You have probably come across the terms “soft water” and “hard water” and wondered what they mean? Why do we need to soften the water used in our homes?
While other articles on this site, focus on picking the best water softener with specific reviews, this article will answer the question "how does a water softener work?"
To understand the concept of water softening and its advantages, we must first learn about the types of water. Depending upon the amount of dissolved minerals in our water, we have two types of water: hard water and soft water.
Dissolved minerals such as magnesium and calcium are picked up by the water when it passes through the soil and rock underground. The concentration of minerals in the water determines the hardness of water. If there is a high concentration of minerals in a gallon of water, it will be called hard water compared to a gallon of water with only a few minerals.
Hard water is not harmful but it is undesirable because it can clog pipes and reduce water flow.
Hard water also causes problems when used in daily tasks around the home such as cleaning dishes, bathing or laundry. Hard water does not form enough lather and usually leaves a sticky scum when it comes in contact with soap. This makes washing off soil and bacteria difficult, and leaves the skin and hair feeling dry and dull.
Washing laundry with hard water doesn’t completely clean the clothes and can damage clothes in the long run. It is preferable that household water doesn't contain these minerals. The process of removing these minerals is known as softening of water.
How does a water softener work?
The hardness of the water is due to minerals like calcium and magnesium saturating the water. The act of softening of water is removing these minerals.
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Water softeners work on the principle of ion exchange where the harmful minerals are replaced with another mineral. In the case of salt based water softeners, these minerals are replaced with sodium.
A water softener is a mechanical device that is attached to the household water supply system where the water enters the home. After exiting the water softener, the soft water is then sent to the different water faucets in the home.
A water softener consists of a softener tank which has thousands of tiny resin beads or zeolites, which are basically polystyrene beads. The resins are coated with sodium positive ions. The resin beads attract and bind the magnesium and calcium ions present in hard water.
Calcium and magnesium have a positive charge and they switch positions with the sodium ions on the resin bead as water is pumped through the beads. Water coming into the softener has calcium and magnesium minerals. Water exiting the water softener will have sodium ions..
After some time, the beads are saturated with calcium and magnesium and the water exiting the water softener is hard again. To remove the calcium and magnesium from the resin beads, a regeneration cycle is required.
A strong saltwater (brine) solution (created using common salt in a separate brine tank) is used to wash away the minerals collected by the beads. Calcium and magnesium ions are displaced by the high concentration of sodium ions in brine solution, and the resin gets coated with new sodium ions. The salty rinse water, and the minerals are flushed down the drain and a cycle has been completed. This is known as recharging of the resin, and the process is repeated every few days.
Trigger a Recharge Cycle
The process of recharging can be controlled in a variety of ways.
The most common method is the use of electric timers which automatically flush away the rinse water and minerals through the drain on a fixed scheduled time.
The second method is to use an electronic device or mechanical meter to measure the amount of water usage. The device starts the regeneration process once the set amount of water has passed through the mineral tank.
Salt or salt less?
There are some arguments against salt-based water softeners.
The main argument is that minerals like magnesium and calcium are healthy and beneficial to us and they are being replaced by sodium. Sodium can be harmful to both our health as well as the environment.
Also, the cost of maintenance can be high, and the cost of buying salt must be factored into your budget.
Water softeners have been developed which do away the use of salt completely, and these are the salt-less water softeners. Technically they don’t soften the water because the hard minerals aren’t removed from the water. Instead they are crystallized so they don’t adhere to the surface of clothes or utensils as they did before.
The term water conditioners or descalers is used to describe these devices instead of water softeners. They use either magnets or electrical current carrying wires for the process of conditioning.
Usually permanent magnets are fixed to either the inside or outside of water pipe. The magnetic field produced by them crystallizes the minerals.
Another alternative is using an electromagnet - an electrical current carrying wire - around the water pipe which performs the same function as the magnets.
Although salt-less water softeners are cheaper and easier to maintain than salt type water softeners, studies suggest they aren't as effective.
Many people argue that the laundry done is not as soft and the whites aren’t as white when salt-free water softeners are used.
The use of salt-less water softeners is limited to an extent and softeners with salt are primarily in use everywhere.
In many areas, water softeners are a necessity because of the issues caused by hard water if not treated properly.
We have discussed "how do water softeners work" with an overview of removing the problematic minerals magnesium and calcium that build up over time. This "scale" is what you're trying to prevent.
These minerals don’t form lather easily and therefore mess up the cleaning process.
More importantly, they cause buildup of scale in water pipes which if not treated at the earliest would become a huge issue in the long run. The replacement of pipes would result in huge costs and inconvenience.
It is important to invest in good water softening equipment and there are two main options available.
One uses salt such as sodium in the recharging cycle of resin beads.
The second is a salt-free water conditioner that is popular due to concerns related to sodium intake and is a cheaper alternative. It uses either magnetic or electric fields to neutralize the minerals. It also has a much simpler set-up and is less costly (no monthly salt purchases).
As is the case to every technology, there are pro and cons to every alternative.
Water softeners with salt are preferred because of their reliability and efficiency.
Ultimately it comes down to the preference of each individual but this article has given an overview of the different types of water softeners. For a more detailed look at water softener options, look at our best water softeners reviews page.