A.J. Alberts Plumbing service van at a Twin Cities home, locally owned and operated since 1989

Under-Sink Water Filter Installation

An under-sink reverse osmosis system is the most effective way to get clean drinking water at your kitchen tap. It removes chlorine, dissolved metals, fluoride, and PFAS (with a certified membrane), fits in the sink cabinet, and feeds your refrigerator ice maker too. A.J. Alberts installs them across the Twin Cities with code-compliant drain connections and a lifetime craftsmanship warranty.

Call 651-738-0580

Quick Summary

A.J. Alberts installs under-sink water filters and reverse osmosis systems across the Twin Cities, typically in about 90 minutes, including the dedicated faucet, drain connection, and optional refrigerator line. PFAS-rated membranes available for East Metro homes. Free on-site water test first, written upfront pricing, installed by plumbers rather than commissioned salespeople. Call 651-738-0580.

Under-Sink Filter vs Under-Sink Reverse Osmosis

Both live in the sink cabinet, but they are very different machines. Here is the honest comparison for Twin Cities water.

Simple Carbon Filter

One or two cartridges inline on the cold supply. Improves taste and removes chlorine.

What it does NOT remove:

• Dissolved metals (lead, copper)
• Fluoride and nitrate
• Sodium added by your softener
• Most PFAS at meaningful reduction rates

Reverse Osmosis (what we recommend)

Multi-stage system with a membrane that removes nearly all dissolved contaminants, plus a storage tank and dedicated faucet.

What you get:

• Chlorine, metals, fluoride, nitrate removed
• PFAS removal with NSF/ANSI 53 or 58 certified configuration
• Sodium from softening removed
• Filtered refrigerator ice and water (optional line)

What a Professional Install Includes

The two places under-sink installs go wrong are the drain connection and the faucet penetration. Both are permanent plumbing work, and both are inside a cabinet where a slow leak can go unnoticed for months.

Feed valve on the cold supply

A proper tee with its own shutoff, so the system can be serviced without shutting down the sink.

Dedicated faucet

Mounted through the countertop, sink deck, or an existing sprayer hole. Drilling granite or quartz takes the right bit and experience, and this is the step that stops most DIY installs.

Code-compliant drain connection

RO membranes flush reject water to the drain. The saddle connection must be placed correctly relative to the trap, which is exactly the kind of detail a plumber gets right and a kit instruction sheet does not explain.

Optional refrigerator line

Filtered ice and door water from the same system. Run cleanly through the cabinets, not stapled across the back wall.

Pressure test and lifetime craftsmanship warranty

Every joint checked under pressure before we leave, and the workmanship is covered for life.

Why Twin Cities Water Changes the Spec

Hard water kills membranes. Metro water runs 13 to 22 grains per gallon. An RO membrane fed unsoftened water of that hardness scales early and fails years ahead of schedule. If you have a softener, your membrane lives long. If you do not, we will tell you honestly whether to add one or simply budget more frequent membrane changes.

PFAS is a real factor in the East Metro. For homes in Woodbury, Cottage Grove, Lake Elmo, Oakdale, and the surrounding documented contamination zone, we configure the system with PFAS-rated membranes and pre-filters certified to NSF/ANSI 53 or 58, and we usually pair under-sink RO with whole-home carbon filtration for layered protection.

Softened water tastes salty to some people. Ion-exchange softening adds sodium. RO removes it at the drinking tap, which is why the softener-plus-RO combination is the standard configuration we install: soft water for the house, clean low-sodium water for drinking and cooking.

Under-Sink Filter Installation FAQs

How do you install an under-sink water filter?

A professional under-sink RO install takes about 90 minutes: shut off the cold supply, tee in a feed valve, mount the filter manifold and storage tank in the cabinet, drill the countertop or sink deck for the dedicated faucet (or reuse a sprayer hole), connect the drain saddle for membrane flush water, then pressurize and check every joint. The drain connection and the faucet hole are where DIY installs most often go wrong, and both can mean water damage inside the cabinet. We install them to plumbing code with a lifetime craftsmanship warranty.

What is the difference between an under-sink filter and under-sink reverse osmosis?

A simple under-sink filter (usually a single carbon cartridge) improves taste and removes chlorine, but it does not touch dissolved metals, fluoride, nitrate, sodium, or most PFAS. Under-sink reverse osmosis pushes water through a membrane that removes nearly all dissolved contaminants. In the Twin Cities, where PFAS and hard-water sodium are real considerations, RO is the configuration we recommend for drinking water at the kitchen tap.

Does an under-sink RO system work with my refrigerator ice maker?

Yes. We routinely run a line from the RO system to the refrigerator so ice and door water are filtered too. It needs adequate tubing length and sometimes a small pressure consideration, both of which we handle during install.

How much does under-sink RO installation cost in the Twin Cities?

It varies with stage count (3, 4, or 5 stage), whether the membrane is PFAS-rated, and whether we add a refrigerator line. A.J. Alberts provides written upfront pricing after a free in-home water test, and our pricing on water treatment equipment consistently comes in below the specialty water-conditioning brands. No commissioned salespeople.

How often do under-sink filters need to be changed?

Pre-filters (sediment and carbon) every 6 to 12 months, the RO membrane every 2 to 5 years. If your home has a water softener ahead of the RO unit, the membrane lasts dramatically longer because hardness is what scales membranes. We offer filter change service or set you up to do it yourself in five minutes.

Do I need a plumber to install an under-sink water filter, or can I DIY it?

Simple single-cartridge filters are a reasonable DIY for a handy homeowner. RO systems involve a drain saddle connection, a new faucet penetration, and a pressurized storage tank, and a slow leak inside a sink cabinet can quietly destroy the cabinet floor. If you DIY it, check it weekly for the first month. If you want it done once with a craftsmanship warranty behind it, that is what we do.

Sources & Citations

Clean Water at Your Kitchen Tap

Free in-home water test first. Then a written quote for the right under-sink system, installed by a plumber and warrantied for life.

Schedule Free Water Test Call 651-738-0580