Common water quality terms

Rural water quality information tool

Online tool to assess quality and suitability of raw water sources for privately owned and operated supplies.

Aesthetic Objective (AO) - levels of substances or characteristics of water that can affect its acceptance by consumers, cause problems with water distribution systems and fixtures, or interfere with practices for supplying good quality water. They are not health related guidelines but are related to aesthetic aspects of the water.

Alkalinity - is not a specific substance but rather a combined effect of several substances. It is a measure of the resistance of water to a change in pH. The alkalinity of most prairie waters is in the range of 100 to 500 mg/L, which is considered acceptable. Water with higher levels is often used. Alkalinity is a factor in corrosion or scale deposition and may affect some livestock when over 1,000 mg/L.

Calcium and Magnesium - are elements of "hardness" in water. They are not hazardous to health but are undesirable because they may cause problems for domestic uses such as washing, bathing and laundering. It causes encrustations in kettles, coffee makers, and water heaters. It can also foul some water treatment systems such as distillers and reverse osmosis units.

Coliforms, Fecal - Fecal Coliforms are a general indicator of contamination from an animal or human source. Its presence in water indicates that the water has been contaminated by faeces of humans or other animals and the possible presence of intestinal disease-causing bacteria. They are a more general indicator than E. Coli. Fecal Coliforms are also useful indicators of the possible presence of viruses and protozoa.

E. Coli (Escherichia coli) - E. coli is a member of the total coliform group of bacteria and is the only member that is found exclusively in the faeces of humans and other animals. Its presence in water may indicate not only recent faecal contamination of the water but also the possible presence of intestinal disease-causing bacteria.

Coliforms, Total - The presence of these bacteria may indicate contamination in a water supply. This group of bacteria is found in feces, soil, and vegetation and is used as an indicator of the bacteriological quality of water. Coliforms are useful indicators of the possible presence of pathogenic bacteria and viruses.

Conductivity (E.C.) - is measured in decisiemens/meter (dS/m). It can be used to estimate the total dissolved solids in the water. Multiplying the conductivity in dS/m by 640 will give a good approximation of the total dissolved solids in mg/L. Conductivity tests are often used to assess water suitability for irrigation. Conductivity is sometimes expressed as microSiemens/cm (µS/cm OR uS/cm), which is 1000 times smaller as a unit than decisiemens per centimetre. (For example: 0.75 decisiemens/m=750 microsiemens/cm=0.750 millisiemens/cm). We have used the letter "u" within our tool to represent the "micro" prefix "µ". We have used the conversion of 1dS/m = 700 mg/L TDS within the tool because the federal guidelines have used this conversion for their guideline values for TDS.

Fluoride - occurs naturally in most groundwater wells and can help prevent dental cavities. As fluoride levels increase above the guideline, there is an increase in the tendency to cause tooth mottling.

Hardness - causes excessive soap consumption and scaling. Hardness is caused primarily by calcium and magnesium, but is expressed in terms of an equivalent of calcium carbonate. Hard water causes soap curd, which makes bathroom fixtures difficult to keep clean and causes greying of laundry. Hard water will also tend to form scale in hot water tanks, kettles, piping systems, etc. It can also foul some water treatment systems such as distillers and reverse osmosis units.

Iron - levels as low as 0.2 to 0.3 mg/L will usually cause the staining of laundry and plumbing fixtures. The presence of iron bacteria in water supplies will often cause these symptoms at even lower levels. Iron gives water a metallic taste that may be objectionable to some at 1 to 2 mg/L. Most water contains less than 5 mg/L iron, but occasionally, levels over 30 mg/L are found.

Maximum Acceptable Concentration (MAC) - level of a substance that is known, or suspected to, cause adverse effects on health.

NO3 nitrogen (Nitrate) - higher levels are often an indicator of contamination by human or livestock wastes, excessive fertilization or seepage from dump sites. The maximum acceptable concentration in drinking water is 10 mg/L. This figure is based on the potential for nitrate poisoning of infants. Adults can tolerate higher levels, but high nitrate levels may cause irritation of the stomach and bladder. The suggested maximum for livestock use is 100 mg/L.

Nitrate is converted to nitrite in the body. Nitrite causes asphyxiation by entering the bloodstream and reacting with hemoglobin (the red, oxygen-carrying pigment of the blood) to form methemoglobin, which is not able to carry oxygen to the body's tissue. Nitrate in water is approximately 10 times more soluble than in feed. Caution is needed to differentiate between nitrate and nitrate-N or nitrate as N (where only the amount of nitrogen occurring in the Nitrate is reported). Nitrate = Nitrate-N * 4.4. Nitrates can also occur naturally in groundwater at lower levels.

NO2 nitrogen (Nitrite) - has an element of toxicity. If sampled correctly, nitrite is usually an indicator of direct contamination by sewage or manure because nitrites are unstable and can quickly be transformed into nitrates suggesting that a current and ongoing source of fecal contamination is present. Nitrates and nitrites are considered together in water analysis interpretation. The conversion of the nitrogen ion as compared to the nitrogen component within the nitrite ion (Nitrite-N) is approximately Nitrite = Nitrite-N * 3.28.

pH - expresses the intensity of the acid or alkaline condition of a solution. A pH of 7 indicates neutral conditions on a scale of 0 (acidic) to 14 (alkaline). The generally accepted range for pH in water is 6.5 to 8.5 with an upper limit of 9.5.

Sodium - is not considered a toxic metal. 5,000 to 10,000 milligrams per day are consumed by normal healthy adults without adverse effects. The average intake of sodium from water is usually only a fraction of that consumed in a normal diet. People suffering from certain medical conditions such as hypertension may require a sodium restricted diet, in which case the intake of sodium from drinking water could be significant. Sodium is a significant factor in assessing water for irrigation and plant watering. High sodium levels affect soil structure and a plant's ability to take up water.

Sulphate (SO4) - concentrations over 500 mg/L can be a laxative to some humans and livestock. Sulphate levels over 500 mg/L may be a concern for livestock receiving marginal intakes of certain trace minerals. Very high levels of sulphates have been associated with some brain disorders in cattle and pigs.

Total Dissolved Solids (TDS) - comprise inorganic salts and small amounts of organic matter that are dissolved in water. The principal constituents are usually the cations calcium, magnesium, and sodium, and the anions carbonate, bicarbonate, sulphate, chloride, and nitrate.

Turbidity - is a measurement of particles of matter suspended in water. These particles can be clay, silt, finely divided organic and inorganic matter, plankton and other microscopic organisms. Turbidity is a measurement of how light scatters when it is aimed at water and bounces off the suspended particles. It is not a measurement of the particles themselves. In general terms, the cloudier the water, the more the light scatters and the higher the turbidity. The treated water turbidity target is 0.1 NTU (nephelometric turbidity units). Turbidity as a secondary indicator of suspended solids and is a common measurement made in surface water. It is used to determine the likely effectiveness of some disinfection processes such as ultraviolet light or chlorination that require direct exposure to the target contaminant..