Name
Description
Relations to daily life
Links
Acidic drainage
Occurs when the resulting water is highly acidic (low pH), making the water toxic to aquatic life. It usually leaves a bright orange or yellow sludge on riverbeds.
In the industrial world, acidic drainage is extremely common. When someone pours acidic liquids into metal pipes, it is also considered as acidic drainage.
Alkalinity
Water alkalinity is the water's capacity to resist changes in pH and neutralize acids.
In plumbing and industrial systems, it acts as a primary buffer. If not properly balanced, alkalinity levels dictate whether water becomes severely corrosive to metal infrastructure or causes damaging scale buildup
Arid
Extremely dry without enough rainfall to support most plant life.
There are many arid areas in the world, and those areas receive very little moisture.
Arsenic
A toxic metalloid that may occur naturally in groundwater or result from mining and industrial activity.
Long-term exposure can cause serious health effects even when water appears clear.
Bacteria
Microscopic living organisms. Some examples of common bacteria include: Escherichia coli (E. coli), Vibrio cholerae (cholera), Salmonella typhi (typhoid fever), Campylobacter species
These can find their way into your water source through sewers, animal wastes, flooding, and poor sanitation.
Basic (alkaline) water
Water with a pH above 7, meaning it is alkaline rather than acidic. The higher the pH above 7, the more basic the water. Basicity reflects a lower concentration of hydrogen ions and is influenced by dissolved minerals and alkalinity.
Mildly basic water is common and usually harmless; many tap and mineral waters sit slightly above pH 7. Very high pH can give water a slippery feel or bitter taste and may contribute to scale buildup, while also reducing the corrosivity that low-pH water causes in pipes.
Calcium
A dissolved mineral that contributes to water hardness.
Calcium can contribute to white scale in kettles, faucets, heaters, and pipes.
Chemical disinfection
The process of applying chemical agents to objects to kill pathogenic microorganisms.
Bleach, alcohol, and hydrogen peroxide are commonly used when cleaning or disinfecting areas.
Chloride
A dissolved negatively charged ion commonly found in salts.
High concentrations may contribute to salty taste and may increase the corrosiveness of water under some conditions.
Chlorine
A chemical element widely used as a disinfectant in water treatment to kill or inactivate pathogens.
Added to municipal water to keep it microbiologically safe; the leftover amount is measured as free, total, and residual chlorine.
Cistern
An underground tank used for storing liquids and water.
They provide water for household appliances (toilets, clothing washer, etc.) as well as potable water (with proper filtration and purification).
Coliform (Total Coliform)
A broad group of bacteria found in soil, vegetation, surface water, and on skin, used as an indicator of possible treatment, storage, or distribution-system problems. Their presence does not by itself prove fecal contamination but signals that contamination could be entering the system.
Detection suggests that wastewater or other contamination may have reached the water source and not been fully treated. Coliforms occur naturally in many environments, so they are used as a warning sign.
Corrosion
The dissolving or breaking down of a material caused by a chemical reaction; for our purposes, corrosion typically refers to the break down of metal pipes or plumbing parts.
For drinking water systems, corrosion causes metals such as lead and copper to enter the water. These metals can cause water to have a rusty color, metallic taste, and unsafe levels of metal in drinking water.
E. coli (Escherichia coli)
A species of bacteria that is used as a more specific indicator of fecal contamination.
Detection in drinking water suggests contamination from human or animal waste and requires prompt investigation.
Fluoride
A dissolved ion that may occur naturally or be added under controlled drinking-water programs.
Appropriate concentrations may support dental health, while excessive long-term exposure can be harmful.
Free chlorine
The portion of chlorine available to continue disinfecting water
Test strips or meters may be used to determine whether disinfectant protection remains in a household tank or pipe system.
Groundwater
Water found beneath the ground in the small spaces and cracks between soil, sand, gravel, etc. Groundwater usually originates from rain and snow that penetrates into the ground over time.
Groundwater is especially important for homes that use wells as a source of water! Wells act similar to a straw, extracting ground water up to the surface. The quality of groundwater can be affected by nearby septic systems, farms using pesticides or fertilizers, factories causing industrial pollution, and even naturally occurring minerals.
Hardness
The concentration of dissolved calcium and magnesium in water.
Hard water may cause scale in kettles, water heaters, plumbing, and filter equipment.
Hydrocarbon
An organic chemical compound of hydrogen and carbon in the gaseous, liquid, or solid phase.
It is found in fossil fuels and serve as raw materials to create products like plastics, rubber, and synthetic fibers.
Intermittent water supply
A piped water service that delivers water for less than 24 hours a day rather than continuously. ('Intermittent' on its own means occasional or not continuous.)
Common in parts of South Asia, Latin America, Africa, and the Middle East, where it can worsen water quality and create health risks.
Ion exchange
A chemical process that removes ions.
Ion exchange is common in everyday items. It occurs when filtering tap water, removing impurities for sugar syrups, and electronics.
Iron
A metal that may occur naturally in groundwater or enter water through pipe corrosion.
It may cause reddish staining, sediment, discoloration, or metallic taste.
Lead
A metal that may occur naturally in groundwater or enter water through pipe corrosion.
It may cause reddish staining, sediment, discoloration, or metallic taste.
Magnesium
A dissolved mineral that contributes to water hardness.
Magnesium affects hardness, mineral taste, soap use, and scale formation.
Magnesium
A dissolved mineral that contributes to water hardness.
Magnesium affects hardness, mineral taste, soap use, and scale formation.
Manganese
A naturally occurring metal that may affect water color, taste, deposits, and staining.
It may cause dark stains in sinks, clothing, tanks, and plumbing fixtures.
mg/L (milligrams per liter)
The standard concentration unit for dissolved substances in water (mass of substance per liter). Used to report metals, chlorine residual, nitrate, and many other parameters.
For drinking water chlorine residual, the EPA recommends 0.2 to 4.0 mg/L. Lab reports for metals and other contaminants are commonly given in mg/L.
mg/L as CaCO3 (milligrams per liter as calcium carbonate)
A reporting convention that expresses hardness or alkalinity in terms of an equivalent amount of calcium carbonate, so different minerals can be compared on one scale.
When you get a water-hardness report or buy a water softener, the hardness is given this way, so a single number lets you compare your water to "soft" or "hard" thresholds.
mg/L as N (milligrams per liter as nitrogen)
A reporting convention that expresses only the nitrogen portion of nitrate or nitrite. A result reported as nitrate-nitrogen is numerically different from one reported as total nitrate.
Knowing whether a nitrate result is reported 'as N' or 'as nitrate' matters when comparing it to a health limit.
Microbiological confirmation
The laboratory process of identifying and verifying the presence of microorganisms in a sample.
Confirms whether a positive screening result (e.g., for coliform) truly indicates living target organisms before action is taken.
Microplastics
Tiny plastic particles (generally smaller than 5 mm) found in environmental and drinking water, originating from fragmented plastic waste rather than from the treatment process itself.
They may originate from packaging, bottles, synthetic textiles, wastewater, and degraded plastic waste. WHO considers the current health risk in drinking water to be low but based on limited evidence, so research is ongoing.
Mineralization
The process of breaking down organic matter into basic, inorganic minerals.
In nature, mineralization recycles nutrients; in water it influences how many dissolved minerals end up present. Examples: Calcium, Magnesium, Potassium, Sodium, Iron, Floride, Zinc.
MPN/100 mL and CFU/100 mL
Two ways of reporting how many microorganisms were found in a 100 mL sample. CFU (colony-forming units) counts colonies grown on a plate; MPN (most probable number) is a statistical estimate. Used for total coliform and E. coli.
If you send well or tap water to a lab for a safety test, this is the count format you'll see on the results. A higher number per 100 mL means more bacteria were found.
Nitrate
A dissolved nitrogen-containing ion associated with fertilizers, animal waste, sewage, septic systems, and some natural deposits.
High nitrate concentrations are particularly dangerous for infants and are important in agricultural and well-water areas.
Nitrite
A dissolved nitrogen-containing ion related to nitrate and biological nitrogen conversion.
High concentrations may interfere with the blood’s ability to carry oxygen, especially in infants.
NTU/UNT
The standard unit commonly used to report turbidity.
A turbidity meter may display results such as 1 NTU or 5 NTU.
Parts per million
A concentration unit abbreviated ppm. In dilute water, 1 ppm is often approximately equal to 1 mg/L.
Household TDS and chlorine meters commonly display readings in ppm.
pH
Used as a universal metric to describe the acidity or basicity of a solution. Formula: pH = -log[H+]
Unusual pH can contribute to pipe corrosion, metallic taste, mineral deposits, or reduced treatment effectiveness.
pH strip
A color-changing paper or plastic strip used to test the pH level of a liquid.
It is used across many fields: science, water bodies, health, food, beverage, etc.
Presence or absence in 100 milliliters
A binary (T/F) method of reporting whether an indicator organism was detected in a 100 mL sample.
Many simple drinking-water bacteria tests give a simple safe/unsafe style answer. "Present" means bacteria were detected and the water needs attention, "absent" means none were found in the sample.
Residual chlorine
Chlorine-based disinfectant remaining in water after the initial treatment process.
It helps protect water from microbial growth/regrowth while the water travels through pipes or remains in storage
Reverse osmosis
A process that forces water through a semi-permeable membrane under pressure, leaving contaminants behind.
It is used to transform tap water into potable water.
Saline drainage
Occurs when water is carrying high concentrations of dissolved salts and metals from broken-up rock.
Affects irrigation and downstream water quality in arid and agricultural regions.
Salinity
Measure of dissolved salts in water.
Salinity is involved in food, preservation, personal hygiene products, pools, and much more.
Salts
Compounds formed from positively and negatively charged ions (such as sodium and chloride) that dissolve in water and contribute to TDS and salinity.
Dissolved salts affect taste, hardness, and corrosivity, and are what salinity and TDS measurements capture.
Sulfate
A dissolved ion that may occur naturally in rocks, groundwater, or industrial discharges.
Elevated concentrations may affect taste and may have a laxative effect in people who are not accustomed to the water.
Surface water
Water found on top of the land such as rivers, lakes, ponds, wetlands, etc. Surface water is part of the water cycle and is often replaced by rain, runoff, and melted snow.
Surface water is often used for irrigation, fishing, recreation (swimming), and as a habitat for wildlife. Since surface water is exposed to the outside world, it can be easily impacted by contaminants such as trash, bacteria, sediment, fertilizers, etc. A lake near a farm, for example, can be affected by agricultural runoff.
Suspended particles
Solid or liquid particles that float within a fluid without dissolving.
The visible cloudiness or floating bits in unsettled water, like the sediment stirred up in a puddle. Doesn't dissolved and will slowly settle if the water sits still.
TDS meter
A digital device used to measure the total dissolved solids in a liquid.
It is often used to check the purity of tap water.
Total Chlorine
The combined amount of free chlorine and chemically combined chlorine in water.
A water-testing device may report both free chlorine and total chlorine. Additionally, pool chemicals are generally managed by the Total Chlorine metric.
Total dissolved solids
The combined amount of dissolved minerals, salts, and ions in water. commonly abbreviated TDS.
High TDS may cause salty or mineral taste, scaling, and deposits, but it does not identify individual contaminants.
Turbidity
The cloudiness or haziness of water caused by suspended particles, reported in NTU.
Visibly cloudy tap water is high-turbidity water; treatment plants monitor it closely because cloudiness can shield microbes from disinfection.
Turbidity meter
An instrument used to measure the cloudiness of a liquid.
It is used to observe water quality.
Ultraviolet (UV) disinfection
A process that uses short-wavelength UV-C light to inactivate microorganisms like bacteria, viruses, and mold.
It helps purify drinking water and wastewater.
Valve
A mechanical device used to control the flow of fluids within a system.
Valves are used in pipes, engines, and plumbing systems to start, stop, or regulate flow.
Virus
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism
Usually come from human sewage contamination. Some examples of viruses include: Norovirus Rotavirus Hepatitis A virus Enteroviruses
VOCs (Volatile Organic Compound)
A Carbon-based chemicals that easily evaporate into the air at room temperature.
They are found in many household and commercial products, including paints, perfumes, cosmetics, gasoline, etc.