You may not need to be Sherlock Holmes to solve this particular riddle, but it’s worth spelling out exactly what a point-of-entry filter system is.
Instead of filtering water as it reaches/pours from the tap, POE filters are integrated into your home’s connection at the earliest point on the mains water pipe—normally after a pressure tank, if there is one. Whole house filtration systems are almost always multi-stage affairs, consisting of water softeners, UV purifiers, reverse osmosis membranes, and carbon filters, in various combinations.
Exactly what components a whole-home filter uses will depend on the water source. For properties on well water, a filter will usually include a mechanical sediment filter, followed by a water softener, followed by an ultraviolet system to kill pathogens. Those on pretreated city water supply may use fewer stages, targeted at sediments, chlorine, or chloramine.
But whatever the design, whole house filters are going to treat all the water entering a home, from your shower to your washing machine.
How do POE filters differ from POU filters?
Aside from their comprehensive coverage, the biggest difference between POE filters and traditional point-of-use filters (think: Brita filter) is filtering power. With the exception of pricey revere osmosis under-sink models—and visually appealing but equally expensive ceramic filters—almost all POU filters rely on activated carbon to treat water.
When chemically treated and ground-down, carbon develops small pockets on its surface, giving it a huge bump in surface area. So much, that a single gram of activated charcoal can have a surface area of over 2000 meters squared.
Ramping up the surface area increases carbon’s adsorptive property—its ability to attract and bind organic compounds to its surface. When water runs through the filter, solutes such as chlorine, which are responsible for bad-tastes and smells, should stick to the carbon.
However, this kind of basic carbon filtering seen in most POE systems is ineffective against non-organic materials or micro-organisms, making most pitchers, countertop, and under-sink filter models only suitable for taste corrections. Most whole house filters will also make use of activated carbon, but usually as part of a multi-stage filtering process that’s designed to do a lot more than improve water taste.
How much do whole-home filters cost?
Base prices for whole house filters depend almost entirely on the particular combination of filtering stages required. On top of the base price, you’ll also need to build in between $75 and $150 per year or so for replacement cartridges, plus the cost of electricity for any powered elements, such as a UV lamp. And, don’t forget the price of labor, should you not feel confident in messing with your plumbing.
A three-stage carbon/zinc POE filter (one stage for sediment and rust, a second for metals, and a third for organic compounds) retails for anywhere between $200-$750. Most whole-house systems used in hard water areas also take the opportunity to install a water softener, which can add approximately $500 or so.
Combine a carbon filter and softener with reverse osmosis (RO) system—which applies pressure to drive water through super-fine membranes and catch contaminants of less than 0.001 microns—and you’ll be in the low thousands.
Finally, add an ultraviolet filter to the mix, as a way of ensuring any remaining viruses or the tiniest of microorganisms and rendered inactive, and you might be looking at a system worth upwards of $5000.
Why should you invest in a POE filter?