What softener salt does

A water softener passes hard water through a bed of ion-exchange resin, which captures calcium and magnesium and releases sodium. When the resin is exhausted, the softener draws concentrated brine from its salt tank and flushes it through the resin, driving off the captured hardness and reloading it with sodium. The salt is the regenerant: it dissolves in the brine tank, does its work in the resin bed, and goes to drain. Anything in the salt that does not dissolve stays in the tank.

The forms of softener salt

Buy by residue, not by price

This is the most important section of this page.

Insolubles — clay, sand, gypsum and other material that does not dissolve — accumulate at the bottom of the brine tank with every bag. The arithmetic is simple: the insolubles percentage tells you how many kilograms of residue each tonne of salt leaves behind.

Insolubles: tablet values from published EN 973 Type A product specifications; raw salt ranges from Salt Partners (2021). Residue is arithmetic: insolubles percentage multiplied by 1,000 kg.

Bridging and mushing

Standards

Europe: EN 973

In Europe, salt used to regenerate ion-exchangers treating water for human consumption is covered by EN 973, Chemicals used for treatment of water intended for human consumption — Sodium chloride for regeneration of ion exchangers. The standard defines Types A, B and C. Type A is the grade most premium softener tablets declare. Published Type A tablet specifications show NaCl of at least 99.4% (typically 99.9%) and insolubles of at most 0.05% (typically 0.01%). One commercial tablet data sheet also lists calcium plus magnesium at no more than 50 ppm, sulphate at no more than 400 ppm, iron below 1 ppm, and limits for lead (1 ppm), arsenic (0.3 ppm), cadmium (0.5 ppm) and mercury (below 0.1 ppm). Ask your supplier which type their salt meets, and for the test report, not just the claim on the bag.

United States: AWWA B200

In the United States, the American Water Works Association standard AWWA B200 covers sodium chloride for water treatment. Requirements differ from EN 973, so a product certified to one is not automatically compliant with the other.

Elsewhere

Many Gulf, African and Asian markets have no dedicated softener-salt standard and rely on importer specifications or EN 973 by reference. If your market has none, we recommend writing EN 973 Type A, or its key numbers, into your contract.

Dishwasher salt and other small-pack uses

Dishwashers with built-in softeners need coarse, high-purity granular salt, sold in consumer packs, typically of one or two kilograms. Fine table salt is unsuitable: it can block the softener compartment, and anti-caking agents and additives are unwanted. The same purity logic applies to salt for small point-of-use softeners, coffee machines and laboratory water systems. These are natural private-label products for retailers, and they are among the few salt products where a 1 kg pack is the main format rather than an exception.

Specification: what should be in the contract

Where Indian softener salt fits — honestly

Salt is heavy and cheap, so freight matters as much as purity. Indian softener salt is most competitive in markets a short or moderate voyage from Gujarat: the Gulf states, where commercial softening for hotels, laundries, cooling and boilers is widespread; East and West Africa; and South and South-East Asia. In Europe, long-established local producers sell tablets close to their customers, and Indian tablets compete mainly in private label for importers who value price and flexibility of packaging. We would rather tell a European buyer that than pretend Indian tablets are always cheaper delivered. Trade statistics for salt (HS 2501) do not separate softener salt from other salt, so we do not quote a market share for this grade.

Packing: private labelling from 1 kg to 50 kg, and bulk shipments

RNG Agro Exports offers private labelling from 1 kg to 50 kg pack sizes, and we also handle bulk shipments. Softener salt is mostly sold under the retailer’s or distributor’s brand, so packaging is often the product.

Working with RNG Agro Exports

We are based in Rajkot, Gujarat, in the state that produces about 85% of India’s salt, and we supply tablets, granules and washed crystal salt from qualified producers there. For softener-salt buyers we start with the insolubles figure, convert it into residue per tonne, and quote against the standard your market expects. We send a test report with the first shipment, and we print to your brand in your languages. If your customers would be better served by tablets than the crystal salt you asked for, we will say so.

Frequently asked questions

What is the best salt for a water softener?

For most softeners, high-purity tablets or pellets, because they leave the least residue and resist mushing. Insolubles, the material that does not dissolve, accumulate in the brine tank with every bag, and the insolubles percentage tells you how much residue each tonne leaves. Published EN 973 Type A tablet specifications show insolubles of at most 0.05%, typically 0.01%, which is at most about half a kilogram per tonne. Raw sea salt typically carries 0.1–1% insolubles, or 1–10 kg per tonne, and raw rock salt 1–10%, or 10–100 kg per tonne, according to Salt Partners. Washed crystal salt can be acceptable for commercial softeners whose tanks are cleaned regularly, but rock salt is the least suitable.

What is EN 973 Type A?

EN 973 is the European standard for sodium chloride used to regenerate ion-exchangers treating water intended for human consumption, and it defines Types A, B and C. Type A is the grade most premium softener tablets declare. Published Type A tablet specifications show sodium chloride of at least 99.4%, typically 99.9%, and insolubles of at most 0.05%, typically 0.01%. One commercial data sheet also lists calcium plus magnesium at no more than 50 ppm, sulphate at no more than 400 ppm, iron below 1 ppm, and limits for lead, arsenic, cadmium and mercury. In the United States the corresponding standard is AWWA B200, whose requirements differ. Ask any supplier which standard and type their salt meets, and for the test report rather than the claim on the bag.

What causes bridging and mushing in a brine tank?

Bridging is a hard crust that forms across the brine tank above the water, so the salt above it never reaches the water; the brine becomes weak and the softener regenerates poorly while the tank looks full. Humidity, temperature swings, overfilling and damp or caked salt make it more likely, and tablets of consistent shape and purity bridge less. Mushing is fine salt recrystallising into dense sludge at the bottom of the tank, blocking the brine intake; poorly graded crystal salt with many fines mushes more, while compressed tablets resist it. Separately, insolubles build up as sludge in direct proportion to their percentage in the salt, which is why purity and grading both matter.

Can I use table salt in a dishwasher?

No. Dishwashers with built-in softeners need coarse, high-purity granular dishwasher salt. Fine table salt can block the softener compartment, and the anti-caking agents and other additives in table salt are unwanted there. Dishwasher salt is sold in consumer packs, typically of one or two kilograms, and is a natural private-label product for supermarkets and household-goods retailers. The same purity logic applies to salt for small point-of-use softeners, coffee machines and laboratory water systems. If you sell dishwasher salt under your own brand, specify high purity, low insolubles, a coarse grading with few fines, no additives, and packaging with a good moisture barrier.

Do you offer private labelling and bulk shipments for softener salt?

Yes. RNG Agro Exports offers private labelling from 1 kg to 50 kg pack sizes and also handles bulk shipments. Typical formats are 1 kg to 2 kg packs of dishwasher salt for retailers, 5 kg bags for small household units, 10 kg and 25 kg bags of tablets for household and commercial softeners, 50 kg bags for commercial plants, big bags of about one tonne for industrial softening and boiler-water plants, and crystal salt in bulk containers for large users and repackers, quoted on enquiry. We print to your brand in the languages of your market and supply a test report against the standard you declare. Tell us the product, the standard, the destination and the annual quantity.

• For most softeners, high-purity tablets or pellets, because they leave the least residue and resist mushing. Insolubles, the material that does not dissolve, accumulate in the brine tank with every bag, and the insolubles percentage tells you how much residue each tonne leaves. Published EN 973 Type A tablet specifications show insolubles of at most 0.05%, typically 0.01%, which is at most about half a kilogram per tonne. Raw sea salt typically carries 0.1–1% insolubles, or 1–10 kg per tonne, and raw rock salt 1–10%, or 10–100 kg per tonne, according to Salt Partners. Washed crystal salt can be acceptable for commercial softeners whose tanks are cleaned regularly, but rock salt is the least suitable.
• EN 973 is the European standard for sodium chloride used to regenerate ion-exchangers treating water intended for human consumption, and it defines Types A, B and C. Type A is the grade most premium softener tablets declare. Published Type A tablet specifications show sodium chloride of at least 99.4%, typically 99.9%, and insolubles of at most 0.05%, typically 0.01%. One commercial data sheet also lists calcium plus magnesium at no more than 50 ppm, sulphate at no more than 400 ppm, iron below 1 ppm, and limits for lead, arsenic, cadmium and mercury. In the United States the corresponding standard is AWWA B200, whose requirements differ. Ask any supplier which standard and type their salt meets, and for the test report rather than the claim on the bag.
• Bridging is a hard crust that forms across the brine tank above the water, so the salt above it never reaches the water; the brine becomes weak and the softener regenerates poorly while the tank looks full. Humidity, temperature swings, overfilling and damp or caked salt make it more likely, and tablets of consistent shape and purity bridge less. Mushing is fine salt recrystallising into dense sludge at the bottom of the tank, blocking the brine intake; poorly graded crystal salt with many fines mushes more, while compressed tablets resist it. Separately, insolubles build up as sludge in direct proportion to their percentage in the salt, which is why purity and grading both matter.
• No. Dishwashers with built-in softeners need coarse, high-purity granular dishwasher salt. Fine table salt can block the softener compartment, and the anti-caking agents and other additives in table salt are unwanted there. Dishwasher salt is sold in consumer packs, typically of one or two kilograms, and is a natural private-label product for supermarkets and household-goods retailers. The same purity logic applies to salt for small point-of-use softeners, coffee machines and laboratory water systems. If you sell dishwasher salt under your own brand, specify high purity, low insolubles, a coarse grading with few fines, no additives, and packaging with a good moisture barrier.

What this means for a distributor or brand owner. A tonne of the cheapest rock salt can leave up to a hundred times more sludge in your customers’ brine tanks than a tonne of good tablets. That sludge is a service call, a cleaned tank, a softener that regenerated poorly, or a customer who blames your brand. Price per tonne is the number on your purchase order. Residue per tonne is the number your customer lives with. When you compare offers, convert each insolubles figure into kilograms per tonne and price it in. Cheap salt is often expensive salt that has not sent its bill yet.