Water filters: which type fits your home, and do you need one
Health Canada says drinking water that meets the Canadian guidelines does not usually need more treatment for health reasons.[1] So a filter is either a choice, for taste or appearance, or a fix for a specific problem a test has found, such as lead from a home’s own plumbing or a well result. If you buy one, Health Canada strongly recommends a filter certified to the standard for what you want it to do.
On this page
Which filter for which concern
| Your concern | Type of filter | Certification to look for | Read more |
|---|---|---|---|
| Taste or odour | Activated carbon | NSF/ANSI 42 (aesthetic effects) | |
| Lead | A filter certified for lead reduction | NSF/ANSI 53, with lead listed | Water filters for lead |
| PFAS | Activated carbon, reverse osmosis at the tap, or PFAS-specific ion exchange | NSF/ANSI 53 or 58 for PFAS removal | PFAS below |
| Protozoa such as Giardia or Cryptosporidium | A filter certified for cyst reduction | NSF/ANSI 53 (cyst reduction). These don’t remove viruses or bacteria. | |
| Bacteria and viruses, on a well or water of unknown quality | Ultraviolet (UV) system | NSF/ANSI 55 Class A for contaminated water. Class B is only for water that is already acceptable. | On a well below |
| Sand, sediment, rust or particles | Sediment filter | Ask which standard | On a well below |
| Iron, manganese or a sulphur smell, on a well | Greensand filter | Ask which standard | On a well below |
| Nitrate, on a well | Reverse osmosis or distillation | NSF/ANSI 58 (reverse osmosis) or 62 (distillers); check that nitrate is among the certified claims | Well water testing |
| Hardness | Water softener | NSF/ANSI 44 | Water softeners |
Sources: Health Canada, Questions and Answers on Drinking Water Treatment Devices[1] and Water talk: PFAS in drinking water[2]; Government of Ontario, Testing and treating private water wells.[3]
What the certification mark means
Health Canada lists six standards for home water treatment devices:[1]
- NSF/ANSI 42: aesthetic effects, such as taste and odour
- NSF/ANSI 44: water softeners
- NSF/ANSI 53: health effects, such as lead, PFAS or cysts
- NSF/ANSI 55: ultraviolet systems
- NSF/ANSI 58: reverse osmosis systems
- NSF/ANSI 62: distillers
When a device is certified to one of these, Health Canada says it means the device doesn’t add anything harmful to the water, and the maker’s claims covered by that standard have been verified.[1] Makers can also make claims outside the standard, so read the packaging to see which claims were actually certified.
Look for a certification mark and a statement that the device meets one of the standards.[1] Certification bodies are accredited by the Standards Council of Canada. Health Canada lists CSA Group, NSF International, the Water Quality Association, UL LLC, the Bureau de normalisation du Québec, Truesdail Laboratories and the International Association of Plumbing and Mechanical Officials; each keeps an online list of certified devices. Health Canada also says a mark accredited in Canada should have a letter C in its lower left corner.[4]
There is no federal requirement in Canada for point-of-use filters to be tested or certified, Health Canada says, and there is no health-based standard yet for ozonators or “microbial purifiers”.[4][1] False or misleading claims about devices are prohibited under federal law.
Where the filter goes
- At one tap (point of use). Filters on the faucet, in a pitcher or bottle, or in a fridge’s water dispenser and ice maker, plus under sink filters and reverse osmosis.[4]
- Where water enters your home (point of entry). Ontario calls these in-line systems: they treat water for the whole home.[3] See whole house filters.
Health Canada says a reverse osmosis system should only be installed at the tap.[2] Installed further up the line, the treated water may corrode plumbing and draw other contaminants, like lead, into the water.
Filters for PFAS {#pfas}
PFAS are a large family of synthetic chemicals that last a long time in the environment.[2] Health Canada has set an objective of 30 nanograms per litre for the total of 25 specific PFAS in drinking water. It says the data it has suggest PFAS are present across Canada at levels generally below that objective, and can be higher near facilities that use a lot of them, places where firefighting foam was used, landfills and wastewater plants.
If you’re concerned, Health Canada says to contact your municipality, local drinking water authority or public health unit first.[2] If you do have PFAS in your water, its options are:
- an activated carbon filter at the tap or where water enters the home, certified to NSF/ANSI 53 for PFAS removal
- a reverse osmosis system at the tap, certified to NSF/ANSI 58 for PFAS removal
- an ion exchange system with a resin made for PFAS. None is certified yet for home use; check the maker’s information carefully, and Health Canada strongly recommends the system meet NSF/ANSI 61 for drinking water materials.
Boiling won’t remove PFAS.[2] Bathing, showering, brushing teeth, washing dishes and doing laundry are unlikely to significantly raise your risk. If you’re pregnant, breastfeeding or making infant formula and concerned, Health Canada says you may wish to use another water source, such as bottled water, or a unit certified for PFAS removal. Ask your local authority how to dispose of used filters and media, so the PFAS don’t go back into the environment.
In Hamilton, the City has looked into PFOS in wells near John C. Munro Airport; see well water testing.[5]
On a well {#on-a-well}
Test first, then treat what the test finds. Health Canada says people on a well should have their water tested regularly, and their public health unit can advise which contaminants to test for.[1] See well water testing.
Ontario’s guide for well owners says no single treatment works for everything, and that its treatment table is guidance, not recommendations.[3] From that table:
- UV kills bacteria and viruses, but needs filtering first to catch microbes in dirt particles, a slow flow and a clean lamp.
- Greensand removes moderate amounts of iron and manganese, and Health Canada says it removes sulphur smell.[1] It needs regular backwashing and is not easy to operate or maintain.
- Activated carbon removes tastes, odours and trace organic chemicals, but not minerals or larger amounts of chemicals.
- Reverse osmosis removes nitrate, sulphate, hardness, most microbes and particles, but hard water can plug its membrane.
A strong sulphur smell is not a health hazard, Health Canada says; it is a nuisance.[1] Before you buy, Ontario suggests understanding what the system will do and its full cost: purchase and installation, replacement filters or bulbs, electricity and maintenance.[3] If your water doesn’t meet the Canadian guidelines, Health Canada says to consult a qualified water treatment specialist. See water softeners for hardness.
Water treatment devices and filters can’t be offered or sold at your home unless you asked the business to come, with some exceptions; see “free water test” offers.[6]
Keeping a filter working
Follow the maker’s instructions for maintenance and replacement. Health Canada says maintenance, “although sometimes burdensome, is very important to ensure their continued efficacy”.[1] Ontario adds that an activated carbon filter must be replaced regularly, it’s hard to tell when it’s used up, and an old one can become a source of bacteria and taste and odour problems.[3]
Is filtered water better than tap water?
Health Canada’s answer is that water meeting the Canadian guidelines does not usually need more treatment for health reasons.[1] Whether to filter depends on your situation: what you want to change, or what a test has found. For your city’s results, see is tap water safe to drink in Ontario.
Do water filters remove fluoride? For very high natural fluoride in a well, Ontario’s well guide says to distill drinking water or use bottled water.[3]
Sources
- Health Canada, Questions and Answers on Drinking Water Treatment Devices. Checked . ↩︎
- Health Canada, Water talk: PFAS in drinking water. Checked . ↩︎
- Government of Ontario, Testing and treating private water wells. Checked . ↩︎
- Health Canada, Infographic: Finding a drinking water filter. Checked . ↩︎
- City of Hamilton, PFOS and Propylene Glycol. Checked . ↩︎
- Government of Ontario, Door-to-door sales and home service contracts. Checked . ↩︎