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Question DetailsAsked on 3/14/2015

which soft water system is best used with a tankless water system

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Because tankless water heaters (presumably what you meant) tend to be quite prone to both internal corrosion and blockage with lime and iron buildup and can really run amok with iron algae if not used frequently, the system that best removes the particulates / iron/ manganese/ lime and also does not add a lot of anything else to the system, like resin or salt.

So, with the realization that specific conditions and water chemistry would affect the result, in general I would say that setting aside cost issues the following order from best down probably (with chlorination or ozone treatment as necessary for each except #1) :

1) "best" would undoubtedly be a full distillation system, followed by

2) reverse osmosis, then probably

3) a three-stage saltless filtration, floculation, sandbed and carbon finishing system,

4) then a conventional resin based water softener, then

5) a a recirculating filtration media bed and salt based water softener, then

6) a simple filter cartridge system,

7) with a sand filtration and salt system probably being worst.

Of course, once you bring cost into it the picture changes for each specific case, commonly taking out at least #1 and #3 and in many cases #2 as well - but I would certainly recommend at a minimum a filtration cartridge to remove algae and silt and such if you have that in your water to prevent sedimentation and growth in the unit - preceded by treatment for whatever issues your water has. Chlorination can also help a lot with well water that has pipe algae growth issues.

Of course, if the tankless heater is only serving one consumption point like a kitchen sink then preceding it with an RO unit is a lot more practical than for a whole-house system.

Also, consider that the tankless unit is likely to have maybe a 3-5 year difference in life with better water treatment, so spending a LOT of money on better treatment might not be cost effective versus just more frequent heater replacement, especially if you are likely to do the every 3-6 year move to a new house that most Americans do. Also, bear in mind the fancier units also cost more to maintain, so you can end up chasing a moving target if you are not careful. I have seen cases where it was cheaper for a client to install a LARGE water storage tank with chlorinating and oxygenating recirculating pump and truck city treated water in every week or two than to treat the poor well water they had - isolating the toilets on a separate system from the well, and all other uses from the imported water.

Answered 4 years ago by LCD

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