

Milky white or cloudy water is often caused by tiny air bubbles. If your water is white, fill a clear glass with water and set it on the counter. If the water starts to clear at the bottom of the glass first, the cloudy or white appearance is air and is not a health threat. It may be caused by high water pressure in the system or, more likely for kitchen faucets, by a loose or malfunctioning filter screen on the end of your faucet. Unscrew the end of the faucet, rinse the filter and replace. If your cloudy water does not clear after setting five minutes, you may have a bacterial contamination in your aerator. Pouring a cup of household bleach or pool chlorine in your aerator once a month should eliminate the cloudiness. The aerator should be cleaned out at least twice a year.