How Does a Water Softener Work

How Does a Water Softener Work?

A water softener is a device that is connected to your home’s water system. It works on a principle called “ion exchange”. This trades the minerals in hard water for something else.

TERM - Ion Exchange: The process of removing “hardness ions” from the water (usually calcium or magnesium but sometimes iron as well) and replacing them with “softer” ones, typically sodium.

Water Softening

Ion exchange systems have a control head that connects to your water main. Under normal use, this head directs the water through the media tank. Water goes through a tube to the bottom of the tank, then moves upward past salt-saturated media. Calcium and magnesium ions swap places with the salt ions. The water leaving the media tank is soft and slightly salty.
 
For every GPG of hardness, or every 17 mg/L, this exchange adds about 0.2 mg of salt per ounce of water. Even if you have the hardest water in America, this process only adds 4.6 mg of salt per ounce. If all the water you consume had this amount of salt in it, it would only be about 6% of your daily salt intake. You won’t notice much of a taste difference, but the water will feel slicker than hard water.
 
The media also attracts iron ions. This is useful for removing small amounts of iron, but it can easily overwhelm the system. The bond between iron and the filter resin is stronger than the bond between the resin and salt, calcium or magnesium. Rust removers must be used as a regular part of maintenance. If you have high levels of iron in your water, it needs to be removed before the softening stage of your water treatment system.

Softener Regeneration

Eventually, the salt in the tank is used up, leaving the media coated in hardness minerals. Ion exchange systems regenerate the media using brine. The system has a separate brine tank that holds salt. Pre-fill systems add water to the tank a couple of hours before the regeneration cycle, while post-fill systems always keep water in the tank. Brine from post-fill systems is saltier, so it does a better job regenerating the media. However, this gives the salt more time to fall out of suspension, forming salt bridges that can block up the tank.
 
Mechanical heads trigger a regeneration cycle based on water flow or time. Electronic heads measure water flow, then wait until low usage hours, typically early in the morning, to run a regeneration cycle. There are four steps in this cycle:

What Happens Next?

Now that the beads are fully saturated with hardness ions, they can no longer soften any new water. That’s where the second tank comes into play. The “brine tank” makes the water in the resin tank salty again by flushing the resin tank with salt brine. This washes away the hardness ions and replaces them with new sodium ions. The device is now ready to start softening more water.

Here’s the water softening process at a glance

Here’s the water softener regeneration process at a glance

Once the fast rinse is finished, the head moves the valves back to their normal operating system. Post-fill systems fill the brine tank with water. The entire regeneration cycle takes around 90 minutes.

How Water Conditioners Work (TAC)?

TAC water conditioners (salt free) have a single tank and a head that connects to the plumbing system. Unlike ion exchange systems, conditioners don’t have a regeneration cycle. The valves on the head are there to let you bypass the system when you need to service the media tank.
 
If you’ve ever made rock candy in science class, you’re familiar with crystallization. Rock candy forms when sugar dissolved in water attaches to solid sugar on a stick or piece of yarn.  This undissolved sugar acts as a nucleation site, kicking off the bonding of dissolved sugar molecules, forming crystals.
 
The tank contains polymer beads that act as a nucleation site. Hardness minerals attach to the surface of the media, then molecules attach to these seeds, forming crystals. Eventually, the crystals get too big to be held in place by the electric charge of the media and flake off. The water is still hard, but these microscopic crystals are inert, so they don’t form soap scum, and won’t leave scale behind on plumbing and appliances.
 
Crystallization also releases microscopic carbon dioxide bubbles. These bubbles scrub scale off the insides of pipes. This raises the hardness of water until the pipes are clean. If you install a TAC conditioner in an older home that hasn’t had a water softener before, this process can take up to three months.

How Magnetic Water Conditioners Work?

Electromagnetic water conditioners (salt free) send electricity through a large copper winding that wraps around the water pipe. This magnetic field negates the charge of magnesium and calcium ions for up to 72 hours. In this state, these molecules don’t leave deposits on plumbing and appliances.
 
Magnetic water conditioners are common in industrial settings where huge volumes of water are processed before heading to boilers. However, the size and power required for these conditioners makes them impractical for most home water treatment. A whole house system requires large amounts of electricity sent through several feet of thick copper wire to be effective.

Smaller systems that target the line going to a specific appliance are more practical, but this leaves you with hard water problems in the rest of your house. Permanent magnets aren’t strong enough to be effective at neutralizing minerals.

Salt-Based or Salt-Free Softener?

There’s an ongoing debate amongst businesses and homeowners whether a salt-based or a salt-free water softener is best. The issue is that most people think it’s an issue of preference—if you don’t like the taste of “soft” water, then there’s nothing wrong with switching to a saltless water softener.

This is wrong. And there are certain instances where you need a salt water softener or your home will still be at serious risk.

Here’s why:

When You Need a Salt-Based Softener

There are times when a saltless softener won’t cut it. Even if you don’t like the taste of soft water, you just need to deal with it. This is when your mineral content is very HIGH. If you have high hard water levels, you need a salt softener.

Most companies offer testing equipment to measure the hardness of your water. It’s done so in terms of grains per gallon (GPG). Anything within the range 60-120 GPG is considered moderately soft. If you are at the top range (100+), then a salt-based softener is recommended.

If the taste of the water or your sodium restrictions are that much of an issue, you can have a plumber reroute some of the water or install separate water filters on your taps to make the water better to drink.

Now that we’ve answered the question “how does a water softener work”, you need to find the best water softener on the market for your home.

What is Hard Water, and Why is it a Problem?

Water is a powerful solvent that picks up minerals as it passes through the water table. If the water passes through chalk, gypsum or limestone, it picks up calcium carbonate, magnesium carbonate, sulfates and bicarbonates. Water with a high mineral content is “hard” water.
 
Hard water isn’t a health hazard. In fact, it provides a source of calcium and magnesium. However, the minerals in this water leaves deposits in plumbing and appliances. Over time, this clogs pipes, requiring costly repairs. Appliances that heat water, including water heaters and clothes washers, are particularly susceptible to scale buildup.
 
The minerals in hard water also react to soap, forming soap scum. This limits the effectiveness of the soap, and the resulting calcium stearate leaves hard-to-clean deposits around plumbing fixtures. It also makes soaps and detergents less effective, and can leave your skin feeling dry after a bath or shower.
 
Water hardness is measured by milligrams of calcium carbonate per liter (mg/L) or grains of calcium carbonate per gallon (GPG.) Hardness is divided into four categories. Here’s what you can expect with each category of hardness:

Soft Water : 0-60 mg/L, 0-3.5 GPG

60 million Americans live in households with hard water. Much of the Western U.S, Illinois, Ohio and parts of upstate New York have hard water, although mineral deposits can increase water hardness locally. The highest mineral content ground water in United States a hardness of 340 mg/L (19.9 GPG.)