Water Filters Buying Guide: Pitcher, Faucet, Under-Sink, Whole House

Walk into any home goods store and you will find rows of water filters — pitchers, faucet attachments, under-sink systems, whole-house units — each claiming to remove different contaminants. Choosing the right filter can be confusing, but it does not need to be. This guide walks you through the types of water filters, what they remove, how to choose the right one, and how to maintain it.

Step 1: Know Your Water

Before choosing a filter, you need to know what is in your water. Start by requesting the Consumer Confidence Report (annual water quality report) from your water utility, which is required by law in the United States and lists the levels of regulated contaminants. If you have a private well, you will need to have your water tested by an EPA-certified laboratory — wells are not regulated and can contain contaminants that municipal water does not.

Common contaminants that may be present in tap water include chlorine and chloramine (disinfectants that affect taste and odor), lead (from old pipes and solder), arsenic (naturally occurring in some areas), nitrates (from agricultural runoff), pesticides, industrial chemicals (like PFAS), and pathogens (bacteria, viruses, parasites). The right filter depends on which of these are present in your water and at what levels.

For most people on municipal water in developed countries, the water is safe to drink, and filtering is a matter of improving taste and odor (removing chlorine) and providing additional protection against contaminants that may be present at low levels. If you have specific concerns — lead, arsenic, nitrates, PFAS — you need a filter certified to remove those specific contaminants. Generic "improves taste" filters may not address serious contaminants.

Types of Water Filters

Pitcher Filters

Pitcher filters (like Brita, PUR, ZeroWater) are the most popular and affordable option. They use activated carbon to remove chlorine, taste and odor compounds, and some contaminants like lead (in newer models). They cost 20 to 40 dollars for the pitcher, with replacement cartridges every 2 to 6 months at 5 to 15 dollars each. Pros: inexpensive, easy to use, no installation, portable. Cons: slow filtering, limited capacity, does not remove all contaminants, frequent cartridge changes.

Faucet-Mounted Filters

Faucet-mounted filters attach directly to your kitchen faucet and filter water on demand. They use activated carbon and sometimes additional media, removing chlorine, lead, and some other contaminants. They cost 25 to 60 dollars, with replacement cartridges every 2 to 3 months at 10 to 20 dollars each. Pros: easy installation, faster than pitchers, unlimited filtered water, can switch between filtered and unfiltered. Cons: may not fit all faucets, can slow water flow, limited contaminant removal.

Under-Sink Filters

Under-sink filters are installed beneath the kitchen sink and provide filtered water through a separate faucet. They range from simple carbon filters to multi-stage systems that can remove a wide range of contaminants. Prices range from 50 to 500 dollars, with replacement cartridges every 6 to 12 months at 20 to 100 dollars each. Pros: high capacity, hidden from view, can remove more contaminants, faster flow. Cons: requires installation (plumbing work), takes up under-sink space, higher upfront cost.

Reverse Osmosis Systems

Reverse osmosis (RO) systems are the most thorough home filtration option, removing virtually all contaminants including dissolved solids, lead, arsenic, nitrates, fluoride, and PFAS. They work by forcing water through a semi-permeable membrane. Prices range from 150 to 800 dollars, with annual maintenance costs of 50 to 150 dollars. Pros: removes almost everything, very pure water. Cons: wastes water (3 to 5 gallons per gallon filtered), removes beneficial minerals, requires installation, takes up significant under-sink space, slow production rate. For more detail, see our guide to reverse osmosis water.

Whole-House Filters

Whole-house (point-of-entry) filters treat all water entering the home. They are typically used for sediment removal, chlorine reduction, or water softening rather than for drinking water purification. Prices range from 200 to 2,000 dollars, with annual maintenance of 50 to 200 dollars. Pros: treats all water (good for showering, laundry, and appliance protection), single installation. Cons: expensive, does not provide drinking-water-level purification, requires professional installation, large footprint.

Countertop Filters

Countertop filters sit on the kitchen counter and connect to the faucet with a diverter valve. They offer more filtration capacity than pitchers or faucet filters but do not require under-sink installation. Prices range from 50 to 300 dollars. Pros: easy installation, more capacity than faucet filters, can include multiple stages. Cons: takes up counter space, may not fit all faucets, less powerful than under-sink systems.

Certifications to Look For

When choosing a water filter, look for certification from independent organizations that verify performance. The two most respected certifications are NSF International and the Water Quality Association (WQA). NSF certifies filters under various standards: NSF 42 (aesthetic effects like chlorine, taste, odor), NSF 53 (health effects like lead, cysts, VOCs), NSF 58 (reverse osmosis systems), NSF 401 (emerging contaminants like pharmaceuticals), and NSF 442 (PFAS). WQA uses the same standards under its Gold Seal program.

A filter certified to NSF 53 for lead removal, for example, has been independently tested and verified to remove lead to a specified level. A filter that claims to "reduce lead" without certification may or may not actually do so. Always check the certification, not just the marketing claims. The certification should specify which contaminants are removed and to what level.

Maintenance and Replacement

Filter cartridges must be replaced on schedule to maintain effectiveness. An old or saturated filter can become a breeding ground for bacteria and may stop removing contaminants effectively — in some cases, it can even release trapped contaminants back into the water. Follow the manufacturer's replacement schedule, which is typically based on time (every 2 to 6 months for pitchers, 6 to 12 months for under-sink systems) or volume (a certain number of gallons filtered).

Some filters have indicator lights or apps that remind you when to replace the cartridge. If yours does not, set a calendar reminder. Keep spare cartridges on hand so you can replace them immediately when needed. Store filtered water in a clean container in the refrigerator and use it within a few days — filtered water lacks the chlorine that protects tap water from bacterial growth.

For more on water quality topics, see our guides to water quality and filtration, reverse osmosis water, and hard water vs soft water. For general hydration, use our Daily Water Intake Calculator.