Limescale Filters Explained Re January 5, 2022

Limescale Filters Explained

Heating engineer fitting a boiler

Limescale build-up can become a big issue if not sorted. You’re daily appliances like your kettle or your luxury coffee machine can get clogged up. Yes, that means no coffee!! Your new, gleaming glasses can get tinted and become difficult to clean, and even your shower head can get blocked. 

This is why it is recommended that you keep on top of removing limescale from your water. This article will explore what limescale is, potential health issues with limescale and different types of limescale filters to help keep your water fresh and clean.

What Is Limescale?

Limescale is a hard white crust that forms inside kettles or on taps in hard water areas. This residue is left behind when hard water is left to stand and evaporate.

Soft water contains fewer impurities than hard water because it runs through rock such as granite or slate, while hard water runs through porous rock such as chalk and limestone, picking up minerals that form limescale.

When hard water is heated or left to stand, the dissolved minerals in the water solidify and form limescale. Hard water is filled with minerals including calcium, carbonate, magnesium and manganese, which are not necessarily bad for you, however, they contribute to the poor taste you get when drinking the water. Statistics reveal that 85% of European and similarly 85% of US homes are affected by such issues.

Why You Should Remove Limescale

Limescale can cause problems in a number of areas in your home, from minor to major issues. Below is a list of common problems caused by hard water and limescale:

  • Blocked heating pipes, showerheads and taps.
  • Loss of water pressure due to the reduced pipe diameter.
  • Bacterial growth in drinking water pipes.
  • Frequent repairs or replacement of household appliances such as kettles and washing machines.
  • Replacement of heating pipes.
  • Irritation of sensitive skin.
  • Dry and dull hair.
  • Loss of energy in the hot water systems and increased heating costs.
  • Less effective detergents, resulting in clothes that look dirty even after being washed.
  • White residue and dull surfaces in the bathroom and kitchen.

When hard water makes its way through the mains and into our homes for cooking, cleaning, washing and heating are when problems can arise. Millions of people in the UK receive hard water through the mains water supply with London having particularly large areas with hard water. When hard water molecules are agitated (warmed up) in kettles, dishwashers and any home appliance the hardness can precipitate as limescale.

Limescale build-up is not something you want in your home for numerous reasons including blocking and damaging pipes, reducing the effectiveness of breaking household appliances including your boiler. 

On the topic of boilers, there are other factors that could be affecting the efficiency of your boiler such as a build-up of sludge and debris in your central heating. If you are experiencing these problems, we have separate blogs on how to prevent this issue from happening, such as a system cleanse or a power flush, in more serious situations, and how a magnetic filter could also help. 

According to new research from online articles, limescale could be costing households in hard water areas an extra £180 a year on heating. 

Approximately half of UK households (a total of 13 million) currently suffer from hard water. Households in these areas can accumulate 1.5mm of limescale within their internal plumbing over a year, which can increase average gas costs by 28%.

Research demonstrates that limescale build-up can cause a significant strain on finances for many households, particularly with the current climate meaning that more people are spending the majority of their time at home. 

Limescale deposits within heating systems can cause blockages in pipework and boilers, reducing heating efficiency by 12% over a year. So how can we prevent this?

Water softeners draw out the magnesium and calcium ions which make water hard and limit the accumulation of scale and scum, preserving the efficiency of heating systems. It is said by Wales Online that UK households spend on average £12.30 a week on fuel. As a result of this,  households in hard water areas could save a combined total of £2.3 billion a year by switching to a water softener. For more information on water softeners, keep reading 😉.

How To Know If I Have Hard Water In My Area

We have attached below a map of the UK, which shows which parts of the country is classed as soft water areas as well as hard water areas. 

If you would like specific information regarding the chance of limescale build up in your area, you can visit

What Is A Water Softener?

A water softener system attaches directly to the mains water supply. It works by passing the water through the system, stripping the hard water particles from the water. It then releases the softened water back into the ongoing water supply. 

Water is one of the most important substances on the planet, covering over 71% of the Earth’s surface. Water is vital to a huge number of applications including agriculture, heating, washing and most importantly, drinking.

For the majority of us, drinking water comes from a treated municipal supply that is safe to drink. However, you may often experience a bad taste or odour in water with chemicals such as chlorine, which is often used to disinfect water, keeping it free from germs and bacteria. In addition to this, depending on where you live, you may also find that your mains water causes limescale deposits to form which can block pipes and damage appliances. These issues, chlorine taste/odour and limescale formation are just two among a host of other common water problems which can be solved by water filtration and softeners.

How Do Water Softeners Work?

Water softeners work through a process called ion exchange which eliminates calcium and magnesium from the water. When the hard water enters the mineral tank, it flows through a bed of spherical resin beads. These plastic beads that are typically made from polystyrene, are charged with a sodium ion. The resin beads are anions, meaning they have a negative charge. The calcium and magnesium minerals have a positive charge, making them cations. 

Since opposite charges attract, the negative charge of the minerals is attracted to the positive charge of the resin beads. As the hard water passes through the resin, the beads grab ahold of the mineral ions and remove them from the water. When the bead seizes the mineral ion, the sodium ion is released. The column of resin strips all the hardness out of the water as it passes through the mineral tank, and softened water flows out into your home. 

Yes, we know, all that chemistry can be a lot to take in, so in basic terms, water softeners remove the hardness-causing calcium and magnesium minerals from your water, preventing limescale.

What Are The Components Of A Water Softener?

A water softener is made up of three components: a control valve, a mineral tank, and a brine tank. These three work together to remove the minerals from hard water, monitor the flow of water, and clean the system through a regeneration process. 

1. The mineral tank

The mineral tank is where the magic happens; the chamber where the hard water is softened. The water supply line feeds the hard water into the tank. The water seeps through the bed of resin beads which is where the water-hardening calcium and magnesium ions are deposited. The water exits the tank soft and flows through your pipes and out to your household appliances.

2. The control valve

The control valve measures the amount of water passing through the mineral tank and into your house. The control value has a meter that tracks the volume of water entering the mineral tank. As hard water flows through the mineral tank, the resin beads exchange their sodium ions for hardness ions.

Over time, this depletes the capacity of the resin to continue to effectively soften water. Before the beads become too burdened with mineral content to continue removing calcium and magnesium ions, the control valve automatically initiates a regeneration cycle.

3. The brine tank

The brine tank helps the water softening system in regeneration. It is a shorter tank that sits next to the mineral tank. The brine tank holds a highly concentrated solution of salt (or sometimes potassium) to restore the resin beads’ positive charge.

Blocks or pellets of salt are manually added to the brine tank. These dissolve in the water at the bottom of the tank. When the control valve registers the softening capacity of the resin is reducing, the heavy brine solution is drawn out of the tank and flushed through the resin in the mineral tank. If the brine tank runs out of salt, the water passing through the unit will no longer be softened.

Do I Need A Water Softener?

If you’re living with decreased pressure from limescale filled pipes, dried out hair, stiff and uncomfortable laundry, and endless appliance repair bills, you probably need a water softener. Hard water is not a problem that will go away on its own and the costs incurred by hard water will only continue to escalate if not prevented. Without a water softener, appliances will inevitably fail sooner than their expected lifespan.

If limescale continues to accumulate in your pipes, your flow rate will continue to restrict and you risk losing water pressure throughout the house. 

Choosing the right size softener depends on a number of things. To make it simple we have categorised our domestic softener range into the following options depending on how many people live in the household. We have added a list below to make it a little easier for you to identify what capacity of water softener you need for your home:

  • 1-2 Person Compact Premium Household Water Softener (5 Litre)
  • 2-4 Person Compact Premium Household Water Softener (10 Litre)
  • 2-4 Person Premium Household Water Softener (10 Litre)
  • 4-5 Person Premium Household Water Softener (14 Litre)
  • 5–6 Person Premium Household water Softener (18 Litre)
  • 7+ Person & Commercial size Premium Water Softener (23 Litre)

What Are The Different Types Of Water Softeners?

Non-electric water softeners

Non-electric water softeners are powered purely by the incoming water pressure, making them extremely easy to install. What makes them even better, is that they won’t have an impact on your monthly electricity bills either! 

Non-electric water softeners are generally thought to last longer and to be more reliable. A twin tank version will offer you an unlimited supply of softened water at all times of the day and night.

Metered water softeners

Metered water softeners only regenerate when a certain volume of softened water has been used, no matter how long that takes, making them highly efficient and possibly the most economical water softener when it comes to regenerating and using salt.

Time clock water softeners

These are very basic water softeners, functioning on a timed basis. The clock is set so that the water softener regenerates on specific days, often at 2am. This is regardless of the amount of water used.

How Much Does A Water Softener Cost?

There are a number of factors that can have an effect on the price of your water softener, including:

  • The Brand
    Water softeners from well-known brands often cost more, but they also tend to be more reliable.
  • The Size
    Water softeners that have a higher capacity are usually more expensive. When working out what size you need, you’ll need to take into account things like the amount of water that needs to be softened and the hardness level in your area.
  • The Type
    There are lots of different types of water softeners, including ones that don’t use any electricity.

How Do I Install A Water Softener?

A water softener should be installed as close to the water’s point of entry into the house as possible. This ensures the majority of your plumbing and appliances are reaping the benefits of carrying the softened water.

It’s especially important to make sure your water softener is located before your water heater, as hard water does the greatest damage to hot water appliances.

When installing your water softener, it is important that you choose a dry, level place, like your garage. It will need to be close to the water’s mainline, an electrical outlet to turn on the system unless you have a non-electric water softener, and a drain for the brine solution from the regeneration cycle.

Steps to installing your water softener: 

  • Position the water softener. Make sure that the softener is correctly positioned. The inlet should be connected to the water supply and the outlet should be facing the direction of the hot water appliances. 
  • Turn off the water supply to your house at the main line. This will help prevent any leaks whilst installing. Make sure your water heater’s water supply and electricity running to the unit is turned off.
  • Drain your pipes. Open nearby faucets or faucets on the bottom floor of your home to ensure all water exits your house’s supply pipes.
  • Cut into the water supply main line. Using pipe cutters, cut into the water main leading into the supply line. This is a whole house filtration unit, so you need to connect the inlet and outlet lines directly to the water main line. 
  • Measure, cut, and connect the pipes. Before attaching any pipes to your water softener, measure and cut your pipes to fit. If you are using copper pipes, solder on any nipples and fittings before connecting the unit to the bypass valve to avoid melting the plastic. Seal all threads with plumber’s tape. Plastic tubing like PEX can also be used.
    You may need additional adapters for this part. Flexible tubing is far easier to work with and can utilize push-to-connect fittings, saving you time and the hassle of soldering. 
  • Clamp the drain hose. The water softener needs to drain the depleted brine solution after the regeneration cycle. Clamp the drain hose securely and feed it into the dedicated drain, like a floor drain or utility sink. To prevent the hose back siphoning waste water, all drain hoses must have an air gap. The end of the hose be at least two inches above the dedicated drain. An air gap may be used to achieve this, and may be required depending on local plumbing codes. 
  • Connect the overflow tube. Overflow tubes are an additional precaution ensuring the brine tank does not flood and overflow. Refer to the manufacturer’s instructions for specific placement of this hose. The overflow tub may also require an air gap.

When Do I Need To Replace My Water Softener?

Water softeners typically have a lifespan of 15 years, however, water softener systems can last much longer if they are properly maintained. Making sure the brine tank never runs out of salt will extend the unit’s life.

Protecting the resin bed from high levels of iron and manganese will also protect the unit. Resin can last for 10-20 years as long as it is maintained well. Iron will foul the resin and lower its ion exchange performance. Resin cleaners enhance the regeneration cycle and help relieve the resin beads of hardness-causing minerals.

It is wise to place a sediment filter in front of your water softener, especially if you are on well water with lots of dirt and debris. If you live with extremely hard water, your system may not last as long as someone softening moderately hard water. 

The variance of factors make it difficult to determine a specific time frame for replacing a water softener. If your unit is over 10 years old and you notice that its softening powers are not as efficient then it may be time to invest in a new system. 

We hope that this blog has helped you understand the cause of limescale build-up and what you can do to prevent it. If you need additional help, you can always hop on to our live chat where a member of the WarmZilla team can assist you further.


Limescale is a hard white crust that forms inside kettles or on taps in hard water areas. This residue is left behind when hard water is left to stand and evaporate.

A water softener system attaches directly to the mains water supply. It works by passing the water through the system, stripping the hard water particles from the water. It then releases the softened water back into the ongoing water supply.

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