Soft Water’s Not That Hard!

By Jennifer Casey
Published: May 1, 2015 | Last updated: April 9, 2021 09:50:11
Key Takeaways

Softened water is one of those “hate it or love it” things; however, regardless of which camp you’re in, knowing a little bit about water softener can help you better evaluate your water needs.

Source: Anette Linnea Rasmussen/

Softened water is a divisive issue. Like cilantro, two-stroke engines and Bon Iver, most people either love it or hate it. Proponents love the clean bathroom fixtures, superior lather of soap and laundry detergent and streak-free windows.


Haters primarily dislike “that slimy feeling” softened water leaves on the skin and the added salt, which requires a point-of-use filter for drinking water and plants. Regardless of which camp you’re in, knowing a little bit about water softeners can help you make an informed decision when evaluating your water needs.

Softeners look a little like an oxygen tank are available in several sizes and can use either sodium chloride (salt) or potassium chloride as a medium. They work by exchanging the hardness (that is, minerals) in water for either sodium or potassium using cationic exchange.


Hardness is measured in “grains;” the more grains of hardness present in the water, the higher the salt or potassium content of the softened water. Gardeners who use a reverse osmosis (RO) filter to prevent nutrient lockout of their plants might want to add a softener before their system to reduce hardness and help extend the life of their RO system.

Soft water is so named because it isn’t hard. In researching this article, I came across the Water Quality Association's reason for the designation of “hard” and “soft,” which is this: years ago, when people did their laundry by hand, they found that heavily mineralized water made it hard to wash clothes—hence, hard water.

Apparently, their solution was to collect rainwater to wash with, which was referred to as soft. This might seem like a lot of trouble to go to for the sake of washing a few dirty clothes, but check this out: the WQA also cites a Purdue University study that found clothes washed in hard water wore out 15 times faster than those washed in softened water. This statistic is attributed to the way that suspended minerals simply rub on clothing fibers and wear them out, which seems somewhat obvious.


Apparently detergent is another factor. Laundry soap was originally highly alkaline, which helped to create a water environment in which dirt was easily released. As people got tired of saving rainwater for their laundry, their laundry soap wasn’t working very well to wash their clothes.

Soap-based cleaners combine with hard water to create what is somewhat disgustingly called soap curd. This unappealing substance is a combination of soap and hard-water minerals, and is what ends up coating your shower door, bathroom fixtures, etc. It’s also hard on fabrics. Enter detergent.


Detergent was developed as a petroleum product and dissolves nicely in hard water. This is helpful when doing laundry, but not so helpful for the planet. Many people are doing their best to avoid petroleum products whenever possible, and synthetic detergents are not nearly as biodegradable as their soapy predecessors.

If you cringe at the price of clothes these days, remember that wearing out those skinny jeans 15 times faster can really add up. As innocuous as doing laundry might seem, the effects of hard water can impede the process of cleaning your clothing, towels, and linens which costs money.

Although synthetic detergent mitigates some of the soap curd (gross) associated with laundering in hard water, the best solution is to simply use a water softener. Once used, a return to traditional laundry soap will help keep your clothes clean and the planet happy, or synthetic detergents can be used in much smaller amounts than before, saving more money.

Hot water use will decrease, as the soap will do an excellent job in cool water, saving on energy costs. Additionally, using a water softener ensures that your skin will no longer be repository for soap curd residue.

Slippery = clean?

That’s right; soap curd is responsible for that squeaky clean feeling on skin and hair… maybe. The lack of squeak, the feeling that maybe the soap hasn’t rinsed entirely off, is one of the most controversial effects of softeners.

According to some, the slippery feeling skin gets in softened water is a result of the ionic exchange that occurs when mineral content is exchanged for sodium or potassium (depending on which media is used in the softener) and the resultant ions keep the soap from sticking to the water and getting rinsed off.

Sounds pretty legit, but check out the website for any water softening company and the explanation changes. These companies claim that the slippery feeling is actually the way that clean skin feels without the rubbery squeak of soap curd.

Both sides acknowledge that since soap works much better in soft water, people sometimes use the levels they used in hard water—much more than is necessary in soft water. It’s a tough claim to parse, as rinsing a soapy sink in softened water leaves no hint of curdy ring, which points to superior rinsing ability and the claim of the makers of softeners.

Then again, rinsing in naturally soft water like rainwater or water softened by other means like RO, both of which wouldn’t contain which added sodium or potassium, doesn’t seem to cause any sort of slimy skin-feel, regardless of soap.

I failed to find any third-party study which actually measured soap residue left after a softened water rinse vs. a hard water rinse. Anecdotally, some users of softeners rave about the improved condition of skin and hair without soap or mineral residue when using a softener, while others bemoan the drying effects of softened water on their person.

When it comes to the skin/hair debate, it may just be a matter of preference. Personally, I hypothesize that it might very well be the way that the sodium/potassium ions feel on the skin, not necessarily that soap is being left behind.

How does soft water taste?

The WQA, along with softener companies, claim that unless one is on a severely salt-restricted diet, the added salt in softened water isn’t a health risk, with an average of about 0.02 oz. of added sodium per gallon of water.

While this amount is about one-fifth of the sodium in skim milk, I’d be more concerned with taste. In my humble opinion, the drinking water that tastes the best is water that has been filtered using RO to take 96 to 99% of all contaminants out, and then treated with a remineralizing post filter to add back about 30 to 50 ppm of calcium carbonate for that clean, crisp taste.

Drinking water that has been demineralized (whether by an ion exchange softener or RO) is another source of controversy, some claiming that it strips the body of its own minerals, and other pointing to the fact that many dissolved minerals on water are too large to be absorbed by the body.

Using a remineralizing post filter is an easy solution, adding minerals your body can use and allowing RO to remove many other harmful contaminants. An added benefit of using a softener is that it acts as excellent pre-filtration for a RO drinking water or plant water system, preserving expensive RO membranes and saving you money!

Should I give my plants soft water or hard water?

Let’s be clear—sodium-chloride softened water should never be given to your plants, especially in a hydroponic garden, as plants are very sensitive to levels of sodium. Some outdoor gardeners who have a whole-house softener might choose to use potassium chloride media, as the relatively low levels found in softened water are not generally harmful for lawns and other non-sensitive plants. However, hydroponic gardens can also be disrupted by excessive potassium.

A softener can, however, benefit your plants in much the same way it can benefit your drinking water—as a pre-filter for RO. Reverse osmosis has become the gold-standard of water treatment in hydroponics, removing blocky, unusable minerals, heavy metals, volatile organic compounds and a host of other toxic contaminants and preventing nutrient lockout.

The most expensive parts of a RO filter are the membranes—and those with large gardens using lots of water know that replacing those membranes can add up. Incidentally, the very hardness that prompts many gardeners to purchase an RO system is the same hardness that can prematurely clog the RO membranes.

Since softeners exchange that damaging hardness for sodium or potassium chloride, the membrane’s job is much easier. Both sodium chloride and potassium chloride are easily removed by RO membranes, which will remove 99% of sodium or potassium chloride.

The bottom line is that if you have hard water, you should probably get a softener. Whether or not you use the softened water for your whole house, for your shower or just to preserve your RO membranes in the greenhouse is a matter of preference.

The money it can save you in the laundry room and the garden is undeniable. Don’t worry, you can still hate cilantro, but now you can spend less money growing it by using a softener to assist your RO system!


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Written by Jennifer Casey

Profile Picture of Jennifer Casey
Jennifer Casey loves her two dogs, her husband, the amazing garden he grows, and living in the country. In that order. Crafting, reading, and cooking food she picks from the garden are her favorite ways to spend her time.

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