When making the choice between a water softener system and a whole-house system, the main question to be answered first is: what is the quality of the incoming water? Most municipal and rural systems take ground water (wells) as the primary source water. This water tends to have higher percentages of dissolved minerals than surface water.
High mineral content is commonly referred to as hard water. Water softeners concentrate on removing minerals from water.
Whole house filtration systems address a broader spectrum of water quality issues.
The most common water softening systems are salt-based systems, which replace hard water minerals with salt ions. Also common are non-salt softening systems which do not add salts to the water but are vulnerable to even trace amounts of oil or hydrogen sulfate.
For small volume uses, magnetic systems will pull metallic minerals from water.
Softener Advantages and Disadvantages
Salt-based water softeners add sodium (and some potassium) to the water. They require regular maintenance, including restocking consumable salt, and are in the $1,000 to $3,000 range to install.
Non-salt systems require less maintenance and start around $1,500 but are damaged by trace amounts of oil. Magnetic systems have the least maintenance expense, can be installed for under $1,000 but have no effect on non-metallic dissolved materials.
Whole House Filtration
These are usually two-stage filtration systems. The first stage traps particles larger than 10 to 100 microns in size, and the second stage traps smaller particles.
This arrangement allows a much longer useful lifetime for the finer membrane (and more expensive) second stage filter. Unlike softening systems, filtration systems filter out all particles larger than the membrane rating of the second filter.
This means they remove metals, non-metals and biological particles such as bacteria. All filtration systems will require as much or more maintenance (back-washing, filter replacement, etc) as the most maintenance-intensive water softening systems.
The more effective systems have higher installation costs than the most expensive softening systems, as well.
The effectiveness of a filtration system is based on the smallest size particles it removes from water. The more particles removed, the higher the cost.
Cloth and Depth filters will remove particles larger than 10 micron (100,000 angstroms). This includes contaminants such as sand, pollen and larger Giardia.
Microfilters are rated from 10 micron down to 1/100 micron. Filters rated below 1/10 micron will remove bacteria as well as both Cryptosporidium and Giardia (two pathogens targeted by municipal treatment plants).
The finest microfilters will also remove most colloidal metals from water. The highest commonly available level of filtration is Reverse Osmosis (RO) filtration.
These systems are rated between 1/1,000 micron and 1/10,000 (1 angstrom). Although expensive ($10,000 and up) to install, RO systems remove viruses, dissolved organics and even metal ions from water.
Home water treatment systems are available to remove anything from metal particles through metal ions from incoming water. They may add salts or potassium into the system, which is a health concern, or they may remove beneficial metals and fluorides from the water along with pathogens.
In general, filtration systems are more expensive to install and maintain than softener systemsIf the need is simply to make the water less hard, softening systems will be more cost effective. However, if there are additional water quality concerns such as waterborne pathogens or bad taste, softening systems will not address those problems.