An under-sink filter treats the water for a single tap, such as the kitchen sink. pHountain Water Filtration sells the 3-Stage Water System in Nassau and Suffolk, with professional installation. Here is how under-sink filters compare with reverse osmosis and whole-home systems, with every fact linked to its source.
Sold by Phone
pHountain Water Filtration sells the 3-Stage Water System by phone in Nassau and Suffolk, professionally installed in homes on public water or a private well. It sits under the kitchen sink. Call for its specifications, price and installation details.
Under-sink filter with three filter stages
A three-stage filter that sits under the kitchen sink and supplies filtered water for drinking and cooking.
Replacement parts in our online store: 3-Stage Filter Replacements Set.
An under-sink filter is a point-of-use system. The CDC says “Point-of-use systems treat water in batches and deliver it to a single tap, such as your kitchen sink,”[1] and EPA notes that “Under the sink systems are another POU option.”[2]
A whole-home system works differently: “Whole-home or point-of-entry systems treat most or all of the water that enters your home.”[1] pHountain Water Filtration’s main service is whole-home filtration, professionally installed at the main water line.
General information. This section describes a filter technology EPA covers, not any particular system. What a specific filter reduces is shown on its label and by its certification for each contaminant.
EPA describes granular activated carbon (GAC), one of the materials used in point-of-use filters: “Granular activated carbon in a filter traps chemicals as water passes through the material. GAC materials are extremely porous, and the small pores trap the contaminants present in the water.”[2]
EPA also notes that “Filters have a limited capacity, requiring periodic replacement.”[2]
Reverse osmosis is also installed under the sink, but it works differently. EPA explains that “RO is the process by which pressure forces water through a semi-permeable membrane, creating a stream of treated water, called ‘permeate,’ and a stream of reject water called ‘concentrate’ or ‘brine.’”[3] That untreated water “is sent ‘down the drain’ to septic or municipal sewer systems.”[2]
Reverse osmosis can also lower minerals: the CDC lists calcium, magnesium and potassium among the substances it may reduce.[1] Our reverse osmosis page covers it in more detail.
The CDC advises: “Check your treatment system’s label to make sure the system removes the chemicals or germs you are concerned about.”[1] For PFAS, EPA says to “Look on product labels for certification under NSF/ANSI 53 or NSF/ANSI 58 for PFAS reduction.”[2] For any specific contaminant, ask for independent certification data (for example NSF/ANSI listings) for the exact system you are considering.
Upkeep matters too: “Filters are only effective if they are maintained according to the manufacturer’s instructions for how long their filters or membranes will last before they need to be replaced.”[2] The 3-Stage Filter Replacements Set for the 3-Stage Water System is sold in our online store; ask us for its replacement schedule.
An under-sink filter treats the water for one tap. pHountain Water Filtration’s main service, whole-home filtration, treats the water at the main line.
| System | What it is | Where it goes | More |
|---|---|---|---|
| pHountain Filtration System (whole-home) | Whole-home (point-of-entry) system | At the main water line | Details |
| 3-Stage Water System | Under-sink filter with three filter stages | Under the kitchen sink | On this page |
| Lifeguard Reverse Osmosis System | Under-sink reverse osmosis system | Under the kitchen sink | Details |
| Lifeguard Alkaline Reverse Osmosis System | Under-sink reverse osmosis with an alkaline remineralization stage | Under the kitchen sink | Details |
| Aerus Elevate pH Max System | Water ionizer | On the countertop or under the sink | Details |
| Mineralizer System | Mineral stage for filtered drinking water | Added to a compatible filtration system | Details |
Free In-Home Water Test
pHountain Water Filtration offers a free, no-obligation in-home water test. A local specialist tests your water at your home and explains the results, and our specialists are trained for both well water and municipal supply.
The CDC notes: “If your tap water does not contain harmful chemicals or germs, you may not need a home water treatment system.”[1]
On public water, the Safe Drinking Water Act has EPA set “national health-based standards for drinking water,” and “US EPA, states, and water systems then work together to make sure that these standards are met.”[4] Your supplier’s annual water quality report shows what was found: “Reports must be sent by your water supplier each year by July 1.”[5] Private wells are different: “SDWA does not regulate private wells which serve fewer than 25 individuals.”[4] Our private well guide explains testing.
Measuring PFAS and 1,4-dioxane at the levels regulators use (parts per trillion and parts per billion) requires analysis by a certified laboratory; a free in-home water test is a starting point for understanding your water and your options.
Tell us about your home and we will reach out to schedule your free water test.
FAQ
A filter installed under the kitchen sink that treats the water for that tap. The CDC calls these point-of-use systems: they treat water in batches and deliver it to a single tap, such as the kitchen sink. EPA lists under-the-sink systems as one point-of-use option.
A whole-home, or point-of-entry, system treats most or all of the water that enters the home, as the CDC describes it, while an under-sink filter treats the water for a single tap. pHountain Water Filtration's main service is whole-home filtration, professionally installed at the main water line.
Reverse osmosis uses pressure to push water through a semi-permeable membrane and sends a stream of reject water down the drain, as EPA describes it. The CDC lists calcium, magnesium and potassium among the substances reverse osmosis may reduce.
The CDC advises checking a treatment system's label to make sure it removes the chemicals or germs you are concerned about. For PFAS, EPA says to look on product labels for certification under NSF/ANSI 53 or NSF/ANSI 58. For any specific contaminant, ask for independent certification data (for example NSF/ANSI listings) for the exact system you are considering.
EPA notes that filters have a limited capacity and need periodic replacement, and that they are only effective if they are maintained according to the manufacturer's instructions. Ask us for the 3-Stage Water System's replacement schedule; its replacement filter set is sold in our online store.
Under the Safe Drinking Water Act, EPA sets national health-based standards for drinking water, and EPA, states and water systems work together to make sure those standards are met. Your supplier's annual water quality report shows what was found in your water; EPA says it must be sent each year by July 1. The CDC notes that if your tap water does not contain harmful chemicals or germs, you may not need a home water treatment system. The law does not regulate private wells that serve fewer than 25 people.
Call pHountain Water Filtration at 1-631-991-3995, Monday to Friday 9 a.m. to 5 p.m. or Saturday 10 a.m. to 2 p.m., for price and installation details. We sell it in Nassau and Suffolk Counties, professionally installed in homes on public water or a private well. Financing is available for eligible customers. Its replacement filter set is sold in our online store.
Sources checked .
This page was prepared by pHountain Water Filtration in Islip, NY. Its general water facts are quoted from the public sources listed above; the system descriptions and sales details are pHountain Water Filtration’s own.
Call to Ask
Call 1-631-991-3995 (Mon–Fri 9 a.m.–5 p.m., Sat 10 a.m.–2 p.m.) for price and installation details, or book a free in-home water test.