Residential reverse osmosis systems are large, expensive, wasteful, unnecessary and ineffective against certain types of contaminants.


The size may not be important to you, but even the compact version that some companies offer for "under-the-counter" purification requires adequate space for mounting and a drainage pipe for discharging wastewater.


For example, the least expensive under-the-counter system currently retails for around $350. The manufacturer added a granulated carbon step, so it removes chlorine. But, other than that, it only removes lead and cysts.


Depending on the unit you choose, you could need to call both a plumber and an electrician for installation. If you don't have a drain available for use, one will have to be installed. Any homeowner can install the kitchen countertop purifier that I mentioned with minimal effort. Why pay for all of this, when you don't have to?


The wastewater created by reverse osmosis systems residential designs is enough to frustrate most homeowners. Water bills go up, so that's another expense. If reverse osmosis system leaks, you've got a real mess on your hands. And, there's still one more disadvantage.


Residential reverse osmosis systems remove any naturally occurring mineral content that is present in your source. All surface and groundwater has some natural mineral content. With selective filtration, you remove all of the health hazards and everything that ruins the taste without destroying the mineral content.