Discover How Home Water Softeners Work

Understand and Choose Home Water Softening Systems

Home water softeners are appliances that use a process called Ion Exchange to remove minerals dissolved in hard water.

Some of the minerals that can be a problem in hard water are calcium, magnesium, iron and manganese.

Water softeners exchange the mineral content present in the water source for sodium ions, making the water soft in the process.

Home water softeners have four integral components:

  • Softener Valve - Controls the water as it flows through the valve, resin bed, the distributor / manifold and brine tank
  • Resin Tank - Holds water softening resin and gravel under-bedding
  • Resin - Small beads that hold the sodium "charge"
  • Brine Tank - Holds salt and water used to regenerate the water softening resin

The Water Softening Process

As hard water (calcium and magnesium ions) enters the softener valve it is diverted to the resin tank, hard water flows through the "resin bed" and comes in contact with the resin beads.

The resin beads are "charged" with sodium ions. As the hard water flows through the resin bed calcium and magnesium ions are attracted to the resin beads and the sodium ions are exchanged. Removing the hard water minerals and delivering "soft water" to the home.

The resin bed has a certain amount of "capacity" and has to be recharged / regenerated with sodium or potassium chloride before it is completely depleted of "soft water".

How a whole house water softener worksThis image explains how the water softening process works in a whole house water softener.

In general terms the resin beads are much like a large sponge and can only attract or hold a certain amount of hard water. The sodium is what's used to squeeze the sponge so it can absorb again.

When a sponge becomes too saturated it gives off water. A home water softener has to avoid leaking off hard water so it regenerates before it becomes totally saturated with hard water minerals.

One full day of soft water is left in reserve for days with higher than normal water usage or times when the normal capacity may be reached first thing in the morning and the system is set to not regenerate (delayed regeneration) until that evening at 2am.

This is referred to as the reserve capacity.

The Regeneration Process

When the predetermined "capacity" is reached the water softener will regenerate. Some systems may differ in their sequence of cycles. This is the most prevalent regeneration process used.

Regeneration Cycles:

  • Backwashing - Reverses the flow of water through the distributor/manifold to clean the gravel under-bedding at the bottom of the resin tank, lifts/loosens the resin bed and washes out oxidized particulates
  • Brine Draw - A concentrated brine solution is drawn from the brine (salt) tank and washed through the resin bed displacing the hardness minerals from the resin beads, flushing them to the drain and recharging the resin beads with sodium or potassium. (This cycle may be either down-flow or up-flow through the resin tank depending on the model)
  • Slow Rinse - A slow rinse to rinse off excess sodium that may be present in the resin bed
  • Fast Rinse - Down-flow of water to compact resin bed and prepare for service
  • Brine Refill - Refills the brine (salt) tank with the proper amount of water to dissolve sodium or potassium and prepare brine solution for next regeneration cycle. (This may be the initial cycle or last cycle in some systems)
  • Service - Normal operating position for daily water usage

Types of Water Softening Systems

There are five types of home water softeners:

  1. Manual - Manually regenerated by homeowner
  2. Portable Exchange - Regenerated off site by dealer
  3. Time Clock - Regenerates according to days a week (6-14 day timer)
  4. Demand/Metered - Regenerates according to gallons used
  5. Twin-Tank Demand - Two tank system. One softener tank is in service and one in standby mode. Tanks switch during regeneration
Benefits of using a water softenerBenefits of using a water softener

How to Choose and Size Your Home Water Softener

There are several important factors to choosing the proper water treatment system for your home and family:

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  • Water analysis - Determines the total hardness (calcium, magnesium), Iron (how much, what type), PH, TDS, H2S and others
  • Water Usage - Average daily water usage for your household. Most families average 75 gallons per day per person. 4 people x 75 = 300 gallons per day usage
  • Fixture count / GPM - In many modern homes the Gallons Per Minute needed to operate a home are critical and needs to be part of the equation in sizing a water treatment system
  • Value - Warranty, efficiency, longevity, operating cost and price
  • Support / Service - The company backing the system

Have Your Municipal Water Tested

Have your water tested by a reputable dealer or third party water testing lab, talk to your friends, neighbors, colleagues, check the Better Business Bureau and to search for a certified water treatment expert in your area, go to WQA.org (Water Quality Association).

A proper water analysis is the most important aspect of water treatment.

If you have a sales rep come to your home for a water analysis have them test the water directly from the well and through a Demo-Softener (they should all have a demo softener) to help determine the type of iron present or any other problems with the water.

Here is a general water analysis and how a home water softener is sized for this application.

Hardness = 20 grains per gallon
Iron =        1 part per million (4 gpg of hardness for every 1 ppm of iron)
PH =         7.4
TDS =       410 parts per million
H2S =       ND
----------------------
TCH 24 grains per gallon (total compensated hardness)
x 400 gallons used per day
= 9600 grains of total compensated hardness per day.

This equation would call for a 30,000 grain water softener and would regenerate every 2 days. (9600 grains of soft water are needed for reserve capacity.)

Conclusion: A home water softener alone may not always be the solution to every water treatment problem.

There are water problems such as high iron content, hydrogen sulfide, low PH, different types of iron and a myriad of other water related issues that may call for additional water treatment equipment to properly treat the water and provide your home and family quality water.

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