Ammonia is a colorless, pungent gaseous compound, extremely soluble in water. It is a biologically active compound found in most waters as a normal biological degradation product of nitrogenous organic matter. It also may find its way to ground and surface waters through discharge of industrial process wastes containing ammonia and fertilizers. Ammonia can cause toxicity to aquatic animals and high levels of it can potentially kill aquatic organisms. Various methods can be used for the determination of ammonia in water, but the most common and cheapest among of it is the ammonia-selective electrode method.
Biochemical Oxygen Demand (BOD) is a measurement of the amount of dissolved oxygen (DO) that is used by aerobic microorganisms when decomposing organic matter in water. Like COD, it is an important water quality parameter because it provides an index to assess the effect discharged wastewater will have on the receiving environment. The higher the BOD value, the greater the amount of organic matter for oxygen consuming bacteria, and thus higher rate of dissolved oxygen consumption. Depletion of DO causes stress on aquatic organisms, making the environment unsuitable for life. BOD is also used extensively for wastewater treatment and is a common gauge to determine the design of the water treatment facility. The most common technique used for the determination of BOD, is the 5-day incubation BOD test and azide modification method.
Chemical Oxygen Demand (COD) is a measurement of the oxygen required to oxidize soluble and particulate organic matter in water. It is an important water quality parameter that provides an index to assess the effects of discharged wastewater on the receiving environment. Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen levels. Thus, it will be harmful to aquatic life. COD can be determined by various method such as closed reflux digestion, by titrimetric method.
Chlorides are salts resulting from the combination of the gas chlorine with a metal. Chlorine alone as Cl 2 is highly toxic and it is often used as a disinfectant. In combination with a metal such as sodium it becomes essential for life. Small amounts of chlorides are required for normal cell functions in plant and animal life. But excessive amounts of chlorides can also be harmful, such that it can corrode metals and affect the taste of food products. It can also contaminate freshwater streams and lakes. Some aquatic animals cannot survive in high levels of chlorides. By using chloride-selective electrode meters, concentrations of chlorides can already be measured accurately.
The presence of dissolved natural organic material, usually from aquatic humic matter, causes water to have color. Certain industries rely to the aesthetic appearance of water suitable for their industrial applications. Color may also affect photosynthetic processes of some underwater plants and algae which may interfere sunlight to pass through. The standard method for color of water is the platinum-cobalt method.
Cyanide is a carbon-nitrogen chemical unit which combines with many organic and inorganic compounds. It is an extremely toxic substance that is produced naturally and artificially. Cyanides are generally not persistent when released to water or soil, and are not likely to accumulate in aquatic life. But high levels of cyanides can cause rapid toxicity among aquatic life. One of the easiest and cheapest method available for the determination of cyanide concentration is the cyanide-selective electrode method.
Dissolved Oxygen (DO) refers to the level of free, non-compound oxygen present in water or other liquids. Oxygen is perhaps the most well-established indicator of water quality. It is an important parameter in assessing water quality because of its influence on the organisms living within a body of water. A dissolved oxygen level that is too high or too low can harm aquatic life and affect water quality. DO can be measured through classical method of azide modification or by membrane-electrode DO meters.
Fluorine is a natural trace element and exists in almost all soils. Fluoride is classified as any binary compound of fluorine with another element. Perhaps the most widely known use of fluoride is its addition to public drinking water supplies at about one milligram per liter (mg/L) of a fluoride salt, measured as fluoride, for the purpose of reducing tooth decay.
Nitrates are a form of naturally occurring nitrogen compounds found in several different forms in aquatic ecosystems. Nitrates are essential plant nutrients but can cause significant water quality problems in excess amount. It can accelerate eutrophication, causing dramatic increases in aquatic plant growth and thus, affects dissolved oxygen, temperature, and other indicators. Nitrate can be measured by nitrate-selective electrode meters.
Oil and grease is defined as any material recovered as a substance soluble in extracting solvent. It can be composed of fatty matter from animal and vegetable sources and from hydrocarbons of petroleum origin. Oil and grease in water can cause surface films and shoreline deposits leading to environmental degradation, and can induce human health risks when discharged in surface or ground waters. Presence of excessive amounts may interfere with aerobic and anaerobic biological processes and lead to decreased wastewater treatment efficiency. Liquid-liquid partition by solvent extraction is the most widely used method for the determination of oil and grease.
About pH pH is a measure of how acidic or basic water is. Its technical and scientific definition is that it is a measure of the activity of the hydrogen ion (H + ). The pH of water is a very important measurement parameter concerning water quality. It affects aquatic life wherein some creatures can only live at a usual pH range. It can also affect the solubility and toxicity of chemicals and heavy metals in the water. pH can be measured using a potentiometric instrument such as pH meter.
Phosphorus occurs in natural water and wastewater almost solely as phosphates. It is a common constituent of agricultural fertilizers, manure, and organic wastes in sewage and industrial effluent. It is an essential element for the growth of plants and animals and in lake ecosystems. But excessive amount of phosphorus in water can lead to eutrophication resulting in reduced stability of the ecosystem. Phosphorus concentrations can be measured by colorimetric determination by stannous chloride method or ascorbic acid reduction method.
Comes from the word surface active agent. They are amphiphilic molecules and are thus absorbed in the air-water interface. At the interface, they align themselves so that the hydrophobic part is in the air and hydrophilic part is in water. This will cause the decrease in surface or interfacial tensions.

Temperature is a key parameter in checking water quality. It affects the dissolved oxygen levels in water, the rate of photosynthesis, as well as metabolic rates of organisms. Each species of organism thrives in a specific temperature range. Some organisms use temperature as an indicator for reproduction and migration. Abnormality in water temperature can disrupt the balance of aquatic ecosystems with devastating effect.

Total suspended solids (TSS) are particles that are larger than 2 microns found in the water column. Most suspended solids are made up of inorganic materials, although bacteria and algae can also contribute to the total solids concentration. TSS is also a significant factor in observing the aesthetics of the water, as the more suspended solids that are present the less clear the water will become. Excessive suspended solids can because for concern for aquatic and human life as well as impede navigation and increase flooding risks. TSS can be measured through gravimetric determination.

Heterotrophs are a group of microorganisms that use organic carbon sources to grow and can be found in all types of water. Heterotrophic plate count (HPC) is a method that measures colony formation on culture media of heterotrophic bacteria in drinking water. Thus, the HPC test can be used to measure the overall bacteriological quality of drinking water systems. High levels of microbial growth can affect the taste and odor of drinking water. To determine HPC, pour plate method can be used as a method.

Total coliform bacteria are commonly found in the environment and are generally harmless while fecal coliform bacteria are a sub-group of total coliform bacteria. The presence of fecal coliform in a drinking water sample often indicates recent fecal contamination, meaning that there is a greater risk that pathogens are present than if only total coliform bacteria is detected. The presence of fecal contamination in aquatic environments is an indicator that a potential health risk exists for individuals exposed to this water. Multiple tube fermentation technique is often used for the determination of total and fecal coliforms.

Acidity is a measure of a solution’s capacity to react with a strong base (ex. NaOH) to a predetermined pH value. Acidity levels are measured in wastewater because it can be responsible for corrosive properties and can take a leading role in regulating biological processes as well as in chemical reactions.
Alkalinity is a measure of the acid-neutralizing capacity of water and is measured by titrating the solution with an acid (ex. H2SO4) until it reaches a known endpoint wherein its pH changes abruptly. Alkalinity of wastewater is measured as it affects biological processes and chemical reactions.
Turbidity is the cloudiness or haziness of a fluid which is a measure of water quality. It is a reduction in water clarity/transparency due to the presence of suspended particulates. This is usually measured to determine the optical property of solutions as it causes light to be scattered and absorbed rather than transmitted in straight lines through a sample.
Water hardness is the sum of the calcium and magnesium concentrations in the water. Hard water is high in dissolved minerals, largely calcium and magnesium. Water hardness is expressed as mg/L hardness as calcium carbonate. It is usually measured in industries because water hardness affects chemical reactions, industrial processes, and health considerations (for drinking water).