A Guide to Choosing a Water Softener

Choosing the right home water softener is more complex than you’d think, and there are lots of myths out there which can confuse people. There are so many key factors that you ought to consider. In this guide we’ll discuss everything that you need to think about; what makes hard water harmful? Why do you need a water softener? Where the home water system is stored, and ultimately what costs that you are facing

What makes hard water harmful?

First off, we need to look at why hard water is harmful. It ultimately can become rather disruptive to everyday household tasks and create a number of problems for you. This includes;

  • Damaging appliances and central heating system (and their efficiency)
  • Being difficult to clean
  • Causing problems for people with skin conditions such as eczema
  • Making washed clothes rougher

Your water is:

How does a water softener work?

An ion exchange, salt based, water softener tackles the problem of lime-scale by eliminating harmful minerals from the water before it has the chance to reach the taps. A water softener is connected to the home’s plumbing system, normally close to the incoming mains to ensure all parts of the home benefit from softened water.

An ion exchange water softener extracts the calcium (Ca) and magnesium (Mg) ions (lime-scale) found in hard water for harmless sodium (Na) ions.

  • Calcium and magnesium ions in water cause hardness so a water softener extracts them and replaces them with sodium ions.
  • In a process called regeneration, the resin beads are washed in a brine solution. This enables them to make more softened water.

The softening process adds a very small amount of extra sodium to the water supply, which in most cases is safe to drink. If you’re concerned, installing a water filter will reduce the amount of sodium in the water and improve its taste.

Graphical representation of the water softening process.
A graphical representation of the water softening process

Water softener design

All ion-exchange water softeners work on the same exchange principle. However, not all water softeners are the same. Research and development has greatly improved systems over the years, with manufacturers improving upon:

  • Durability and safety of the materials,
  • Improved control mechanism,
  • Ensuring water flows evenly within the resin bed,
  • Optimum water contact time for the exchange process, and;
  • The effectiveness and cost efficiency of the regeneration process.

Modern water softeners comprise a tank of resin beads, a brine tank (where the salt is stored), and a controller for the operation of the softener.

Methods of controlling a water softener

Time controlled

A timed controlled water softener goes through the regeneration process at specific intervals – it could be daily or weekly.

This could be wasteful because:

  • Regeneration may occur before the resin is exhausted
  • The regeneration process may not happen soon enough, leading to only hard water being available

Volume controlled

Volume controlled or metered water softeners, measure the amount of water flowing through the softener and regenerate the resin beads when they detect that they are exhausted.

For a meter controlled water softener to calculate when the resin has been exhausted it needs to know the hardness of the water and the amount of water that has been used. Therefore, a water softener set to the exact hardness of the water is going to be more efficient than a softener that uses a pre-set hardness range.

Electric water softener

An electric water softener is the most widely-used type of system. Electronic softeners – technology is used to record the water usage and control the regeneration process. A non-electric water softener relies on water pressure to measure the water use and operate the valves.

Single vs twin tank softeners (or block salt softeners)

The main differences between the two types of softeners are:

  • Single tanks offer on demand soft water v twin tank 24/7 softened water
  • Single tank electronic technology improves efficiency v twin tank non-electronic
  • Single tank is a simpler design with less component parts v twin tank complex design
  • Single tank for even water flow v twin tank can fluctuate water flow when in regeneration
  • Single tank softeners use tablet or granular salt v twin tank are designed to use block salt.

Comparison of Twin and Single tank water softeners
Comparison of Twin and Single Tank Water Softeners

The twin tank softener has two low softening capacity tanks, which makes them compact in design, but increases their complexity. Twin tanks are mechanical and offer no performance information.

On demand vs 24/7 softening

We don’t use water in our homes 24/7, but we do need the reassurance that softened water will be available on demand.

When a single tank softener regenerates only hard water is available. On the other hand, twin tank water softeners have two resin tanks and one will go offline when it needs to regenerate, so that soft water is supplied 24/7.

Therefore you need to ensure the water softener offers soft water on demand. This means the single tank softener will regenerate when water is not being used (normally the early hours of the morning), and it’s technology will ensure there is always plenty of softening capacity during the day for your needs, therefore soft water always available, but without the complexity of a twin tank softener.

The twin tank low softening capacity means the softener will be working harder and regenerating frequently. A twin tank softener for a family can be expensive to run and their frequent regenerations can disturb water flow and increase wear and tear.

Tablet vs block salt

Tablet, or granular, salt is available in 25kg or 10kg bags and readily available from various outlets. Block salt is available in 8kg bags is limited in availability and more expensive.

Having the right salt can help reduce the running costs of your water softener.

Choosing a water softener for your home

Before selecting your water softener, always ask yourself:

  • Is the design suitable to ensure your home’s water will be completely softened?
  • What is the water softening capacity of the system?
  • How much salt and water is used in the regeneration?
  • Is there any after sales service available?
  • How much are you investing?
  • What does the warranty cover?
  • Where can water softeners be installed?

A well-designed water softener can last well over 10 years. In fact, it’s quite common to find people with good quality water softeners over 20 years old. This and other water softener buying guides, or a trusted water softener expert can point you in the right direction. 

So how much does a water softener cost?

Water softeners range from hundreds of pounds to over a thousand pounds. Like choosing a car, all systems promise to get you from A to B but some are capable of doing this more reliably and efficiently than others, with innovative technology and attentive after-sales service.

Softening capacity and the type of salt used by the softener determines running costs.

The ongoing cost involved is the salt and water used in the regeneration process. Comparison tables of salt and water usage are meaningless without knowing the softening capacity.

Different water softeners will use different amounts and types of salt for regeneration.

Tablet and granular salt are available from various outlets, whilst block salt has fewer suppliers and is generally twice as expensive.

What size water softener do I need?

Many people will think about the physical size of the water softener, but it is the water softening capacity of the water softener (the amount of soft water created between regenerations) that really determines its suitability for the home.

A small sized water softener in a home that needs high flow rates will not provide the correct contact time for the ion exchange to work effectively and the home will not have properly softened water.

The volume of soft water that can be created is dependent on the volume of resin inside the softener and the hardness of the water in your area. Trustworthy manufacturers will show how much soft water can be created by their water softener, normally based on a UK average of 300 ppm water hardness.

How much water does an average household use?

Your water usage (a guide is 160 litres per person per day) plus the size of your home will determine which softener is best for you. A water softener with low softening capacity would be suitable for 2-3 people, but a low softening capacity in a home of 4 or more people will be expensive to run and because it will be working harder increase its wear and tear and longevity.

Water softeners and the flow of water in the home

Another concern of householders is whether their water softener will have a detrimental effect on the home’s water flow. High flow rates are often not required in most homes. Larger properties with direct feed systems, high flow rates become a consideration.

If your plumbing is a gravity-fed system, ie: water is drawn from a tank, a good quality water softener will have no effect on your home’s water flow, as the pressure is related to the height of your stored water tank (head of pressure).

Direct feed system

However, mega-flow and combi-boilers are direct feed systems that require higher flow rates, as they depend on the pressure of your incoming mains water. These higher flow rates are normally obtained by larger pipework in your home. If in doubt, ask the water softener manufacturer if the water softener is suitable for a direct-feed system.

Larger homes with plumbing above 22mm will require a softener specifically designed for larger pipework. A standard water softener offered with larger hoses will not create the water flow required in a larger house and the ion exchange process can be compromised because there is not enough contact time with the resin beads.


Choosing a water softener for your home can be tough. Luckily for you, if you have any questions, we are always happy to help – 01494 484 000.

We recommend having a home survey before buying a water softener. Our EcoWater dealers will be happy to carry this out, it is free of charge and without obligation.

Book a free home survey!

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