Reviews guides

How we score water-treatment equipment

Reviews here measure what a spec sheet can prove: removal performance, capacity against real household use, cost per gallon over five years, and how the unit behaves when something fails. Brand reputation is a tiebreaker, not a criterion.

Criterion	Weight	What moves the score
Certified removal	30%	NSF/ANSI 42, 44, 53 or 58 listing for the claimed contaminants
Capacity vs household	25%	Grains or gallons sized honestly for 2–5 people
Five-year cost per gallon	20%	Equipment, install, consumables and service parts
Service and parts	15%	Control-head parts availability, membrane and cartridge standardisation
Warranty and support	10%	Resin and valve coverage, response time

Weights are published so a reader can disagree and recompute. A unit with excellent removal and a proprietary cartridge sold only through dealers scores lower than a comparable unit that takes a standard 10-inch filter.

The brand landscape, by job

Category	Names you will meet	What to check
Dealer-installed softeners	Culligan, Kinetico, local dealers	Monthly rental vs purchase; proprietary resin tanks
Online softeners	Fleck-based units, Aquasana, iSpring	Valve model, resin volume, warranty on the valve
Under-sink RO	iSpring, AquaTru, Waterdrop	NSF 58 listing, membrane cost, tank size
Gravity and countertop filters	Berkey, Brita, ZeroWater	Cost per gallon, filter life, certified claims
Whole-house carbon	Aquasana, SpringWell, local plumbers	GPM rating at peak demand, cartridge standard

Dealer models are not automatically worse, but the pricing model differs: a $4,000 installed system with a service contract is a different product from a $1,400 valve-and-tank unit a plumber installs. Compare the five-year cost, not the first invoice. The cost hub carries the arithmetic.

Red flags in a listing

• "Removes up to 99% of contaminants" with no contaminant list and no NSF number.
• Grain capacity quoted without resin volume — the two should agree.
• Salt-free products described as softeners.
• RO systems with no membrane replacement price published.
• Warranty that covers the tank but not the control valve.
• Flow rate quoted in gallons per day instead of gallons per minute for whole-house units.

What this hub does not review

We do not score installers, and we do not rank a brand on a single failure report. We also do not review units without a published spec sheet — if the removal claims cannot be checked against a certification, the product gets a note saying so rather than a score.

Start with the systems hub to understand what each category does, the problems hub to confirm what your water actually needs, and the comparison hub for the four decisions buyers face most.

Are expensive softeners worth it?

Only when the valve, resin volume and warranty justify the difference. A $2,500 unit and a $900 unit can both soften water; the expensive one should show a metered valve, a larger resin bed and a parts network.

Do you accept paid placements?

No. Rankings follow the criteria table; affiliate links are disclosed on every page and never move a score.

Why is there no star rating?

A star hides the criterion that decided it. The tables show the weights and the values, so you can re-rank for your own water.

How to read a review on this site

Every review names the criterion that decided it. Where a claim could not be checked against a certification listing or a spec sheet, the page says so instead of filling the gap — a filter with no NSF number gets a note, not a score. That is also why the tables show weights: if your water is well water with iron, you can raise the removal criterion and re-rank the list yourself.

Prices in reviews are the band we verified in the month shown on the page. They are not live retail prices, and a unit that is excellent value at $400 can be poor value at $700 after a tariff change. Check the current price and the certification on the product page before buying.