Residential and Commercial Water Softeners Technical Overview

Water softeners as we know them have been around since the 1940's.

The basic process is to flow water containing the ions of calcium and magnesium (the salts of which are called hardness) across beads of plastic called ion exchange resin or resin of synthetic zeolite where the calcium and magnesium are exchanged for sodium from salt (sodium chloride) or potassium from potassium chloride.

The calcium, magnesium, sodium and potassium all exist in the water as ion which by definition are dissolved and cannot be seen. The hardness ions cause scale in pipes, soap curd, water heater failure, poor soap use, etc. Sodium and potassium do not cause these problems so there are aesthetic and financial benefits to softening water.

The photo shows some standard beads of resin. They are about 1/64" in diameter and the color varies from almost white to black depending on the manufacturer. Made of a blend of 92% styrene and 8% divinyl benzene it is durable from just above freezing to boiling temperatures. The benzene compound is mildly soluble in water with free chlorine, so pre-treatment with activated carbon extends the life measurably. Pan on a resin life of 15 years + with proper care. The resin used is the same for commercial water softeners as well as residential.

Running water across the resin is called the service cycle. When all of the sodium is gone, the water softener is said to be exhausted. At that point sodium or potassium mixed with water called brine must be introduced in a process called regeneration where the calcium and magnesium is run to drain and is replaced with the sodium or potassium. The photo shows basic internals. The resin capacity is considered used up when exhaustion is reached. Water hardness is expressed as grains or grains per gallon (GPG) or as mg/l and 1 GPG+17.1 mg/l. The capacity of resin is expressed as kilo (thousands) of grains per cubic foot. The normal capacity of resin is 30 kilo grains/30,000 grains per cubic foot. As an example: Water containing 10 grains of hardness and a 1 cubic foot commercial or residential softener. 30,000/10=3,000 gallons. This is the frequency or regeneration. Commercial water softeners should always be sized by a professional!
Some key numbers used to size and operate a residential or commercial water softener:

To get 30,000 grains from a cu. ft. of resin, salt with 15 pounds of salt.
To get 20,000 grains from a cu. ft. of resin, salt with 8 pounds of salt.
One gallon of water added to salt will dissolve 3 pounds of salt and produce brine for regeneration.
Intermittent max. flow ranges from 5 to 15 GPM/cu. ft of resin.
People within a home in the US consume 60-75 gallons per day per person.

For more information on water treatment for your home or business, click on one of the following topics:

Reverse Osmosis Overview, Residential Reverse Osmosis, Commercial Reverse Osmosis, Water Softener Overview, Commercial Water Softeners, Residential Water Softeners, Water Filter Overview, Backwashing Water Filters, Non-Chemical Water Conditioners, Aquafer Water Conditioner, Maxi-Cure Water Filter, Scale Prevention Devices, Ultra Violet Disinfection, High Purity Water, De-ionization, Specialty Water Filtration, Reverse Osmosis Repair, Commercial Water Softener Repair, Residential Water Troubleshooting, Commercial Water Troubleshooting.

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