Water Filter Systems
Water filter systems reduce sediment, chlorine, and other contaminants in a building's water supply. Point-of-use units install at a single sink to treat drinking and cooking water, while point-of-entry units install on the main line to treat water for every fixture. Selection depends on water source, flow demand, and the contaminants to be reduced.
The range covers under-sink, reverse osmosis, whole house, cartridge housing, commercial, and countertop units for residential water filtration systems and light commercial work. Each group below explains where the system installs, what it connects to, what it treats, and how it is serviced. Specifications and selection guidance follow the product groups. Replacement cartridges, housings, wrenches, and mounting hardware are listed under Water Filter Accessories.
Water Filter Systems Products
Under-Sink Water Filtration Systems
Under-sink water filtration systems connect to the cold supply line below the sink, usually through a tee adapter at the angle stop. Treated water feeds a dedicated faucet from Kitchen & Bar Faucets or the existing faucet, depending on the model. Most use carbon block or multi-stage cartridges.
Reverse Osmosis Systems
A reverse osmosis water filtration system passes water through sediment and carbon pre-filters, then a semipermeable membrane that reduces dissolved solids. Tank-style units include a pressurized storage tank, a dedicated faucet, and a drain line that channels reject water to the sink drain.
Whole House Filtration Systems
Whole house water filtration systems install on the main water line after the shutoff valve and ahead of the water heater, so treated water reaches every fixture and appliance. They use cartridge housings or media tanks sized by flow rate and pipe diameter.
Inline and Cartridge Housing Systems
Inline systems use standard housings that thread onto the supply line. Common cartridge sizes are 10 or 20 in. long and 2.5 or 4.5 in. in diameter. Housings mount in series to combine sediment and carbon stages, with ports from 1/2 to 1 in. Clear sumps allow visual checks of sediment loading.
Commercial and Foodservice Filtration
Commercial water filtration systems treat water for ice machines, coffee brewers, beverage dispensers, and steam equipment. Many foodservice filters combine carbon with a scale inhibitor to limit mineral buildup. Systems are sized by equipment flow rate and gallons treated between cartridge changes.
Countertop and Faucet-Mount Filters
Countertop units connect to the faucet through a diverter or operate by gravity, while faucet-mount filters attach in place of the aerator. Neither requires cutting into supply lines, which suits rental units and temporary setups. Cartridge capacity is lower than plumbed systems, so replacement intervals are shorter.
How Water Filter Systems Work and Where to Use Them
Filtration Stages and Media
Sediment filters capture sand, rust, and scale particles. Activated carbon reduces chlorine, taste, odor, and many organic chemicals. RO membranes reduce dissolved solids, and UV units disinfect without removing particles. Multi-stage systems place sediment ahead of carbon to protect downstream media and extend cartridge life.
Point-of-Entry and Point-of-Use Placement
Point-of-entry systems treat all water entering the building, including water for showers, laundry, and water heaters. A point of use water filter treats water at one tap, using smaller cartridges where water is consumed. Many installs pair both: a whole house sediment and carbon stage with an RO unit at the kitchen sink.
Residential and Commercial Applications
Residential installs cover kitchen sinks, bar sinks, refrigerator lines, and whole house treatment. In restaurants, offices, and facilities, water filtration equipment protects ice makers, beverage equipment, and drinking fountains.
Key Specifications and Planning Steps
Flow Rate and Line Size
Water filter systems are rated by flow in gallons per minute (GPM). Match that rating to the peak demand of the fixtures served, and use ports that match or exceed the supply line diameter to limit pressure loss.
Certification
Check for NSF/ANSI 42 (chlorine, taste, and odor), NSF/ANSI 53 (health-related contaminants such as lead), NSF/ANSI 58 (reverse osmosis), or NSF/ANSI 401 (emerging contaminants). Listings cover specific contaminants, so confirm the target is included. Verify listings in the certifier's online database.
Service Access
Leave clearance below housings for cartridge removal. Isolation valves on both sides, plus a bypass on whole house systems, keep water on during service. Where a metal pipe is part of the electrical grounding path, a bonding jumper across the filter maintains continuity.
Choosing the Right Water Filter System
The right water filtration solution starts with a water test or the utility's annual water quality report. Carbon handles chlorine taste and odor on municipal water. Well water often needs sediment pre-filtration, and bacteria or iron call for UV or dedicated media. Filters do not remove hardness minerals, so hard water needs a softener or scale-control conditioner.
Next, count the fixtures served. For commercial kitchens, size each unit to the equipment it feeds. A single drinking tap suits a drinking water filtration system under the sink, while building-wide concerns call for point-of-entry treatment. For a water filter system for home, check cabinet space, drain access for RO, and an open faucet hole. Complete the connection with matching supply lines and pipe fittings rated for potable water.
Frequently Asked Questions
Where can I buy water filter systems for a residential plumbing job, including under-sink and whole house units?
The water filter systems in this category cover residential jobs in under-sink, reverse osmosis, whole house, inline housing, and countertop formats. Choose by installation point, rated flow, and the contaminants listed on the system's NSF/ANSI certification.
What commercial water filtration systems should I spec for a restaurant or coffee shop kitchen?
Spec point-of-use commercial water filtration systems for each piece of equipment, such as ice machines, coffee and espresso brewers, and beverage dispensers. Most combine sediment and carbon stages with a scale inhibitor. Size each unit to the equipment's flow rate and water use, and follow the equipment manufacturer's water quality requirements.
What's the difference between a whole house water filtration system and an under sink water filtration system?
A whole house water filtration system installs on the main line and treats all water entering the building, including water for showers and appliances. An under sink water filtration system installs on the cold line at one sink and treats only the drinking and cooking water from that tap.
Is a reverse osmosis water filtration system better than a carbon filter for drinking water?
Carbon reduces chlorine, taste, odor, and many organic chemicals. A reverse osmosis water filtration system adds a semipermeable membrane that also reduces dissolved solids such as nitrate, fluoride, and many metals. RO produces water more slowly and sends rejected water to the drain, so the choice depends on which contaminants need reduction.
Should I install a point of use water filter or a point of entry system for a home with city water?
City water is usually treated with chlorine or chloramine. If the concern is taste or a specific contaminant at the drinking tap, a point of use water filter covers it. If the concern is chlorine at showers and appliances, choose point-of-entry treatment. Chloramine requires catalytic carbon media.
What size water filter system do I need to keep flow rate up for a whole house?
Size the system by flow rate. Its GPM rating should meet the home's peak demand, based on how many fixtures and bathrooms run at once. Ports should match the main line, commonly 3/4 or 1 in. Housings with a 4.5 in. diameter pass more flow with less pressure drop than 2.5 in. housings.
Where should a whole house water filter be installed on the main water line, before or after the water heater?
Install it after the main shutoff valve and before the water heater, so both hot and cold lines receive filtered water. On well systems, it goes after the pressure tank. Hose bibs used for irrigation can stay upstream of the filter to save cartridge capacity.
Does an under-sink reverse osmosis system need a separate faucet and a drain connection?
Most tank-style under-sink RO units need both. The dedicated faucet mounts in a sink or countertop hole, and a drain saddle on the sink tailpiece above the P-trap carries reject water. Some jurisdictions require an air-gap faucet, so check local code.
What NSF/ANSI certification should a drinking water filtration system have?
A drinking water filtration system should be certified by an ANSI-accredited body such as NSF or WQA. NSF/ANSI 42 covers chlorine, taste, and odor. NSF/ANSI 53 covers health-related contaminants such as lead. NSF/ANSI 58 covers reverse osmosis systems, and NSF/ANSI 401 covers emerging contaminants. Confirm that the listing names the specific contaminant.
How do I change a whole house filter cartridge without shutting off water to the building?
Install a bypass valve or a three-valve bypass loop. Close the inlet and outlet isolation valves, open the bypass, and relieve pressure before removing the sump. Water continues to the building unfiltered until the filter is back in service.
How often do the filters in a residential water filtration system need to be replaced?
Follow the manufacturer's rated capacity in gallons or months, whichever comes first. Sediment cartridges in residential water filtration systems load faster on water with high sediment, which shows as a pressure drop across the housing. RO pre-filters are changed more often than the membrane.
What parts do I need to install an under sink water filtration system besides the filter unit?
Most under sink water filtration systems need a cold water adapter or tee at the angle stop, tubing, and mounting screws. RO units also need a drain saddle and a faucet hole. Check the kit contents, then add supply lines or fittings as needed.
Can one water filter system for home handle both well water and sediment problems?
One water filter system for home can combine a sediment pre-filter with carbon for well water. Bacteria, iron, manganese, and hardness each need specific treatment, such as UV, oxidizing media, or a softener. Test the well water first so the treatment matches the results.
What water filtration equipment is used for ice machines and beverage dispensers?
Ice machines and beverage dispensers use point-of-use water filtration equipment that combines sediment filtration, carbon for chlorine taste and odor, and a scale inhibitor such as polyphosphate. Size the cartridge to the equipment's flow rate and daily water use.
How do I choose the right water filtration solution for hard water versus chlorine taste?
Chlorine taste responds to activated carbon, so a carbon-based water filtration solution handles it. Hardness minerals pass through standard filters. Reducing them requires an ion-exchange softener, while a scale-control conditioner limits scale without removing the minerals. Where both issues exist, combine the two systems.