The 6 Best Water Filters of 2026 (Read Your Water Report First)

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Our quick picks

Ranked by what each one is best at, not by a score we made up. Ratings are what the product showed on Amazon when we last checked — how we rank.

What follows is the reasoning, the specifications that change the decision, and the drawbacks.

Almost everybody shops for a water filter in the wrong order. They pick a product, then wonder what it removes. The useful order is the reverse: find out what is actually in your water, then buy the filter certified to remove it.

This is easier than it sounds and it costs nothing. If you are on a municipal supply in the US, your utility is required to publish an annual water quality report — often called a Consumer Confidence Report — listing what it tested for and what it found. It is usually on the utility’s website or available on request. Read it once and you will know whether your concern is chlorine taste, hardness, lead from your own plumbing, or something else entirely. If you are on a private well, nobody is testing it for you, and a laboratory test is necessary rather than optional.

The reason this matters is that filters are specific. A carbon pitcher that transforms the taste of chlorinated tap water may do nothing at all about nitrate. A reverse osmosis system that removes almost everything also removes minerals and wastes water doing it. And a filter certified for lead only removes lead while it is within its rated capacity — run it past that and you have a false sense of security rather than a filter.

Below are six filters across the four approaches that make sense for a home: under-sink reverse osmosis, under-sink carbon block, countertop RO for renters, and the cheap point-of-use options. First, though, the certification section, because the difference between “tested to NSF standards” and “NSF certified” is the difference between a claim and a verified fact. For the rest of the kitchen, see our guides to the best electric kettles and the best countertop ice makers.

Quick picks

• Best overall: Waterdrop G3P600 tankless reverse osmosis — high output, no storage tank under the sink, and genuine third-party certification.
• Best value reverse osmosis: iSpring RCC7AK-BN — NSF certified six-stage system with a remineralisation stage that puts minerals back after the membrane strips them out.
• Best for renters: Bluevua RO100ROPOT countertop RO — full reverse osmosis with no plumbing, no drilling and nothing to undo when you move.
• Best under-sink filter without reverse osmosis: Frizzlife under-sink system — NSF/ANSI 42, 53 and 401 certified, keeps the minerals, wastes no water.
• Best pitcher for a family: Brita XL 27-cup dispenser — enough capacity that you are not refilling it hourly, with the higher-performance BritaPlus filter.
• Cheapest way to reduce lead: PUR Plus faucet mount — screws onto the tap in two minutes and is certified for lead reduction.

Read this first: what a filter can and cannot do

This section comes before the recommendations because drinking water is a health matter and the marketing in this category is unusually loose. Nothing here is medical advice, and if you have a specific concern about your water — a child with elevated blood lead, a well near agricultural land, an unexplained illness — that is a conversation for your doctor and your local health department, not a product guide.

A filter does not make unsafe water safe

This is the most important limitation and the one most often glossed over. Ordinary home filters — pitchers, faucet mounts, carbon blocks, even most reverse osmosis systems — are designed for water that is already microbiologically safe and improve its chemistry and taste. They are not designed to make contaminated water drinkable.

• During a boil water notice, follow the notice. A carbon filter is not a substitute, and pouring unsafe water through a pitcher does not make it safe. Boil as instructed by your utility.
• After flooding, or if a well may be contaminated, do not rely on a domestic filter. Get the water tested and follow public health guidance.
• Only systems specifically certified for microbiological reduction — against standards covering bacteria, viruses or cysts — make any claim in that area, and the claim is narrow. Most home filters make none.
• Softeners are not filters. A water softener exchanges hardness minerals for sodium. It helps your kettle, your shower and your appliances; it does not remove lead, nitrate or most chemicals, and it adds a small amount of sodium.

Decode the certifications, because the wording matters

The meaningful standards are NSF/ANSI standards, and the crucial distinction is between a product certified to one and a product “tested to” or “designed to meet” one. Certification means an accredited third party — NSF International, the Water Quality Association, or IAPMO, among others — verified the claim and audits the manufacturer. “Tested to” often means the manufacturer sent a sample to a laboratory once.

• NSF/ANSI 42 — aesthetic effects. Chlorine taste and odor, particulates. This is the basic standard almost every carbon filter meets, and it is about how water tastes rather than health.
• NSF/ANSI 53 — health effects. This is the one that matters for lead, cysts such as cryptosporidium and giardia, VOCs, and certain other contaminants. Crucially, certification under 53 is contaminant-specific: a filter certified under 53 for chlorine reduction is not therefore certified for lead. Look for the named contaminant.
• NSF/ANSI 401 — emerging contaminants. Pharmaceutical residues, pesticides, and similar trace compounds.
• NSF/ANSI 58 — reverse osmosis systems. Covers total dissolved solids reduction and, depending on the certification, specific contaminants.
• NSF/ANSI 55, 244 and 419 deal with ultraviolet treatment and microbiological reduction. If pathogens are your concern, these are the standards to look for — and you should be working from a laboratory test, not a product page.

For any filter you are considering, the useful question is: certified by whom, under which standard, for which specific contaminants? Reputable manufacturers publish a performance data sheet answering exactly that. If you cannot find one, treat the marketing claims as unverified.

PFAS, lead, and the two contaminants people most often ask about

Lead generally does not come from the treatment plant — it comes from lead service lines, lead solder, or brass fixtures in your own building, which is why your utility’s report can look clean while your tap is not. If you live in older housing, this is worth taking seriously. A filter certified under NSF/ANSI 53 specifically for lead reduction, or a reverse osmosis system certified for lead, is the point-of-use answer, and it only works within the filter’s rated capacity. Running cold water for a while before drinking also helps, because lead leaches most while water sits still in the pipe. Never use hot tap water for drinking or cooking, as it leaches more.

PFAS — the family of persistent fluorinated compounds — are reduced effectively by reverse osmosis and by certain high-quality activated carbon blocks, and poorly or not at all by many basic pitcher filters. If PFAS is your concern, look for explicit certification against them rather than general assurances, and be aware that this is an area where regulation and testing have moved quickly, so check for current data rather than older claims.

An overdue filter can be worse than no filter

This is the maintenance point that matters most. A carbon filter works by adsorption, and once the medium is saturated it stops adsorbing — it does not gradually get less effective in a safe way, it can begin releasing what it had captured. Saturated wet carbon is also a hospitable environment for bacterial growth. And a clogged filter causes channelling, where water finds a path through and is barely treated at all.

So: replace on the manufacturer’s schedule or by volume, whichever comes first, and do not stretch it because the water still tastes fine. Taste is not an indicator of whether a filter is still removing lead. If a filter has sat unused and wet for weeks — after a holiday, say — flush it thoroughly before drinking, and if it has been months, replace it.

What we looked at

We built this list from current Amazon listings, manufacturer specifications and published certification claims, and the recurring patterns in verified buyer feedback. We have not sent water samples to a laboratory before and after each filter, and we are not going to imply we did. What we did was check whether each product’s performance claims are backed by third-party certification and a published performance data sheet, and then weigh usability, installation difficulty and long-term filter cost.

We weighted heavily against recurring reports of leaks — the failure mode that turns a filter purchase into a flooring repair — against filters that become hard to source, and against systems whose marketing made broad health claims without naming a standard. Every pick holds a customer rating of 4.4 stars or better.

We also deliberately covered four different product types rather than six reverse osmosis systems, because the right answer depends enormously on whether you own your home, what your water report says, and whether your concern is taste or a specific contaminant.

Which type of filter do you actually need?

Reverse osmosis, under-sink

A membrane with pores fine enough to reject dissolved solids, including lead, nitrate, fluoride, PFAS and most everything else. The most thorough option available domestically. The trade-offs are genuine: it produces wastewater alongside the filtered water (modern systems are far better at this than older ones, but the ratio is never zero), it strips beneficial minerals along with the contaminants, it needs a drain connection and usually a hole in the sink or countertop for a dedicated faucet, it requires adequate water pressure, and tank-based systems deliver slowly.

Carbon block, under-sink

A dense activated carbon cartridge plumbed into the cold supply. A good one certified under NSF/ANSI 53 removes lead, cysts, VOCs and chlorine while leaving minerals intact, wastes no water, needs no drain connection, and delivers at full tap flow. It will not remove dissolved salts, nitrate or fluoride, which a membrane would. For most municipal supplies this is the best balance of thoroughness and practicality.

Countertop and pitcher

No plumbing, no installation, nothing to undo when you move. Countertop RO units plug into a socket and are filled manually; pitchers and dispensers sit in the fridge. The compromises are capacity, the need to keep refilling, countertop or fridge space, and — for pitchers specifically — that filtration performance varies enormously between models. A basic pitcher filter is a taste product; a premium one can be certified for lead. Read which you are buying.

Faucet mount

Screws onto the tap in a couple of minutes, switches between filtered and unfiltered, and costs very little. The cheapest route to certified lead reduction, which makes it valuable for renters and for anyone in older housing who wants to act this week rather than next month. Downsides: slow flow, it will not fit pull-out or spray faucets, it makes the tap bulky, and the cartridges are small so they need frequent replacement.

Whole-house

A sediment and carbon system on the incoming main. Worth having if your water is visibly sediment-laden or heavily chlorinated, because it protects appliances and improves every tap and shower. It is not the answer for lead from your own internal plumbing, because the lead is picked up downstream of the filter. Whole-house and point-of-use solve different problems and many homes benefit from both.

What else to know before you buy

Run the cost per gallon, not the sticker price

Cartridges are the real expense. Work out roughly how much drinking and cooking water your household uses per year, look up the rated capacity of each cartridge in the system, and see how many you will buy annually. A cheap system with small expensive cartridges frequently costs more over three years than a more expensive system with long-life ones.

Two other cost traps: proprietary cartridges from small brands may become unavailable, which turns the system into scrap; and RO systems have several stages replaced on different schedules, so read the maintenance table rather than assuming one annual filter.

Check flow rate and pressure before you commit to RO

Reverse osmosis membranes need pressure to work. Most systems specify a minimum incoming pressure, and in a home with low pressure or on a well with a marginal pump you may need a booster pump. Output is quoted in gallons per day, which sounds enormous until you realize a tank system delivers it slowly — filling a large pot can take minutes. Tankless systems, like the Waterdrop pick below, largely solve that and are the reason the category has improved.

Installation reality check

Under-sink systems are a competent DIY job for most people if you have a cold water shut-off valve under the sink, room in the cabinet, and a place for the faucet. Two things routinely catch people out: RO systems need a drain saddle or connection fitted to the waste pipe, and a dedicated faucet usually needs a hole in the sink or countertop. Granite and quartz countertops need a professional to drill. If your sink has an unused sprayer hole, that is your easiest route — check before ordering.

And whatever you fit, turn the water on slowly the first time, then check every joint, then check again after twenty-four hours. Under-sink leaks are found late and cost a great deal.

The 6 best water filters

1. Waterdrop G3P600 Tankless Reverse Osmosis — best overall

The single biggest historical complaint about under-sink reverse osmosis was the tank: a bulky pressure vessel filling most of the cabinet, delivering water slowly, and storing it long enough that people worried about what grew in it. Tankless systems removed that problem, and the G3P600 is the one that brought the idea to a sensible price.

It filters on demand at a high enough rate that filling a jug or a pot feels like using a tap rather than waiting on a machine, and Waterdrop publishes third-party certification for it along with an eight-stage filtration arrangement. There is also a smart display on the faucet showing filter life and water quality, which sounds like a gimmick and is actually the feature that gets filters changed on time. Customer rating is 4.5 stars.

Why it made the list: it is reverse osmosis without the two things that make people dislike reverse osmosis. No tank means far more cabinet space and no stored water; high output means the flow is usable. Add genuine published certification rather than vague claims, and this is the system to buy if you want the most thorough filtration available domestically and can install under the sink.

The drawbacks: tankless means it is electric, so it needs a socket under the sink — check you have one, and understand that a power cut means no filtered water. Like all RO it produces wastewater, and while the ratio is far better than older systems it is not zero, which matters if you are on a septic system or paying for water by volume. It strips minerals, so the water tastes flatter than carbon-filtered water and some people dislike that; Waterdrop sells a remineralisation add-on, or you can choose the iSpring below. It needs a drain connection and a faucet hole. And the multiple stages have different replacement intervals, so read the maintenance schedule properly.

Who it is for: homeowners, anyone whose water report shows dissolved contaminants a carbon block will not handle, and anyone who wants the most complete option with usable flow.

See the Waterdrop G3P600 on Amazon →

2. iSpring RCC7AK-BN — best value reverse osmosis

This has been one of the best-selling under-sink RO systems for years, and the reason is a combination of NSF certification, a sensible six-stage design, and a price well below the tankless generation. The stage that distinguishes it is the alkaline remineralisation cartridge: after the membrane has stripped everything out, this puts calcium, magnesium and other natural minerals back in, which both raises the pH slightly and — more noticeably — makes the water taste like water rather than like nothing.

iSpring has also made small practical choices that show experience. A top-mounted fastener makes filter changes easier in a cramped cabinet, and the first-stage housing is transparent so you can see the sediment being caught, which is a surprisingly effective reminder that the system is working and needs servicing. Customer rating is 4.6 stars across a very large review base.

Why it made the list: it solves the main sensory objection to reverse osmosis at a price most people will accept. RO water without remineralisation does taste flat, and having the stage built in rather than added later is the right answer. The certification, the review volume and the years on the market mean there is very little unknown about this system.

The catch: it is a tank system, so expect a large pressure vessel in the cabinet and a slow trickle rather than a flow — filling a stockpot takes patience. Wastewater ratio is higher than newer tankless designs. Six stages means six things to maintain on varying schedules, and while the top-mounted design helps, this is more maintenance than a single carbon block. It needs a drain saddle and a faucet hole. And alkaline remineralisation is a taste and pH feature, not a health treatment — treat claims beyond that skeptically.

Who it is for: homeowners wanting thorough filtration on a budget, anyone who has tried RO water and found it tasteless, and anyone who values a long track record over the latest design.

See the iSpring RCC7AK-BN on Amazon →

3. Bluevua RO100ROPOT Countertop RO — best for renters

If you rent, the under-sink options above are mostly unavailable to you — drilling a countertop and cutting into a waste pipe is not something most tenancies permit. This is the pick that gives you full reverse osmosis anyway: a countertop unit with a five-stage RO arrangement that plugs into a socket, is filled by hand, and dispenses into a carafe. No plumbing, no drilling, nothing to restore when you move out.

Bluevua has also thought about the two running costs. The system shuts down automatically to save power rather than idling, and the water-to-waste ratio is better than typical tank systems. Customer rating is 4.6 stars.

Why it made the list: it removes the single biggest barrier to good filtration for a very large group of people. A renter in older housing with a lead concern has, until recently, had a choice between a faucet mount and bottled water; a countertop RO unit is a better option than either. It is also the right answer for anyone in a home where the cabinet under the sink is full, or where the countertop cannot be drilled.

Where it falls short: it occupies real countertop space, and it is not small — measure before ordering, particularly under wall cabinets. It has to be filled manually, which is a chore you will do several times a day in a busy household, and the reservoir capacity means it is not suited to filling large pots or to entertaining. It needs a power socket and, like the tankless system above, does nothing in a power cut. The waste water goes into a separate chamber that you empty, which is an extra step people underestimate. And as with all RO, minerals are stripped, so expect flatter-tasting water.

Who it is for: renters, students, anyone in older housing with a lead concern and no ability to modify plumbing, and anyone who moves often.

See the Bluevua RO100ROPOT on Amazon →

4. Frizzlife Under Sink System — best under-sink filter without reverse osmosis

For a great many homes on municipal water, this is actually the smartest purchase on the page, and it deserves more attention than reverse osmosis usually leaves it. It is a carbon block system carrying certification under NSF/ANSI standards 42, 53 and 401 — which means it is verified for aesthetic effects, for health-related contaminants including lead, and for emerging contaminants such as pharmaceutical residues.

What it gives you that RO does not: full tap flow rather than a trickle, no wastewater at all, no electricity, no drain connection, no tank in the cabinet, and water that keeps its natural mineral content and therefore tastes better to most people. The cartridge is a half-micron block and the design is aimed at straightforward DIY installation. Customer rating is 4.5 stars.

Why it made the list: because for the most common real-world problem — chlorinated municipal water plus a lead risk from your own plumbing — a certified carbon block solves it more elegantly than a membrane does. You get certified lead reduction, you do not waste water, you do not strip minerals, and you do not give up cabinet space. Reverse osmosis is the more thorough technology; this is often the more appropriate one.

What owners complain about: it will not remove dissolved salts, nitrate, fluoride or total dissolved solids — if your water report flags any of those, or if you are on a well with agricultural runoff, you need the membrane and this is not the right choice. Carbon capacity is finite and the cartridge must be replaced on schedule; a half-micron block also clogs faster on sediment-heavy water, so a sediment pre-filter is worth considering. It still needs a cold water shut-off under the sink and space in the cabinet. And Frizzlife is a smaller brand than iSpring or Waterdrop, so check cartridge availability before committing.

Who it is for: most homes on municipal water, anyone whose concern is chlorine and lead rather than dissolved solids, anyone who dislikes RO water’s flat taste, and anyone who does not want a tank or a drain connection.

See the Frizzlife under sink system on Amazon →

5. Brita XL 27-Cup Dispenser — best pitcher for a family

Pitchers get dismissed by people who have moved on to plumbed systems, and that is a mistake, because the reason most pitchers disappoint is capacity rather than filtration. A 10-cup pitcher in a household of four is refilled constantly, resented, and eventually abandoned. A 27-cup dispenser is refilled once or twice a day and simply works.

This one pairs that capacity with Brita’s higher-performance BritaPlus filter, which the company states reduces roughly twice the contaminants of its standard cartridge while retaining minerals and electrolytes. Brita is also the brand with the widest cartridge availability of anything on this page — you can buy replacements in any supermarket, which over five years matters more than people expect. Customer rating is 4.5 stars.

Why it made the list: it is the pick for anyone who wants better water this week with no installation, no countertop footprint and no commitment. It is also the sensible companion to a whole-house sediment system, and the right answer for a shared house, an office kitchen or a holiday let where plumbing changes are not happening.

The downside: read the performance data sheet for the specific cartridge you are buying, because Brita sells several and they differ substantially — the standard filter is largely a taste-and-chlorine product, and only the higher-specification cartridges address a wider list. If lead is your concern, confirm the cartridge is certified for lead specifically rather than assuming. Filtration is slow by gravity, so a freshly refilled dispenser is not immediately full of filtered water. It takes up a shelf in the fridge, and 27 cups of water is heavy to lift when full. And cartridge cost per gallon is higher than any plumbed system here.

Who it is for: families, renters, shared houses, offices, and anyone who wants an improvement today with no tools.

See the Brita XL 27-Cup dispenser on Amazon →

6. PUR Plus Faucet Mount — cheapest way to reduce lead

This is the pick with the best ratio of benefit to cost and effort on the entire page, and it belongs here precisely because it is unglamorous. It screws onto a standard tap in about two minutes with no tools, switches between filtered and unfiltered with a lever so you are not wasting cartridge life rinsing dishes, and it is certified for lead reduction.

For a renter in an older building who has just read their water report and would like to do something about lead before the weekend, this is the answer. Customer rating is 4.4 stars.

Why it made the list: because the best filter is the one that is actually installed. A certified faucet mount fitted today does more good than a reverse osmosis system you are still researching in three months, and for a small fraction of the cost. It is also a sensible stopgap: fit one now, and decide about a plumbed system at your leisure.

What you give up: it will not fit pull-out, pull-down or spray faucets, which rules out a large share of modern kitchens — check your tap before ordering. Flow is slow, and filling a kettle takes noticeably longer than from the tap. The cartridge is small, so replacements are frequent and the cost per gallon is the highest here. It makes the end of the tap bulky and heavy, which can stress an older faucet, and the housing is a plastic assembly that is the most likely thing here to eventually drip. And as always, check the performance data sheet for which contaminants the specific cartridge is certified against.

Who it is for: renters, tight budgets, anyone wanting certified lead reduction immediately, and anyone testing whether filtered water changes their habits before spending more.

See the PUR Plus faucet mount on Amazon →

Finding out what is in your water

• On municipal water: look up your utility’s annual water quality report, often called a Consumer Confidence Report. It is free, usually online, and tells you what was found at the treatment plant and in the distribution system.
• Remember the report stops at your property line. Lead from your own service line, solder or fixtures will not appear in it. If your building predates the mid-1980s, assume that is worth investigating.
• On a private well: nobody is testing it for you. A laboratory test is really necessary, and many local health departments can advise on which tests matter in your area — commonly bacteria, nitrate, arsenic and whatever local geology or land use suggests. Retest periodically.
• A home test kit is a screening tool, not a laboratory. Useful for a quick indication of hardness or chlorine; not something to base a lead decision on.
• A TDS meter measures dissolved solids, not safety. High TDS can be entirely harmless minerals, and low TDS does not mean the water is free of contaminants. It is useful for checking whether an RO membrane is still working, and for very little else.
• If you get a result that worries you, talk to your local health department or your doctor rather than working it out from product marketing.

Living with a filter

• Set a reminder for cartridge changes. Calendar entry, phone reminder, or a note on the cabinet door. Taste is not an indicator.
• Flush a new cartridge properly. Most need several minutes or a few gallons run through to clear carbon fines. The first water will look cloudy or grey; that is normal and it should clear.
• Run the tap before drinking if water has been standing, particularly first thing in the morning and especially in older plumbing. Use the water for plants rather than pouring it away if that bothers you.
• Never filter hot water unless the system explicitly allows it. Hot water damages carbon and membranes, and hot tap water leaches more from pipes in the first place.
• After a holiday, flush thoroughly. Water standing in a wet filter for two weeks should not be the water you drink on your return.
• Sanitise pitchers and reservoirs. Wash the jug and lid regularly; biofilm forms in any container that is always damp.
• Check under-sink joints after installation and again a day later, then occasionally thereafter. A slow leak found late is the expensive failure in this category.

Easy mistakes to make

• Buying before checking your water report. The single most common error. You cannot choose a filter without knowing the target.
• Treating “tested to NSF standards” as certification. It is not. Look for certified by NSF, WQA or IAPMO, under a named standard, for named contaminants.
• Assuming NSF 53 means lead. Certification under 53 is contaminant-specific; check the actual list.
• Stretching filter life. A saturated carbon filter can release what it captured and can harbor bacteria.
• Relying on a domestic filter during a boil water notice. Follow the notice.
• Expecting a whole-house filter to fix lead at the tap. The lead is picked up downstream of it.
• Confusing a softener with a filter. Different job entirely, and it adds sodium.
• Buying a faucet mount for a pull-down tap. It will not fit. Check first.
• Choosing a system with proprietary cartridges from an unknown brand. If the cartridges vanish, so does the system.

Frequently asked questions

Do I need a water filter at all?

If you are on a well, or your building has old plumbing, or your utility report flags something, or you simply dislike the taste of your tap water, a filter is worth having. If you are on a well-regulated municipal supply in modern plumbing and are happy with the taste, a filter is a preference rather than a necessity. The way to find out which applies to you is to read the water quality report rather than to guess.

Is reverse osmosis water bad for you because it removes minerals?

The mineral content of drinking water is a small contributor to overall mineral intake for most people eating a normal diet, so removing it is not generally a health concern. The clearer, less contested issue is taste: demineralised water tastes flat to most people, which is why remineralisation stages exist and why many buyers add one. If you have a specific medical reason to be careful about mineral or electrolyte intake, that is a question for your doctor rather than a product guide.

Does boiling water filter it?

Boiling kills or inactivates bacteria, viruses and parasites, which is why boil water notices exist and why boiling is the right response to one. It does nothing about lead, nitrate, PFAS or most chemicals — and because boiling evaporates water, it slightly concentrates dissolved contaminants. Boiling and filtering address different problems and neither replaces the other.

Do refrigerator filters do a good job?

The manufacturer’s own filters generally carry real certification and are worth their cost. The cheap aftermarket alternatives are where care is needed: many carry no meaningful certification, and some perform poorly while looking identical. If you use a fridge filter, check that the one you buy is certified for the contaminants you care about, and replace it on schedule — fridge filters are among the most commonly neglected in any home.

How often should I really change the filter?

Follow whichever comes first of the manufacturer’s time interval and its volume rating. Real water use varies enormously, so a filter rated for a certain number of gallons may last three months in one house and a year in another. Sediment-heavy or heavily chlorinated water shortens life. Do not extend the interval because the water still tastes acceptable.

Will a filter remove hard water scale?

Standard carbon and RO cartridges are not scale treatments. Reverse osmosis does remove hardness minerals from the water it produces, so an RO tap will not scale your kettle — but it only treats the water going through it, not your shower or your washing machine. For whole-house hardness you need a softener or a scale-inhibiting system, which is a different product solving a different problem.

Are countertop RO units as good as under-sink ones?

The filtration technology is essentially the same and good countertop units perform comparably. What you give up is convenience and capacity: manual filling, a waste reservoir to empty, limited volume, and countertop space. What you gain is that you can have reverse osmosis in a rented flat without touching the plumbing, which for many people is the difference between having it and not.

Our call

Before anything else, read your water quality report — or test your well. It costs nothing and it turns this from a guess into a decision.

If that report points to dissolved contaminants and you own your home, the Waterdrop G3P600 is the best system here: reverse osmosis without the tank or the trickle. On a tighter budget, the iSpring RCC7AK-BN does the same job more slowly and puts the minerals back. If you rent, the Bluevua RO100ROPOT gives you the same technology with no plumbing at all.

But for a great many homes the honest answer is the Frizzlife under-sink carbon block — certified for lead and a long list of other contaminants, at full tap flow, with no wastewater and no loss of minerals. And if you want something today rather than a project, the Brita XL dispenser or the PUR Plus faucet mount will improve your water this afternoon for very little money, which counts for more than a better system you have not bought yet.

Whatever you choose, change the cartridges on schedule. An overdue filter is not a slightly worse filter — it is a false sense of security, and that is the one outcome worth avoiding entirely.

For more on the rest of your home environment, see our guides to the best air purifiers, the best dehumidifiers, and the best humidifiers.

Also worth reading: our guide to the best shower heads.

Also worth reading: our guide to the best water softeners.

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Also worth reading: our guide to the best bidets.

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