Quick Answer: Diamond Crystal Potassium Chloride Pellets are the bag to buy online right now. They work in any standard softener, and Diamond Crystal's potassium pellets are reported at 99.1% pure. Morton's potassium pellets and Compass Minerals Nature's Own are solid in-store backups. Whichever bag you buy, plan to raise your softener's salt dose (or hardness setting) by roughly 20% when you switch, or you'll get hard water back before regeneration.
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You're probably here because a doctor said "watch your sodium," or someone in the house is on a low-sodium diet, or you'd rather not pipe salty regeneration water into a septic field or onto the yard. Potassium chloride solves the sodium problem. It also costs more per bag, softens less per pound and needs a settings change that most people skip.
This page is short on picks on purpose. Only a handful of companies make potassium chloride for softeners, and only one of them currently has a real, in-stock, single-bag listing we could verify on Amazon. We're not padding the list with food-grade powder or mystery resellers just to reach five.
In this guide
First, is sodium from your softener actually a big deal?
It depends on your hardness. A softener swaps each hardness ion for sodium, so the harder your raw water, the more sodium ends up in the softened water. A widely cited estimate is about 7.5 to 8 mg of sodium per liter for every grain per gallon of hardness removed.
Work it out for a fairly typical well:
- Raw hardness: 15 gpg
- Sodium added: about 15 × 7.8 ≈ 117 mg per liter
- If you drink 2 liters of softened tap water a day: roughly 230 mg of sodium
That's about what you'd get from a slice or two of bread. It's small next to a typical diet, but it isn't nothing if your doctor has set a tight daily cap. At 5 gpg it barely registers. At 30 gpg it adds up. Our breakdown of sodium in softened water has the full table.
Here's the honest alternative: if you only care about drinking water, an under-sink reverse osmosis filter at the kitchen tap removes most of the sodium. Then you can keep buying cheaper sodium chloride for the rest of the house. Plenty of households do exactly that. Potassium makes the most sense when you want sodium out of all the water (cooking, coffee, the fridge line) or when local rules or your septic system push you away from sodium brine.
What switching will really cost you
Potassium chloride is less efficient at regenerating resin than sodium chloride. A common recommendation, which shows up in published brand comparisons, is to bump the hardness setting up by about 20% when you switch. On many valves, you can instead raise the salt dose per regeneration.
What that means in bags:
| Sodium chloride | Potassium chloride | |
|---|---|---|
| Monthly salt use (example) | 1 × 40 lb bag | ~1.2 bags |
| Bags per year | 12 | ~14–15 |
| Price per bag | Lower | Noticeably higher |
The extra bags are the smaller cost. The bigger one is the price per bag, which runs well above sodium chloride. Before you commit, check the current price on the listing below and multiply by fifteen.
The potassium bags worth buying
Diamond Crystal Potassium Chloride Pellets
This is Diamond Crystal's 40 lb bag of potassium chloride pellets, made by Cargill (item 7376). Diamond Crystal's long-running potassium line has been sold as K-Life, and the company now also markets its potassium pellets as "Potassium Chloride Salt Alternative." One published brand comparison lists Diamond Crystal's potassium pellets at 99.1% pure potassium chloride, which is the most specific purity number we could find for any potassium product.
Why it's our pick: right now it's the one softener-grade potassium chloride bag we could confirm in stock as a real, single-bag listing on Amazon. It works in any standard softener that takes pellets. Pick it too if you're already using Diamond Crystal salt and want to stay in the same family.
What to watch for: like any compressed pellet, it can bridge if the tank sits half empty in a humid garage. Poke the salt with a broom handle every month or two to check for a crust. And potassium stock comes and goes more than sodium salt does, so don't wait until the tank is empty to reorder.
If you'd rather buy locally: Morton and Compass Minerals
Two other potassium pellets are worth knowing about, even though neither is currently in stock on Amazon. Morton Potassium Chloride Pellets are the ones you're most likely to see at a hardware or big-box store. Morton describes them as 99% sodium free and sells them in a 40 lb bag. Compass Minerals Nature's Own (part 38240) is a less well-known 40 lb potassium pellet. We couldn't find a published purity figure for it, so we won't make one up.
Either one is a fine fallback for when the Diamond Crystal bag is out of stock, which happens with potassium salt more than with sodium salt. Treat them as standard softener-grade potassium pellets and run them at the same higher dose.
Switching over without a week of hard water
- Let the sodium salt run low. You don't need to empty the tank completely. Mixing during the changeover is generally fine, and there's more on that in our piece on whether you can mix softener salts.
- Change the setting. On a metered valve like a Fleck 5600SXT or Clack WS1, raise the hardness entry about 20%. For example, 15 gpg becomes 18. You can also increase the salt dose instead. Our guide to setting the salt dose shows where both settings live on common valves.
- Fill with potassium and do a manual regeneration so the resin starts out loaded with potassium.
- Test the soft water a week later. If hardness shows up before the scheduled regeneration, raise the setting again.
The drain-water argument (and its limits)
Some people switch for reasons that have nothing to do with diet. During regeneration, a softener sends a slug of brine down the drain. With sodium chloride, that brine is sodium-heavy. With potassium chloride, it carries potassium instead, and potassium is a plant nutrient. That's why potassium comes up with homeowners who drain to a dry well or a septic field, or who live somewhere with brine-discharge rules.
Don't oversell it to yourself, though. The discharge is still salty, because the chloride half doesn't go anywhere, so potassium doesn't make it fine to dump softener brine onto your lawn. If reusing that water is the goal, read whether you can reuse softener discharge before you plumb anything outside.
Who should stay with regular salt
- If your hardness is under about 7 gpg, the extra sodium is already very low. Paying more for potassium is hard to justify unless a doctor specifically asked for it.
- If you only want sodium-free drinking water, an RO faucet is usually cheaper over time than switching the whole house.
- If you have kidney disease or take potassium-sparing medication, ask your doctor first. Potassium in your water isn't automatically a better choice for you, and our page on softeners for low-sodium diets covers this in more detail.