Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers


Water Softening

Last updated: November 30, 2020

What Does Water Softening Mean?

Water softening is a process through which calcium, magnesium and certain other metal cations in hard water are removed.

Water softening is an important process, because it can extend the lifespan of household appliances and pipelines, as well as improve function and lifespan of solar heating systems, air conditioning units and many other water-based applications.

Hard water contains significant amounts of calcium and magnesium ions, which can clog pipes and complicate the dissolving of soap and detergent in water. Water softening can prevent these negative effects.


Corrosionpedia Explains Water Softening

Water softening is the removal of calcium, magnesium and certain ions in hard water. The resulting soft water is more compatible with soap and extends the lifetime of plumbing and appliances.

Hard water causes a higher risk of lime scale deposits in household water systems, which can foul plumbing and promote galvanic corrosion. This increases the cost of domestic water heating by about fifteen to twenty percent. Another negative effect of lime scale is that it has damaging effects on household machinery, such as washing machines. In industrial-scale water softening plants, the effluent flow from the regeneration process can precipitate scale that can interfere with sewage systems.

Water softening is usually achieved using lime softening or ion-exchange resins or reverse osmosis. Other techniques include precipitation methods and sequestration by the addition of chelating agents.

Advantages of water softening include:

  • Removal of iron, manganese and radioactivity
  • Reducing tastes, odors and total solids content
  • Lime softening can aid in disinfection
  • Avoidance of corrosion in the distribution system by using recarbonation at the end of the lime-softening process

However, lime softening tends to favor the formation of hypochlorite as the dominant free chlorine residual, which may produce corrosive water and corrode the distribution system. Additionally, both lime softening and ion exchange softening create waste disposal problems.



Water Softener

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