The Water Test Guide

By Melissa Rudy, Tests.com Contributing Writer

With the quality of public water constantly changing, water testing is essential to our health and well-being. Along with properly maintaining your well, regular testing is the only way to ensure the safety of the drinking water your family consumes.

By definition, water testing is the ongoing sampling of water from various sources and the analysis of its quality. Water sources can include rivers, lakes, groundwater, recirculated cooling streams, boiler feedwater or condensate, and process effluents. In addition to preserving a safe supply of public drinking water, regular testing also streamlines industrial processes to create better products and reduce costs.

Water testing equipment measures a variety of characteristics. Tests for bacteria and chemical compounds are available, as well as colorimeters, turbidimeters, and multiparameter meters for measuring pH, ORP, conductivity/salinity/total dissolved solids, dissolved oxygen, and temperature.

Water can be tested for hundreds of impurities and bacteria. Among the more common chemicals, elements and minerals are:

• Alkalinity
• Aluminum
• Chloride
• Chlorine Dioxide
• Color
• Copper
• Dissolved Organic Carbon
• Fluoride
• Free Chlorine Residual
• Hardness
• Iron
• Manganese
• Methane
• Odor
• Organic Nitrogen
• pH Balance
• Sulphate
• Sulphide
• Taste
• Temperature
• Total Dissolved Solids
• Turbidity
• Zinc

Water testing is carried out in states, provinces, and countries throughout the world, with some regions more conscientious than others. Some impoverished countries suffer from widespread health issues stemming from an absence of regulated testing processes.

Private water supplies should be tested every year for total coliform bacteria and nitrates. Depending on the type of well and the geographical location, additional tests may be required. Dugout and shallow wells (typically located on farms) are especially susceptible to pesticide contamination. Some groundwater sources can also contain elevated levels of arsenic.

The most common well water tests are bacteria tests and chemistry panels:

Bacteria tests are used to measure both the total coliform organisms and the more widely known E. coli. These tests provide an indication of the condition of the well and the attached plumbing system. Contamination by serious sources of bacteria, such as sewage and manure, is also discernable through this test. Private wells should be tested annually for bacteria, or more frequently if you notice significant changes in the water’s taste, odor, or appearance.

Chemistry tests measure some of the more common chemical constituents found in drinking water. Some of the 19 tested parameters are health-based, such as nitrate, sodium, and chloride. Affecting the aesthetic quality are pH, manganese, and iron; still more indicate the basic make up of water. Chemistry testing is recommended at the initial construction of the well and every several years after that.

Common Water Quality Problems

Chloride: A major component naturally found in water, Chloride is present in low concentrations in surface water. Ground water contains varying amounts of chloride depending on the location. Chloride is not generally harmful to most people, but at higher concentrations, the sodium it contains can be dangerous to those who suffer from heart or kidney disease. Most restrictions are based on palatability (taste) rather than safety.

Taste & Odor: Though neither of these characteristics poses a public health hazard, they are the most important characteristics of water. If public water smells or tastes bad, it will be virtually impossible to convince the public that it’s safe to drink. Both taste and odor are usually determined by naturally occurring organic matter in the water. Additional factors may include chemicals and other inorganic matter.

Fluoride: Naturally found in low concentrations, fluoride is derived from fluorite. The amount of fluoride content may vary based on water source and geographical location. In small quantities, it’s beneficial in preventing tooth decay, but excessive amounts result in the mottling of tooth enamel and increased brittleness.

Iron: Most water contains a small amount of iron, and concentrations under 0.3mg/L don’t pose any health hazard. Iron is colorless in fresh pumped water, but will turn yellow or brown in the presence of air. The presence of iron can discolor laundry, stain plumbing and dishes, and cause a slimy coating inside pipes. It can also give drinking water a bitter, harsh, or even sweet taste.

Lead: Natural lead concentration in water is quite low. In domestic water, lead levels increase the longer the water is left standing in the plumbing systems.

Manganese: With chemical properties similar to iron, manganese is found in reduced and oxidized states in ground water. Typically it’s only slightly soluble, but if a water reservoir is lacking in oxygen, it may leach the soils and bedrock, resulting in elevated levels of manganese.

Nitrate: This naturally occurring ion is an essential nutrient to all life forms. The main sources of nitrate present in groundwater are decaying plant or animal material, agriculture fertilizers, domestic sewage, and manure. High concentrations are found in communities with shallow wells and intense farm production with fertilization.

pH: pH values can range from 0 to 14. The lower the number, the more acidic; the higher the number, the more alkaline. Corrosion of pipes or well casings can occur when pH levels are below 6.5.

Sodium: All natural water contains sodium, which is a light alkali metal, chemically active, and not often found in its pure state. Most sodium compounds dissolve easily in water. Elevated sodium levels are often associated with sodium chloride from sea water or road salt.

Hardness: This characteristic refers to water’s ability to neutralize soap, or inability to form soap lather. Hard water is responsible for scale formation on pipes, boilers, and a variety of household appliances. It can cause a scum layer to form on tea and coffee, and can result in dinginess in clean laundry. A little-known fact is that hard water is actually better for drinking, since the calcium and magnesium content promotes tooth and bone strength.

Presence/Absence Tests:

Presence/Absence Test: Water samples are mixed with a unique medium and incubated. This process can take up to five days at temperatures between 26 and 35 degrees C. If contamination is present, the color will change from purple to yellow.

Hydrogen Sulphide Test: This test can indicate sever water contamination. A paper strip treated with a special chemical is incubated with a water sample between 25 and 35 degrees C. If hydrogen sulphide is present, the paper turns black to indicate a positive contamination.

Coliphage Detection Test: One of two tests used for monitoring recreational water, this analysis checks for the presence of coliphages, which are viruses that feed on fecal coliforms like Escherichia coli , more commonly known as E. Coli. This test may indicate that more serious problems are present, such as dangerous viruses, bacteria, and parasites that are transmitted by humans. Water samples are obtained and incubated overnight at temperatures between 25 and 35 degrees C. The water is sampled in Petri dishes with dried E. Coli. If the Petri dish has clear spots in the agar after 8 – 24 hours, this indicates that the E. Coli couldn’t grow because the sample is contaminated with fecal matter.

A-1 Broth Test: This reliable test requires precision and high incubation temperatures of 44.5 degrees C. Water samples are incubated for 24 hours in tubes that contain cultures. If fecal coliforms are present, they multiply and produce a gas that is visualized in the second tube that is inverted inside the first.

Basic Drinking and Household Use Suitability

Testing for Basic Water Potability measures the following traits:

Coliform Bacteria: Used to detect the presence of harmful microorganisms in water, coliform bacteria tests are vitally important to human health.

Nitrate: Though nitrate is a common contaminant in groundwater, high concentrations can be dangerous to infants under six months of age. Nitrate interferes with the body’s ability to carry oxygen throughout the bloodstream.

Sodium, Chloride and Manganese: These ionic minerals can affect the taste and odor of water.

Fluoride: Trace amounts of fluoride promote dental health, but excessive levels can deteriorate tooth enamel.

Sulphate: Large amounts of sulphate can irritate the gastrointestinal tract and cause an unpleasant taste in drinking water.

Iron: This inorganic substance is dissolved in water, but high levels can reduce its palatability.

If a water source is suspected to be contaminated, there may be indicators for further testing. Groundwater source parameters are measured for arsenic, selenium, and uranium, in addition to the standard pesticide tests applied to surface water.

It is recommended that private water supplies undergo basic tests at least once a year. Shallow wells and surface water sources should be tested much more often, as they are more susceptible to contamination.

Testing drinking water at the tap in addition to the source provides another layer of safety, helping to determine if your water treatment system is operating properly or if the quality of your water has changed.

There are many additional tests that can be performed on your water. Below is a sampling of these tests:

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Total Coliform (TC)

Contamination in a water supply can be indicated by the presence of total coliform bacteria. While the presence of total coliforms doesn’t always mean there’s a health risk, it does flag the need for further testing. The absence of coliforms usually means the water is free of pathogens and infections and is safe to drink.

Escherichia coli (EC/E.Coli)

One of the nastiest and most dangerous contaminants, E. Coli indicates the presence of fecal (human or animal) contamination. Steps should be taken immediately to disinfect the water and remove the source of contamination. If this isn’t possible, an alternate water source should be utilized until the water has been decontaminated. The use of contaminated water for even the simplest of activities, such as brushing your teeth, can pose significant health hazards.

Heterotrophic Plate Count (HPC)

Not typically part of standard water testing for homeowners, HPC testing can provide useful information about the microbiological quality of water. Although HPC bacteria aren’t normally indicators of disease, they can potentially contain pathogens. HPC can be used to measure changes during water treatment and distribution.

Colorimeters

This test measures the light absorbed by water after reacting with a reagent that produces the color change. The intensity of absorbed light is proportional to the concentration of the compound. Colorimeters are quite accurate in indicating the concentration of various compounds. Specific test kits are available for easy analysis, reducing chances of error.

Multiparameter Meters

These tests measure pH, ORP, conductivity/salinity/TDS, and/or DO/biological oxygen demand. Test kits allow you determine the concentration of specific chemical compounds in your samples. The easy-to-use tests contain prepared reagents and standards.

Colorimetric Test Kits

These tests measure the concentration of a substance in a water sample. The darker the color, the higher the concentration.

Titrimetric Test Kits

Water samples are treated with an indicator and a standard titrant is added until the reaction is completed, gauged by a color change. The amount of titrant corresponds to the concentration being tested.

Turbidimeters

In water, turbidity is caused by suspended and colloidal matter like clay, silt, and finely divided organic and inorganic substances. Plankton and other microscopic organisms may also play a role in determining turbidity. Samples should be measured by light scattered at a 90-degree angle to a light source. Measurements are displayed in nephelometric turbity units.

Water Quality Testing

Though no single measurement can ensure complete water quality, regular testing and early treatment can prevent many diseases and illnesses. Water quality is defined by analyzing:

• Chemical Content: A conglomeration of hardness, metals, nutrients, chloride, sodium, organic compounds, etc.

• Physical Content: Measures turbidity, color, odor, etc.

• Biological Content: Measures fecal coliform, total coliform, viruses, etc.

100% pure water (containing no minerals or chemicals) does not exist naturally. Safe drinking water retains naturally occurring minerals and chemicals like calcium, potassium, sodium, and fluoride. Although they’re beneficial to your health, these substances can give water a different taste. Quality drinking water, also known as potable water, is free from disease-causing organisms, harmful chemical substances, and radioactive matter. It tastes good and is aesthetically appealing, and is free from color and odor.

Recommended Testing Methods

Samples of water should be obtained using the following procedure:

• Pump water from the well for about 3 minutes. A nitrate strip should be submerged in the flow for one second, and then withdrawn and allowed to develop color for 60 seconds. Compare the color against the information included with the test kit. Do the same with a pH strip.

• Collecting a sample in a clean, clear glass vial or bottle, make visual observations about the turbidity, and then check for odors.

• Using the same sample, measure the TDS with a pocket TDS meter. Note the number in PPM by using an appropriate multiplier.

For accurate results, care should be used when obtaining bacteria test samples. Scorch the pump pipe briefly with a match to remove residual bacteria from the pipe or pump surface. Let the water flow for 2-3 minutes and then fill a plastic sterile sample bag.

Total Coliform testing is done by pouring the water in vials to the fill line. Be sure the lip of the vials and the inner surface of the cap don’t come into contact with anything, and put the caps on. After placing vials upright in the box, set them aside for 24 – 36 hours. Note color changes, gas formation, and position of thimble in each vial.

Aerobic and Sulphate-Reducing Bacteria Tests

These indicate the presence of bacteria that cause slime formation, turbidity, taste, odor, and corrosion. These tests are really just simple indicators; if problems are found, further tests should be carried out to determine the nature of the microbial issue.

Test Result Interpretation/Response

• Turbidity: If the water is cloudy, it is possible that contaminated surface run off could be entering the aquifer through cracks or other areas. While not dangerous, turbidity reduces the effectiveness of disinfection.

• Odor: Drinking water should never have an odor. The presence of an odor indicates that harmful substances may have entered your water source.

• Excessive TDS: Counts exceeding 500mg/L could indicate unsanitary water supplies.

• pH: Well water readings should range from 5.5 to 8.5. If readings are outside this range, the water quality can be difficult to correct.

• Nitrates: Concentrations above 10mg/L are known to cause blood disorders in infants. Manure, sewage, and nitrogen fertilizers can cause elevated levels in drinking water.

While it can be difficult to identify specific disease-producing organisms, water should be regularly tested. The presence of some indicators may indicate more serious health risks. If dangerous levels of bacteria are detected, a health professional should conduct more thorough testing.

Are you interested in a water test? Take a look at our Water Test Directory. For more information on water testing, read our interviews with water test expert Scott Bradley and Joshua K. Das.