Water softening basics
Water, passing through the atmosphere as snow or rain, picks up carbon dioxide (CO2) and other acid gases and reaches the Earth's surface as a weakly acidic solution (CO2 + H2O -> H2CO3) known as carbonic acid. The rain that falls into the surface waters such as streams, rivers, ponds and lakes is normally low in dissolved solids and hardness.
As this water soaks in, it passes through various strata containing limestone (CaCO3), which neutralises the acid forming a soluble calcium bicarbonate salt (H2CO3 + CaCO3 -> Ca(HCO3)2.
This then dissociates into ions: Ca++ ions with a plus 2 positive charge is a cation and HCO3- with a single negative charge contributes two anions. This is how calcium (and magnesium) end up in the water supply. When calcium and magnesium levels are high, water is described as being "hard".
When hard water is heated, the Ca(HCO3)2 decomposes to CaCO3 and evolves CO2 gas and H2O (water). CaCO3 is insoluble and deposits on the surface of water heaters, often found in boilers, coffee makers, pipes, on to fabrics, creating a hard scale (known as calcite, limescale, boiler scale or hardness scale). This scale is a poor conductor of heat and so it takes more energy to heat water if the heater element or boiler tube is covered in scale. Scale can also clog pipes and appliances and reduces the life of fabrics due to abrasive nature. In addition, when washing, the soluble calcium and magnesium salts will react with the soap causing the familiar bathtub ring and soap scum. It is desirable to remove hardness ions before using the water in residential and industrial applications.
Ion exchange is the preferred process for removing hardness ions. In domestic applications, low level hardness is acceptable. In industrial applications particularly boilers, hardness has to be removed.
The dangers of limescale
Limescale build-up in heating systems causes a loss in heating efficiency, wasting energy
Showers, washing machines and immersion heaters become damaged and inefficient more quickly
Limescale quickly builds up on taps, sinks and other fittings becoming unsightly and making cleaning difficult
Hard water can aggravate skin conditions such as eczema
Ion exchange was first recognised by Thompson and Way in 1858 who observed that when ammonium salt was poured through the soil, the water trickling out from the container had a different composition. the soil captured ammonium ion and released sodium. Natural soil contains clay and zeolites that have ion exchange capabilities. By order of selectivity, multi-valent ions are grabbed by ion exchangers, which will then release a less tightly held, more desirable ion. It should be noted that mono-valent ions such as sodium or potassium do not cause scale and do not react with soap.
Zeolites were synthesised in 1903 to offer higher capacity and stability than the natural zeolites. in 1905, German industrial pioneer Robert Gans commercialised the first regenerating ion exchanger for hardness removal. Synthesis of new chemistry gradually improved the efficiency of the softener through the 1940's when G.F. D'Alelio of GE produced the first suspension polymers of styrene and di-vinyl benzene (S/DVB), giving birth to modern ion exchanger.
The basic chemistry of softener resins has remained unchanged since that time. Ion exchange softening systems use reactive plastic polymers beads with chemical functionality that selectively captures the di-valent ions such as calcium and magnesium and releases less tightly held mono-valent ions, normally sodium.
Benefits of soft water
Save up to £400 a year!
Use up to 75% less detergent, washing powder soap and shampoo that could save you up to £400 a year.
Better for the enviroment
Spend less on your heating bills, less pollution made from factories.
Alleviate Eczema and dry skin
Eczema and dry skin will both respond positively to softened water. This is due to the softener removing the calcium and magnesium present in hard water which is what irritates the skin.
Increase the lifetime of appliances
Washing machines and dish washers work longer with soft water preventing limescale building up within the machine. Saving you pennies in the long run.
Softer, brighter looking clothes
Softened water removes residual impurities leaving your clothes feeling softer and looking vibrant for longer.
Smoother skin and silkier hair
Enjoy the everyday experience of having a water softener, with smoother and brighter skin and silkier hair
Spend less time cleaning
Keep your tiles and shower-screen free from limescale and banish water marks from taps and toilets.
More bubbles, less bubble bath.
Softened water encourages soap lather to form so less soap and shampoo is needed to create the same effect.
Soft water can reduce the damage of eczema. This is due to calcium and magnesium being removed from the water and preventing contact with your skin. Despite various studies showing no link between the two, people with eczema are amazed by the effect of a water softener. So if you or a family member suffers from eczema, why not try a water softener?
Kings College London are currently running a blind controlled pilot study of an ion-exchange water softener for the prevention of atopic eczema in neonates. We will keep you posted with the results.
Damaging effects of hard water
People with eczema might find their skin improves when they install a water softener or move to a soft water region. This is because hard water contains high levels of calcium and magnesium which can potentially irritate the skin by damaging our protective skin barrier.
Another reason is that households in hard water areas tend to use more soap and detergent when washing clothes and bathing – products we know inflame the skin of eczema sufferers. Water softeners have an ‘ion exchange’ system which removes the calcium and magnesium salts from the water, thus completely eliminating the hardness.