Water glossary
Understand your water, term by term
Plain language definitions for the words you'll hear during testing, treatment and installation.
- 27 terms explained
- Bilingual glossary
- No jargon
What do water treatment terms like hard water and reverse osmosis actually mean?
They describe specific, measurable things about your water, and understanding them helps you make sense of your test results. Below you'll find plain language definitions for the terms Lucia Water Solutions uses most often.
Terms are listed alphabetically so you can jump straight to the word you heard.
If a term still isn't clear, ask about it during your free water test; explaining your results is part of the visit.
- 1,4-Dioxane
- 1,4-dioxane is an industrial solvent stabilizer that dissolves easily in water and is difficult to remove with standard filtration. It is a well documented issue in parts of Long Island's groundwater, and New York has proposed tightening its limit to 1.0 parts per billion, well below the older blanket standard of 50 parts per billion. Advanced treatment methods, rather than basic carbon filters, are typically needed to reduce it effectively.
- Activated Carbon
- Activated carbon is a highly porous material, often made from coconut shells or coal, that attracts and traps chlorine, certain organic chemicals, and odor causing compounds as water passes through it. It is one of the most common filter media used in whole house and under sink systems. Activated carbon is effective for taste and odor but does not remove hardness minerals or many dissolved metals on its own.
- Alkaline Water
- Alkaline water has a higher pH than standard tap water, usually achieved by adding beneficial minerals during or after reverse osmosis filtration. Some reverse osmosis systems include an alkaline stage specifically to rebalance the pH of the highly purified water the membrane produces. Alkaline enhancement is about taste and mineral content, not contaminant removal.
- Backwash
- Backwash is the automatic cleaning cycle that some water softeners and filters use to reverse the flow of water and flush trapped particles or spent resin out of the system. It typically happens on a set schedule, often overnight, and uses a set amount of water to keep the system performing at its best. Skipping backwash cycles can reduce a system's effectiveness over time.
- Brine Tank
- A brine tank is the separate tank attached to a water softener that holds a concentrated salt or potassium chloride solution used to recharge the resin bed during regeneration. Homeowners periodically add salt pellets or blocks to keep the tank at the right level. Running out of salt is one of the most common reasons a softener stops working properly.
- Chloramine
- Chloramine is a disinfectant formed by combining chlorine with ammonia, and some utilities use it instead of, or along with, chlorine to keep a longer lasting residual in the distribution system. It can be harder to remove than chlorine alone and typically requires a catalytic carbon filter rather than a standard carbon filter. Chloramine is also more likely to affect people on kidney dialysis and those who keep fish, so it deserves special attention when treating water.
- Chlorine
- A chemical disinfectant added to municipal water supplies to kill bacteria and other pathogens. While effective for disinfection, residual chlorine can affect taste and may form harmful byproducts.
- Filtration
- The process of passing water through a filter medium to remove suspended particles, contaminants, and impurities, improving water quality for drinking and household use.
- Grains Per Gallon (gpg)
- Grains per gallon, or gpg, is the standard unit used in the United States to describe water hardness, measuring the amount of dissolved calcium and magnesium in a gallon of water. One grain per gallon equals about 17.1 parts per million. Homeowners often see this number on a water softener's specification sheet to size the system correctly.
- Hard Water
- Water containing high concentrations of dissolved minerals, primarily calcium and magnesium. Hard water causes scale buildup in pipes and appliances and reduces soap effectiveness.
- Ion Exchange
- Ion exchange is the process most water softeners use to remove hardness minerals, swapping calcium and magnesium ions for sodium or potassium ions as water passes through a resin bed. Over time the resin becomes full and needs to be recharged with a saltwater brine solution. This is the technology behind traditional water softening.
- Iron and Manganese
- Iron and manganese are naturally occurring minerals found in some groundwater and well water, often traced to local bedrock and soil conditions. They can cause reddish brown or dark staining on fixtures, laundry, and plumbing, along with a metallic taste. Specialized filtration, rather than a standard softener, is usually needed to remove higher concentrations effectively.
- Micron
- A micron is a unit of measurement, one millionth of a meter, used to describe the size of particles a filter can capture. Lower micron ratings capture smaller particles, so a 1 micron filter removes finer sediment than a 20 micron filter. Filter housings are often labeled by micron rating to make it easy to match the right filter to the water quality issue.
- Nitrates
- Nitrates are compounds that occur naturally but can also enter groundwater from fertilizer, septic systems, and agricultural runoff, making them a more common concern for private wells than municipal supplies. High nitrate levels are a particular health concern for infants and pregnant women. A water test is the only reliable way to know whether nitrates are present in a well.
- Parts Per Million (ppm)
- Parts per million, or ppm, is a way of measuring very small concentrations, describing how many units of a substance exist for every one million units of water. It is commonly used to report hardness, total dissolved solids, and many contaminants in a water test. One ppm is roughly equivalent to one drop of a substance in a large bathtub of water.
- PFAS
- PFAS, or per and polyfluoroalkyl substances, are a large family of manufactured chemicals used for decades in nonstick, waterproof, and firefighting products that do not break down easily in the environment. New York limits PFOA and PFOS in public water to 10 parts per trillion each, and New Jersey's limits are 14 and 13 parts per trillion. Because they persist in soil and groundwater, PFAS can show up in both municipal supplies and private wells years after the original source is gone.
- PFOA
- PFOA, or perfluorooctanoic acid, is one of the most studied PFAS chemicals and was once widely used in nonstick cookware coatings and industrial manufacturing. New York's maximum contaminant level for PFOA in public water is 10 parts per trillion, and New Jersey's is 14 parts per trillion. Even at these low concentrations, ongoing exposure is a health concern, which is why testing matters.
- PFOS
- PFOS, or perfluorooctane sulfonate, is another common PFAS chemical historically used in firefighting foam and stain resistant coatings. It was the contaminant behind the City of Newburgh's Washington Lake shutdown, when levels reached 170 parts per trillion in 2013. New York's current limit for PFOS in public water is 10 parts per trillion, and New Jersey's is 13 parts per trillion.
- Reverse Osmosis
- A water purification process that uses a semi-permeable membrane to remove ions, molecules, and larger particles from drinking water, typically removing 95-99% of dissolved contaminants.
- Sediment Filter
- A sediment filter is typically the first stage in a whole house system, designed to physically trap sand, silt, rust particles, and other visible debris before water reaches finer filtration stages. It protects downstream equipment, like carbon filters and softeners, from clogging prematurely. Sediment filters are especially important for well water, which often carries more particulate matter than municipal supplies.
- TDS
- Total Dissolved Solids (TDS) measures the combined content of all dissolved substances in water, including minerals, salts, and organic matter, typically expressed in parts per million (ppm).
- Total Dissolved Solids
- A measurement of all dissolved substances in water including minerals, salts, metals, and organic matter. High TDS levels can affect taste, safety, and appliance longevity.
- Trihalomethanes (TTHM)
- Trihalomethanes, often written as TTHM, are disinfection byproducts formed when chlorine reacts with naturally occurring organic matter in water. They are commonly tracked as a group because several individual compounds, including chloroform, tend to appear together. Utilities monitor TTHM levels because long term exposure at high concentrations is a recognized health concern.
- UV Sterilization
- UV sterilization uses ultraviolet light to disable the DNA of bacteria, viruses, and other microorganisms as water passes through a treatment chamber, without adding any chemicals. It is often paired with a sediment or carbon filter, since UV light works best on water that is already clear. Many well water systems include UV treatment as an added layer of protection against biological contaminants.
- Water Softener
- A filtration system that removes calcium and magnesium minerals from hard water through an ion exchange process, replacing them with sodium or potassium ions to prevent scale buildup.
- Water Testing
- The process of analyzing water samples to determine the presence and concentration of various contaminants, minerals, and quality parameters to identify treatment needs.
- Well Water
- Groundwater accessed through a drilled or dug well, typically untreated by municipal systems and potentially containing elevated levels of minerals, bacteria, or other contaminants specific to local geology.
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