Whole House Reverse Osmosis System, Who Really Needs One?

Since reverse osmosis technology was patented in the late 60′s and early 70′s by Minnesota based Osmonics and San Diego based Water Factory Systems, under sink ultrapure water systems are being used by millions of Americans and the consideration for whole house reverse osmosis systems is growing. The environmental impact of reverse osmosis systems may outweigh the benefits and should be considered by people interested in the technology.

Two types of water are produced from the reverse osmosis process of forcing water through a membrane, the “permeate” water, which is the water we consume and the “concentrate” which is the wastewater produced during the process. The “permeate” water by scientific definition is ultrapure water but it is low in total dissolved solids (TDS), has a low pH and is extremely corrosive. The “permeate” water while free of metals after the membrane such as iron, sodium, manganese, chloride and calcium, results in a 98% reduction in the solid levels when configured properly. The membrane discharges the “permeate” or treated water into a holding tank that is low pressure and the water level is controlled by either a float or level switch. The treated water is then delivered to the plumbing lines of the house by a secondary repressure pump (not part of the RO equipment). The repressure pump and the RO treatment pump both demand high amperage and voltage giving the reverse osmosis system the highest usage of kilowatt power in the market of whole house water treatment.

The high electrical usage is further increased by the need for a full pretreatment system needing to be installed ahead of an RO membrane, often involving a water softener, iron filter, carbon filter or in most cases all of them. The environmental issues and the need to own a full treatment system as a pretreatment leads responsible professionals to soft sell RO’s. RO membranes are costly to replace and are easily damaged or scaled up if the pretreatment system is absent or fouled. Anyone who has owned a water softener knows this is not an occasional occurrence.

There is a focus on three issues that have put reverse osmosis systems under intense scrutiny in the US by both environmental organizations and state regulators: 1. The energy use of reverse osmosis systems being so high. 2. The high (25-75%) waste of water. 3. The salinity and chloride discharge from both the salt based pretreatment system and the RO concentrate water.

Another Twin Cities Minnesota manufacturer claims a non-salt pretreatment system for both whole house and commercial RO applications and has been installing them as a package since 1995. “Since the mid 1990′s we have eliminated both the water softener and the iron filter in reverse osmosis applications. We have done so with a longer membrane life, fewer scaling issues at the membrane and a less corrosive final water,” said Larry Couture, Chief Technology Officer for the Twin Cities manufacturer.

The chemical free technology eliminates the need for salt softening by basically converting the calcium to a bicarbonate or soluble form. The system filters the iron and manganese regardless of the pH of the source water and no there is no sodium for calcium ion exchange to occur. The need for an RO system is completely eliminated in most case by their system, states Couture. If the chloride or sodium levels exceed 1,700 ppm would be the only time he would recommend the use of a reverse osmosis system. Usually coastal or brine intruded from the ocean or natural gas and oil exploration, these waters are rare.

Couture explained that he has recommended under sink reverse osmosis on rare occasions with their proprietary zero salt whole house systems, usually when treating lake water but their primary purpose has been to remove sodium from a water softener.

For those who require a whole house reverse osmosis system with high chloride levels in their source water it is essential to: 1. Buy an reverse osmosis system that is 95% or higher. 2. Buy equipment that produces at least three gallons of “permeate” usable water for every gallon of “concentrate” or waster water, 75% efficient equipment and upwards. 3. Purchase a non-salt pretreatment system. 4. Examine all equipment monthly and change out membranes annually. 5. Purchase a back up, second set of membranes or otherwise a complete second system.

Couture tells people “We can always add a reverse osmosis system later but if you’re on the edge of horrible source water we recommend you try our non chemical, non salt pretreatment system as a stand alone system for a month or two, living with the water first.

Learn more about ECOsmarte’s chemical free water, when Whole House Reverse Osmosis water systems make sense and how to avoid salt and operating costs after install.


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