How do water softeners work?
Have you ever wondered what a water softener is and how it works.
It’s easy to forget how important water is in our lives. Of course we need it in our diet, but in our homes, it’s a tool–a fluid medium that carries material from one place to the next. And one of the reasons it does this job well is that it’s very good at holding things, either by suspending them or dissolving them.
Unlike most tools, though, water doesn’t come with an instruction manual. If it did, you’d know why the dishes you thought were washed are covered with spots when dry, why the water in your shower leaves a film on everything it touches, and why what you thought was clean water has clogged up your plumbing system.
While water is in the ground, it picks up soluble bits of whatever it passes through. While this can mean contamination that makes the water unfit to drink, in many cases it simply means that the water contains minerals found in the earth. Of these, calcium and magnesium are of particular importance because they affect the water’s ability to function in our homes. These minerals make our water hard.
One effect of hard water in California is that soaps and detergents lose some effectiveness. Instead of dissolving completely, soap combines with the minerals to form a coagulated soap curd. Because less soap is dissolved, more is required. And the sticky insoluble curd hangs around–it clings to the skin and may actually inhibit cleansing. Washed hair seems dull and lifeless.
In the laundry, things aren’t much better with hard water. The soap curd can work its way into your clothes as they’re being washed in your automatic washing machine. This can keep dirt trapped in the fibers, and it can stiffen and roughen the fabric.
In addition to affecting the actual washing process, insoluble soap deposits leave spots on everything you wash–from your dishes to the family car–and a soap film will build up in your bath and shower.
Another reason to be concerned about hard water is its effect on your plumbing system. Calcium and magnesium deposits can build up in pipes, reducing flow to taps and appliances. In water heaters, these minerals generate a scale buildup that reduces the efficiency and life of the heater.
Water Softeners are the Solution for Hard Water
Typical water softeners are a mechanical appliance that’s plumbed into your home’s water supply system. All water softeners use the same operating principle: They trade the minerals for something else, in most cases sodium. The process is called ion exchange.
The heart of a water softener is a mineral tank. It’s filled with small polystyrene beads, also known as resin or zeolite. The beads carry a negative charge.
Calcium and magnesium in water both carry positive charges. This means that these minerals will cling to the beads as the hard water passes through the mineral tank. Sodium ions also have positive charges, albeit not as strong as the charge on the calcium and magnesium. When a very strong brine solution is flushed through a tank that has beads already saturated with calcium and magnesium, the sheer volume of the sodium ions is enough to drive the calcium and magnesium ions off the beads. Water softeners have a separate brine tank that uses common salt to create this brine solution.
In normal operation, hard water moves into the mineral tank and the calcium and magnesium ions move to the beads, replacing sodium ions. The sodium ions go into the water. Once the beads are saturated with calcium and magnesium, the unit enters a 3-phase regenerating cycle. First, the backwash phase reverses water flow to flush dirt out of the tank. In the recharge phase, the concentrated sodium-rich salt solution is carried from the brine tank through the mineral tank. The sodium collects on the beads, replacing the calcium and magnesium, which go down the drain. Once this phase is over, the mineral tank is flushed of excess brine and the brine tank is refilled.
The Brains of Water Softeners
Most popular water softeners, like the Puronics Filtramax have an automatic regenerating system. The most basic type has an electric timer that flushes and recharges the system on a regular schedule. During recharging, soft water is not available.
A second type of control in water softeners uses a computer that watches how much water is used. When enough water has passed through the mineral tank to have depleted the beads of sodium, the computer triggers regeneration. These water softeners often have reserve resin capacity, so that some soft water will be available during recharging.
A third type of control uses a mechanical water meter to measure water usage and initiate recharging. The advantage of this system is that no electrical components are required and the mineral tank is only recharged when necessary. When it is equipped with two mineral tanks, softened water is always available, even when the unit is recharging.
Judging Water Hardness
West Coast Water Filtration is pleased to offer FREE in-home water testing. If you would like your water tested by one of our qualified technicians, please fill out our Free Water Test Form.
Water hardness is measured in grains per gallon (GPG) or milligrams per liter (mg/l, equivalent to parts per million, or ppm). Water up to 1 GPG (or 17.1 mg/l) is considered soft, and water from 60 to 120 GPG is considered moderately hard. A water softener’s effectiveness depends on how hard the incoming water is. Water over 100 GPG may not be completely softened.
Source: How It Works: Popular Mechanics