Non-Health Issues

Non-Health Issues

Photo of Child in BathtubSecondary maximum contaminant level

Secondary Maximum Contaminant Levels are non-health related contaminants concentration limits for nuisance contaminants and physical problems. These standards are useful as guidelines, but are not enforced by regulatory agencies. ESS laboratories can test all the Secondary Maximum Contaminants.


Alkalinity represents the sum total of the bases in the water, and thus is the acid-neutralizing capacity of the water. It is due largely to the presence of calcium, magnesium and sodium carbonates and bicarbonates. Most natural drinking water has an alkalinity in the range of 10-500 mg/l. Alkalinity testing is used in combination with other tests for sizing the proper equipment.


Chloride in drinking water is associated with the salt content and sum of dissolved minerals in the water.  The EPA has set a secondary maximum contaminate level of 250 mg/l for chloride.  This limit is the concentration in water where most people with notice will notice a salty taste.


Fluoride is a naturally occurring mineral that helps protect teeth from tooth decay. Well water contains some naturally-occurring fluoride, but the levels are usually too low to prevent tooth decay. Many public water systems add fluoride to the water to an optimum level of 0.7 mg/l. Children may develop fluorosis if they take in too much fluoride while their teeth are still developing under the gums. Fluorosis develops over time and white spots may appear on the surface of the teeth.


Hardness is essentially a measure of the calcium and magnesium in water. Hard water is not a health risk; however, it keeps soap from lathering, decreases cleaning action of soaps and detergents, leaves soap “scum” on plumbing fixtures, and leaves scale deposits on water pipes and hot water heaters, possibly shortening the life of the heater. Softening treatment is recommended for very hard water (above 120 mg/l). Water with hardness of about 80 mg/l or less does not need softening. Water hardness may also be reported in units of grains per gallon, or gpg (1 gpg = 17.1 mg/l hardness).


Iron in water generally does not present a health risk. However, it can be objectionable if present in amounts greater than 0.3 mg/l. Excessive iron can leave brown-orange stains on plumbing fixtures and laundry. It may discolor the water and beverages made with the water, and give them a bitter metallic taste.


The presence of manganese in amounts greater than 0.05 mg/l may give water a bitter taste and produce black stains on laundry, cooking utensils, and plumbing fixtures. It generally does not present a health risk.


The pH of water indicates whether it is acidic or basic (alkaline). Acidic water can corrode pipes and may dissolve toxic metals such as copper and lead from the plumbing system, allowing them to enter the water. Water with a pH below 6.5 is acidic enough to consider treatment. Alkaline water with a pH above 8.5 is seldom found naturally, and may indicate contamination by alkaline industrial wastes. The EPA suggests a range of 6.8 to 7.2 for pH of drinking water. Outside levels of pH may cause greenish-blue staining.


Hydrogen sulfide is a gas that can be problematic in groundwater, resulting in the characteristic “rotten egg” odor. The gas is commonly generated by the action of bacteria in the decay of organic matter, but its presence does not necessarily indicate bacterial contamination of the water. Water containing this gas may also corrode iron and other metals in the water system, or stain plumbing fixtures and cooking utensils. It can be difficult to quantify the level of hydrogen sulfide in water due to its escape as a gas.

Total Dissolved Solids (TDS)

TDS represents the sum total of all of the substances that are in solution in the water. High concentrations of dissolved solids may cause adverse taste in water and may deteriorate household plumbing and appliances. The EPA has set a secondary maximum contaminant level of 500 mg/l for this parameter.

Actual equipment recommended is based on overall water test results. Please contact us ( or 540-825-2781) with any questions regarding which equipment may be right for your water problem.


EPA: U.S. Environmental Protection Agency
mg/1: Concentration unit of milligrams per liter of water, equivalent to parts per million (ppm)
µg/l: Concentration unit of micrograms per liter of water, equivalent to parts per billion (ppb)