What is Water Softener Regeneration? – A Complete Guide

Salt-based water softeners require regeneration or recharging to work efficiently and treat the hardness in your water. But what exactly is this cycle and how does it impact the process of water softening?

Let’s breakdown what the regeneration cycle is and why it’s so important.

Why Does a Water Softener Regenerate?

While there are several types of water softeners and descalers, only the systems that use salt require regeneration. These systems work via ion exchange.

As the untreated water enters the resin tank, it flows over the resin beads, which are covered in sodium ions. The sodium ions are exchanged with the hardness minerals, which become trapped in the resin bed. The sodium, meanwhile, flows with the water which is considered softened.

How ion exchange works

This process occurs each time hard water enters the tank. Over time, the resin bed becomes completely covered in hardness compounds with depleted levels of salt. It loses its ability to attract and hold any more hardness minerals. When the resin comes to this stage, it requires cleaning to regain its efficiency, which is known as regeneration.

During this process, the resin bed is flushed with salt water from the brine tank. The ion exchange process occurs again, but this time in reverse. The wastewater gets flushed out of the resin tank and down the drain with the hardness minerals, while the sodium ions cover the resin. The resin is now clean and ready for another service cycle.

When Does the System Regenerate?

Potassium Chloride for water softener

Water softeners have a control valve which tells the system when its time to regenerate. Some models allow you to customize these settings, giving you greater control over the process, while others come with several pre-set regeneration cycles. However, there are two main types of regeneration which you need to know about:

  • Demand-initiated regeneration: This type of regeneration keeps a record of your water usage and automatically starts the regeneration cycle once the softener has treated a certain amount of water. This type of regeneration works according to your usage, which is more effective and efficient. You save water, salt and time by only sending the system into regeneration when it needs it.  
  • Schedule-initiated regeneration: This method of regeneration is based on time rather than usage. The valve is pre-set to initiate regeneration after a certain number of days and will be determined based on factors like your water quality, the size of your household, amount of water used and the size of the resin tank. The downside of this is that even if the water softener is not being used, the regeneration cycle will initiate automatically, thereby wasting resources.

How Regeneration Works

There are two main ways that a regeneration cycle can follow. These are:

Co-Current Regeneration Cycle (Downflow Brining)

The traditional co-current cycle flows in the same direction as the service flow, beginning at the top where the hardness minerals are most concentrated and moving downwards where there is less concentration of mineral ions. This flow results in constant exchanging and re-exchanging of ions as the hardness minerals become distributed throughout the resin bed, depleting the unused portion of the resin bed every time. The exiting brine will have lost its strength, and the salt in the bottom of the resin tank will be depleted. This system is inefficient and uses up more salt and water to complete. It’s like emptying your vehicle’s gas tank every time before filling it up.

Counter-Current Regeneration Cycle (Upflow Brining)

With the counter-current cycle, the cleaning occurs opposite to the direction of the service flow. The brine is pumped rapidly up the resin tank, starting at the bottom where the salt isn’t completely depleted. As the brine rushes up the resin, it exchanges the sodium ions with the minerals in the resin. The resin bed is flushed of all the minerals and replenished with sodium ions, with the weak brine leaving from the service water entrance. Because this cycle begins where the resin still contains salt, fewer ions are exchanged, and the salt is distributed more fairly. The counter-current cycle is more efficient, using up to 75% less salt and up to 65% less water.

Related Article: 5 Stages of Water Softener Regeneration

Regeneration – How Much Time, Salt and Water Does It Take?

Sodium Chloride for water softener

The amount of time, salt and water your water softener uses to regenerate will depend on several factors, including the unit’s capacity, the quality of your water, the strength of the salt and so on.

Time: In general, a regeneration cycle will take around 85 to 90 minutes to complete. During this time, the water softener stops treating hard water, and the water flowing into your home bypasses the water softener. This is why most water softeners are set to begin the cycle at 2:00 am. However, if you have a dual-tank water softener, the tanks regenerate alternatively so you’ll never run out of softened water. 

Salt: In general, a household of 4 people with average water hardness will use around 40 pounds of salt per month or around 9-10 pounds of salt per week. Water softeners can be adjusted to use more or less salt depending on your usage and preferences. The less salt you use, the more frequent your regeneration cycles may need to be.

Water: Regeneration requires a fair amount of water to thoroughly brine and rinse the resin bed. It can take up to 25 gallons per recharge, depending on a variety of factors. This is similar to the amount of water a washing machine uses for a load of clothes.

How Often Should My Water Softener Regenerate?

Installed water softener

A water softener regenerates as often as it needs to, depending on whether the system initiates based on demand or a timer. We’ve already discussed the differences between schedule-initiated and demand-initiated cycles above but on average.

For the average household, a water softener would run a regeneration cycle every 3-6 days. Some important factors that impact the frequency of regeneration are water hardness level, water usage, size of the resin tank and quality and amount of salt.  

The Bottom Line

Regeneration is one of the most technical and important aspects of the entire water softening system, required for the system to perform at its best. Always ensure that there is sufficient salt in the brine tank and choose the best salt for the job for best results.

Water softeners aren’t cheap to maintain as they require ongoing costs and maintenance, but they’re well worth the effort for the benefits that they bring.

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