How to decide whether or not you need a twin tank softener

Twin Tank Water Softeners certainly have their place, and if money was no object I may even have one in my home. Unfortunately, money is an object for me. I also understand that, all too often, Twin Tank water softeners are oversold as a necessity.

For the majority of consumers, a properly sized single tank water softener will regenerate within 7-14 days providing more than enough soft water availability. Adding hundreds, and sometimes thousands of dollars to your purchase to avoid having hard water at 2am for a brief period once every week or two, is not my idea of good value.

Because there are times when Twin Tank softeners are a good idea, here is some brief information to help paint the picture.
To decide whether or not I need a twin tank softener, 3 factors are considered:

  • Water Quality
  • Water Consumption (Gallons Per Day)
  • Application (Household, Business, Factory, Restaurant)

Water Quality & Consumption

Water Quality has a direct correlation of how many gallons of water can be softened before “running out of soft water” and needing to regenerate. Water quality should be measured in Total Compensated Hardness which will include Hardness and Iron.

Water consumption simply refers to how much water you go through in a day.

Water Consumption and Water Quality will determine the size or configuration of the water softener.


A standard family household on city water will be ok with having hard water once a week from 2am-3:30am. A 24/7 processing plant that requires soft water will not be ok with hard water at any time.

*Let’s look a couple scenarios.

Scenario A)

  • 5 People in a household with North St. Paul, MN City Water (15 grains of hardness)
  • 5 People x 60 Gallons Per Person = 300 Gallons Per Day
  • 300 Gallons x 15 Grains of Hardness = 4, 500 Grains Per Day
  • A standard one cubic foot water softener will typically remove 28, 000 grains
  • 28, 000 / 4, 500 = 6.22 days between regenerations.

In Scenario A the properly sized water softener will regenerate approximately every 6 days which is a good fit for this household.

Scenario B)

  • 5 People in a household with a private well in Ham Lake, MN (25 grains of hardness, 5 Parts of Iron)
  • 5 People x 60 Gallons Per Person = 300 Gallons Per Day
  • 50 Grains Hardness (Hardness and Iron) x 300 Gallons Per Day = 15, 000 Grains Per Day
  • To have 4 days between regenerations the softener would have to remove 60, 000 grains which would be a very large water softener

In Scenario B a twin tank softener is ideal because it can regenerate mid-day and continue to provide soft water. It will also regenerate with soft water which is an added benefit due to the amount of iron in the water. Ideally, an iron filter should be used to remove the iron first and allow the softener only to handle hard water making it much more effective and efficient.

*You should always consult a water professional to perform a water analysis and recommend a proper system.


There are benefits to twin tank water softeners for those who are in the market or have a need for a twin tank softener.

  • 24 Hour a Day Soft Water – You’ll have soft water even during the weekly regeneration at 2am.
  • More Efficient – When a regeneration is triggered on a single tank system it will regenerate that night even if there is 50 gallons still available. A Twin tank softener will meter down to zero capacity.
  • Soft Water Regeneration – For iron free water supplies soft water regeneration is an oversold benefit, but is a great feature for moderate to high amount of iron.

Working with a company with over 53 years of experience such as Merles Water Conditioning will guarantee you a professional recommendation without a sales agenda.

Would you like more information or are you ready to make a purchase?