I'm a higher secondary school studet. See this following image, I can't understand how water can rises through the bed of permutit, my textbook says - Hard water introduced from the top of tank and then reaches at the bottom and then rises through the bed of permutit.!!, please tell me how it is possible.enter image description here

  • 1
    $\begingroup$ 1. Water pressure from the inlet, and 2. surface tension in the small pores of the zeolite both contribute in varying amounts. Most household softeners that I know of rely on the water pressure for most of the work. $\endgroup$
    – Jon Custer
    Sep 24, 2014 at 18:14
  • $\begingroup$ One thing that is not shown in the image is the water control mechanism. The tank can either be making soft water from hard water OR it can be being regenerated by pumping in salt water in the top and the waste salt water out the bottom. It can't do both at the same time. $\endgroup$
    – MaxW
    Feb 27, 2017 at 4:21
  • $\begingroup$ Can someone give a reasonable answer ? $\endgroup$
    – Ankit
    Dec 8, 2020 at 13:37

1 Answer 1


Hard water has minerals (mostly calcium and magnesium salts). The hard water is pumped into the coarse sand layer at the bottom. As the coarse sand settles, the water comes into contact with the Permutit zeolite. As the water rises through zeolite, it binds the calcium and magnesium and replaces them with sodium.


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