Water Treatment Glossary:
Simple Definitions for Homeowners
Water treatment can feel technical, but it doesn’t have to be. This glossary explains the most common terms you’ll see when researching water systems in Ontario — in simple, homeowner‑friendly language.
Water Quality Terms
Water Hardness
Hardness is dissolved calcium and magnesium in your water which comes from groundwater as it travels through the rock formations underground. Hard water causes scale buildup, soap scum, and wreaks havoc on appliances.
Related: Water SoftenersSoft Water
Soft water is water that has had the hardness minerals, calcium and magnesium, removed, usually by a water softener. Soft water lathers better with soap, leaves no scale or spots behind, and is much gentler on your skin, hair, and appliances.
Related: Water SoftenersSodium
Sodium is added to your water in small amounts during the softening process, as it replaces the calcium and magnesium that cause hardness. For most people this amount is very minor, but anyone on a sodium-restricted diet can use potassium chloride in the softener instead, or add a reverse osmosis system for their drinking water.
Related: Water SoftenersIron
Iron can be present, primarily in rural properties that have a well. This mineral causes orange staining, a metallic taste/smell, and change the water to a yellow-brown colour.
Related: Rural Water TreatmentMagnesium
Magnesium is one of the two minerals, alongside calcium, that make your water hard. As water moves through underground rock it picks up magnesium, which then contributes to scale buildup and all the other headaches of hard water.
Related: Water SoftenersCalcium
Calcium is the most common mineral behind hard water. It's what leaves chalky white scale on your fixtures, inside your water heater, and throughout your plumbing, and it's the reason soap and detergent don't work as well as they should.
Related: Water SoftenersTannins
Tannins are naturally occurring organic compounds found in well water that cause yellow or tea-coloured water.
Related: Rural Water TreatmentChlorine
Municipal water treatment facilities add this disinfectant into the water to protect people from bacteria. Once chlorine has sanitized the water, the leftover chemical makes drinking water taste awful. Chlorine also damages rubber seals in appliances and can cause itchy dry skin.
Related: DechlorinationChloramine
Cities like Kitchener, Waterloo, Cambridge, and Brantford use chloramine to treat their water. This is a blend of chlorine and ammonia which enables the chlorine to last longer through the distribution process. It's important to know the difference because this chemical blend is much harder to remove than chlorine on its own. Chloramine also still has all the same effects as chlorine.
Related: DechlorinationSediment
Sediment is found in both city and well water. Sediment is any natural erosion such as sand, silt, or soil that cause cloudiness in the water. Sediment can also get inside the gearing of your appliances and clog up your pipes if they are not protected by filters.
Related: Whole-Home FiltersScale
Scale is the hard, chalky white buildup left behind when hard water is heated or dries up. You'll see it on faucets, in kettles, and inside water heaters and pipes, where it slowly reduces efficiency and shortens the lifespan of your appliances.
Related: Water SoftenersSulfur / Hydrogen Sulfide
Hydrogen sulfide is the gas responsible for the rotten egg smell in some well water. Even in small amounts it can make water unpleasant to drink and shower in, and it can tarnish silverware and fixtures. It's one of the most common complaints we hear from rural customers.
Related: Rural Water TreatmentManganese
Manganese is a mineral that often shows up alongside iron in well water. While iron leaves orange staining, manganese causes darker black or brown stains on fixtures, laundry, and inside toilet tanks. It is usually treated together with iron.
Related: Rural Water TreatmentpH / Acidic Water
pH measures how acidic or alkaline your water is on a scale from 0 to 14, where 7 is neutral. Acidic well water, meaning a pH below 7, can slowly corrode copper pipes and leave blue-green staining on fixtures. Raising the pH protects your plumbing.
Related: Rural Water TreatmentNitrates
Nitrates are contaminants that can seep into well water from fertilizer, septic systems, and farm runoff. Because they cannot be seen, smelled, or tasted, testing is the only way to catch them. A reverse osmosis system is one of the most effective ways to remove nitrates from drinking water.
Related: Drinking Water SystemsLead
Lead is a metal that can leach into drinking water from older pipes, solder, and plumbing fixtures, rather than from the source water itself. Because it builds up in the body over time, there is no safe level, especially for children and pregnant women. A reverse osmosis system is one of the most reliable ways to remove lead right at the tap.
Related: Drinking Water SystemsArsenic
Arsenic is a naturally occurring element that can dissolve into well water from the surrounding rock and soil. It has no taste, colour, or smell, so testing is the only way to detect it, and long-term exposure is a real health concern. Reverse osmosis is a common and effective way to remove arsenic from drinking water.
Related: Drinking Water SystemsFluoride
Fluoride is a mineral that some municipalities add to drinking water to help prevent tooth decay, and it can also occur naturally in some sources. While it is added for dental health, certain households prefer to remove it from their drinking water. A reverse osmosis system reduces fluoride along with other dissolved contaminants.
Related: Drinking Water SystemsPFAS / PFOA / PFOS
PFAS are a large group of man-made chemicals, sometimes called forever chemicals, used in products like non-stick coatings, food packaging, and firefighting foam. PFOA and PFOS are two of the most common types. They break down very slowly and can build up in water supplies over time. Reverse osmosis is one of the most effective ways to reduce PFAS in drinking water.
Related: Drinking Water SystemsRural/Well Water
Well water is drawn from an underground aquifer on your own property rather than supplied by the city. Because it isn't centrally treated or tested, its hardness, iron, sulphur, and bacteria levels can vary a lot from one property to the next, which is why well water often needs a customized treatment setup.
Related: Rural Water TreatmentCity Water
City water is supplied and treated by your municipality, tested to meet provincial and federal drinking water standards before it reaches your tap. It's already disinfected with chlorine or chloramine, but it still carries hardness and that leftover disinfectant taste and smell.
Related: DechlorinationTotal Dissolved Solids (TDS)
Total Dissolved Solids (TDS) is a measure of everything dissolved in your water, including minerals, salts, and metals, usually given in parts per million (ppm). A higher TDS reading means there is more dissolved material in the water. It's one of the main things a reverse osmosis system brings down, which is why RO water tastes so clean.
Related: Drinking Water SystemsWater Treatment Systems
Water Softener
Water softeners remove hardness in your home by swapping out the calcium and magnesium ions for sodium. Soft water can only be achieved by using salt for that ion exchange. Soft water means no scale buildup, softer skin and hair, cleaner and brighter laundry, and longer lasting appliances.
Related: Water SoftenersReverse Osmosis (RO)
Reverse osmosis water goes through a semi-permeable membrane and traps contaminants in the water so that all that is left is completely purified water. Depending on the strength of the membrane, 99% of contaminants are removed and the total dissolved solids (TDS) are greatly reduced. A reverse osmosis system is a convenient way to get purified water in your home.
Related: Drinking Water SystemsIron Filter
Iron filters are large filters that use air injection to separate the iron from well water. Then the leftover iron is trapped inside the tank and cleans it out in a backwashing cycle. This ensures that there is no discolouration or odor in the household. Iron treatment is not necessary for the majority of households in the city since iron treatment is taken care of by most municipalities.
Related: Rural Water TreatmentUV System
An ultraviolet (UV) system is a chemical-free way to disinfect bacteria from rural well water. It uses ultraviolet light to render bacteria inert, basically causing the bacteria to become inactive. It can clean water of not just bacteria, but also viruses. UV treatment is not necessary for households on city water since all bacteria is killed off by the chlorine or chloramine provided by the city.
Related: Rural Water TreatmentWhole-Home Filtration
Whole-home filtration treats all the water entering your house at one point, rather than just a single tap. Depending on your water, this can include removing chlorine or chloramine, sediment, or other contaminants, so every faucet, shower, and appliance gets cleaner water.
Related: Whole-Home FiltersDechlorinator
A dechlorinator is a whole-home filter that removes chlorine, along with its taste, smell, and drying effects, from your city water. Most municipalities in our area actually use chloramine rather than plain chlorine, so an effective system needs catalytic carbon media to remove it properly.
Related: DechlorinationDechloraminator
A dechloraminator is built specifically to remove chloramine, the blend of chlorine and ammonia that many cities now use. Because chloramine is tougher to remove than chlorine on its own, these systems rely on catalytic carbon media designed for the job.
Related: DechlorinationTechnical Terms
Ion Exchange
Ion exchange is the process at the heart of a water softener. As hard water passes through the softener's resin, the calcium and magnesium ions are swapped out for sodium ions. This swap is what actually removes the hardness from your water.
Related: Water SoftenersRegeneration
Regeneration refers to the cleaning cycle in a water softener where the system flushes out the hardness minerals that it has collected over time. Regeneration might be set for early hours in the morning while people are asleep, or with a dual tank system it will regenerate on demand. It is not recommended to force a regeneration; the water softener will automatically do that on its own.
Backwash / Backwashing
Backwashing is a self-cleaning cycle where a system reverses the flow of water through its tank to flush out the iron, sediment, or other material it has trapped. Iron filters and some other systems backwash automatically to keep the media clean and working properly.
Related: Rural Water TreatmentResin
Resin is the media inside a water softener, made up of thousands of tiny beads that hold sodium ions. As hard water passes through, the resin grabs the calcium and magnesium and releases sodium in their place. Over time the resin is recharged during regeneration.
Related: Water SoftenersFlow Rate
The amount of water that can move through a system at once. It's important for a water specialist to know the flow rate in a house so that they can properly size the equipment.
Grains Per Gallon (GPG)
Grains per gallon (GPG) is the unit used to measure water hardness. The higher the number, the harder your water. Knowing your GPG helps a water specialist size a softener correctly and set how often it should regenerate.
Related: Water SoftenersMicron Rating
A measurement of how fine a filter is, lower numbers mean finer filtration. Depending on the equipment that the filter is in front of, different microns could be used. For instance, a 5 micron filter should be in front of a UV light, but only a 20 micron filter is needed in front of a water softener.
Brine Tank or Salt Tank
The tank where salt is put in a water softener. This should always be halfway full of salt. We recommend using a hard pellet salt, so it doesn't cause issues with the water softener. There will be a few inches of water on the bottom of the salt tank, but you do not need to add any water, the water softener will do that on its own.
Media Bed
There are different types of media for different water treatment systems, but all of them are referred to as media beds. This would be resin in a water softener or carbon in a dechlorinator.
Catalytic Carbon
Catalytic carbon is a specialized filter media designed to remove chloramine, not just chlorine. Regular carbon can handle chlorine on its own, but chloramine is tougher to break down, which is why systems built for our local water use catalytic carbon instead.
Related: DechlorinationNeed Help Understanding Your Water?
If you’re unsure which system is right for your home, we can help you test your water and recommend the best solution.