What is hard water?
Hard water is water that contains a high quantity of ions and minerals, such as calcium and magnesium. The hardness of water depends on the amount of these minerals present, and is measured in milligrams per litre (mg/L), or parts per million (ppm). The presence of these minerals causes the formation of scales and residue (such as soap scum or limescale). This kind of buildup is also known as fouling or scaling. Hard water is also resistant to soaps because it does not lather well.
What is a water softener and how does it work?
A water softener is a device that purifies hard water by eliminating the mineral content or reducing the adverse effects of the presence of these minerals. It has three main parts: a mineral tank, a brine tank and a control valve. The control valve allows hard water to pass through the water softener to be processed (or softened) before it reaches your taps. The water first passes through the mineral tank, which contains resins that trap the minerals that make your water hard. The purified water, or soft water, then flows into your house. The brine tank is full of salt water, which then passes through the mineral tank and cleans the resin of the minerals it trapped. This process is called regeneration. The resulting salty, mineral water is the waste water, which is pumped back through the control valve and drained from the water softener.
What is ion-exchange?
Ion-exchange refers specifically to the interaction between the resin in the resin tank and the magnesium and calcium ions in the hard water. Ions are simply molecules that have a positive or negative charge because of their atomic structure. Positive and negatively charged ions are attracted to each other, much like magnets. Resin beads are made of an insoluble polymer substrate and contain negatively charged sodium ions. Minerals such as magnesium and calcium ions are positively charged. The ion-exchange occurs when the positively charged ions in the hard water are drawn to the resin and exchanged with the negatively charged sodium ions.
What are the other methods of water softening and how do they work?
While most water softeners use the ion-exchange method, there are a variety of water softeners out there that can be used to meet your specific needs. Salt free water softeners use alternate methods such as electromagnetic waves or citric acid to reduce the adverse effects of hard water. Rather than eliminating the minerals in hard water, they simply interact with the minerals to reduce their scaling and fouling abilities. They are also referred to as water conditioners. Salt free water softeners are often smaller and require less maintenance, making them perfect for small households with water that is not extremely hard. Reverse Osmosis water softeners exist as well, and are best for removing specific chemical contaminants such as fluoride or sodium. Like salt free water softeners, reverse osmosis water softeners offer an alternative method of water softening for people with a different set of needs.