7 Evidence-Backed Benefits of a Water Softener in Hard-Water Canadian Cities (And the Claims That Don't Hold Up)

Every one of the claims below shows up in softener marketing, and each one reaches further than the evidence does. Setting them aside does not weaken the case for a softener in very hard water. It simply keeps the decision resting on the benefits that were measured.

A softener will clear up eczema

This is the most thoroughly tested claim of all, and the answer was no. In a British trial funded by the National Institute for Health Research, 336 children with moderate or severe eczema, all living with water at or above 200 mg/L, were randomly assigned to get a softener or to continue with usual care. After 12 weeks, nurses who did not know which homes had softeners scored the children's skin, and the two groups had improved by 20 and 22 per cent, a difference that was not statistically meaningful. The authors concluded that softeners gave no added benefit.

Parents in the softener group did report small improvements, which the researchers put down to the fact that families knew a softener had been installed. A later review of sixteen studies reached the same conclusion about treatment, while noting that children who grow up with harder water do have slightly higher odds of eczema, on evidence it rated as very low certainty. Whether softening from birth could prevent eczema is still an open question, since the only trial so far was a small pilot that was never designed to answer it. For now, the fair grade is unsupported for treatment and weak for prevention, and a skin concern belongs with your doctor.

It lowers the energy use of an electric water heater

The same study that supports the efficiency benefit for gas heaters found nothing of the kind for electric tanks. Electric heaters on hard water ran at 99.5 per cent efficiency at the start of the test and 99.5 per cent at the end, because the elements sit fully submerged and keep transferring heat even when coated. The report expects a scaled element to wear out sooner, which is a sensible expectation, but it was not measured. If your tank is electric, the efficiency argument does not apply to you.

Appliances will last years longer

It sounds like common sense, and it may even be true, but no study has measured it. Battelle ran its dishwashers and washing machines for 240 cycles over 30 days, then opened them up. The machines on very hard water had visible scale on their interior surfaces and the softened ones did not, and every machine in both groups completed the test. Visible scale after a month is evidence of scale. It is not evidence of a lifespan, so any promise of doubled appliance life earns a weak grade.

Softened water is healthier or purer

A softener swaps calcium and magnesium for sodium, and that is all it does. It does not remove bacteria, lead, or other contaminants, and Health Canada is clear that there is no health-based limit for hardness in the first place, stating that there is insufficient evidence to support a health-based value for it. Hard water is safe to drink, and softened water is not an upgrade in purity.

If cleaner drinking water is what you are after, a softener is the wrong tool, and our guide to what reverse osmosis removes and what it doesn't is a better place to start.

Every Canadian home needs one

This one is contradicted by the utilities themselves. The City of Toronto tells residents that its Lake Ontario supply contains relatively low levels of hardness minerals and that water softening systems are usually not needed, suggesting vinegar for any deposits on fixtures. Some dealer pages describe Ontario water as averaging 250 parts per million, which is roughly double what Toronto, Peel, Durham, Hamilton, and London show in their most recent published figures.

As for the promise that a softener pays for itself, the only figures behind it are modelled estimates in the industry-funded study, built on very hard water. We have left dollar amounts out of this article for that reason, since your own result would depend on your hardness, your water heater, and your household.

Potassium chloride is the usual alternative for households that want to avoid sodium, and we compare it with the other options in our guide to water softener salt types.

Salt down the drain

Every regeneration sends salty water to the sewer, and treatment plants do not take the chloride back out. Waterloo Region, where softeners are close to universal, has put numbers on it, estimating that about 142,000 homes with softeners create 1.5 billion litres of backwash a year, which accounts for about 7 per cent of a household's water use. The Region also reports chloride rising in its municipal wells toward Ontario's 250 mg/L objective.

We did not find a Canadian municipality that bans softener discharge. What the Region does instead is encourage restraint, by asking residents to set the softener to the correct hardness for their zone, to choose an efficient model, and to consider softening the hot water only. It currently offers a one-time $50 rebate, for a limited time, to homeowners who replumb a salt-based softener that way. A hot-water-only setup keeps the water heater, dishwasher, and shower benefits while leaving your cold taps and your garden hose unsoftened.

Septic systems

If you are on a septic system, there is Canadian evidence to reassure you. A University of Guelph study funded by Canada Mortgage and Housing Corporation compared 39 household septic tanks, 17 of them receiving softener backwash, and found no significant effect on how the tanks functioned. Chloride and sodium in the sludge were much higher in the tanks receiving backwash, though, and the authors cautioned that elevated chloride may speed up corrosion in reinforced concrete tanks. The study looked at the tank and not the leaching bed, so mention your softener to whoever pumps and inspects your system.

A faster-wearing anode rod

Here is the trade-off almost nobody mentions. The thin layer of scale that hard water leaves inside a steel tank offers a little protection, and without it the sacrificial anode rod does more of the work. Water heater manufacturers say so directly, with one Canadian manual warning owners that the anode rod will deplete faster than normal with a water softener. A softener protects your tank from scale and asks you to check the anode more often in return, which is a fair exchange as long as you know about it.

Put the two tables side by side and the answer becomes much less of a guess. The benefits are real, they were measured in very hard water, and they fade as hardness falls.

• Below 60 mg/L, as in Vancouver, Victoria, Halifax, Ottawa's central supply, and Thunder Bay: there is very little hardness to remove, and none of the measured benefits applies in any meaningful way.
• Around 110 to 130 mg/L, as in Toronto, Peel, Durham's lakeshore, Hamilton, London, Kingston, Montréal, and Kelowna: you are at about 7 grains, less than half the lowest hardness the detergent studies tested. Scale builds slowly here. A softener is a comfort choice in this band, and descaling a kettle or a tankless heater every few years is a reasonable alternative.
• Around 150 to 200 mg/L, as in Lethbridge, Saskatoon, Edmonton, and north Calgary: the benefits begin to show, especially if you have a tankless or gas water heater. Softening the hot water only is well worth considering.
• Above 200 mg/L, as in Regina, Red Deer, south Calgary, Barrie's well-supplied areas, Kitchener, Waterloo, and Guelph: this is the water the studies were about. Health Canada describes supplies above 200 mg/L as poor and those above 500 mg/L as possibly requiring softening, and the scale, fixture, dishwashing, and laundry benefits should all be noticeable.

If you are still not sure which band your home falls into, the clues around your kettle and taps can help, and we cover them in Signs Your Home Has Hard Water (And What to Do About It).

You now have what a salesperson rarely offers, which is the measured benefits, the claims that fell short, and the number for your own tap. Look up your zone, decide which of the seven benefits you would notice, and keep the kitchen tap unsoftened if you go ahead. Whatever you choose, you will be choosing with the evidence in hand.