# WaterCriteria

> Water filter and treatment guides: reverse osmosis, whole-house and under-sink filters, softeners, well-water systems and testing, compared by certification, capacity and cost to own.

WaterCriteria publishes water filtration and treatment reviews, buying guides and reader discount codes. Every review states who the product suits, the current price from the brand's own store, and any active reader code.

## Key pages
- [Reviews](https://watercriteria.com/reviews): every product we recommend
- [Buying guides](https://watercriteria.com/guides): how to choose
- [Glossary](https://watercriteria.com/glossary): water filtration and treatment terms defined
- [How we test](https://watercriteria.com/testing-methodology)

## Topics
- [Drinking-water filters](https://watercriteria.com/category/drinking-water-filters): Point-of-use filters for the kitchen: pitchers, faucet mounts, countertop units and under-sink carbon systems.
- [Reverse osmosis](https://watercriteria.com/category/reverse-osmosis): Under-sink tank and tankless RO, countertop RO, remineralization stages and membranes.
- [Whole-house & softeners](https://watercriteria.com/category/whole-house): Sediment, carbon and specialty-media systems at the main line, salt-based softeners and salt-free conditioners.
- [Well water](https://watercriteria.com/category/well-water): Iron and manganese filters, sulfur treatment, UV disinfection and well-specific testing.
- [Testing & parts](https://watercriteria.com/category/testing): Lab test kits, strips, TDS and hardness meters, replacement cartridges and installation parts.
- [Installation & maintenance](https://watercriteria.com/category/installation): Filter housings, fittings, valves, drain saddles, booster pumps, UV lamps and service tools.

## Buying guides
- [How to Choose a Whole-House Water Filter](https://watercriteria.com/guides/how-to-choose-a-whole-house-water-filter): Pick a whole-house filter by matching its media to the problem in your water, then size it for your home's peak flow, usually 6 to 12 gallons per minute. Use sediment prefilters for grit, carbon for chlorine taste (catalytic carbon for chloramine), and dedicated iron, manganese or sulfur filters on well water. UV disinfection needs clear, low-iron water ahead of it.
- [Pitcher vs Under-Sink Water Filter: Cost, Capacity and Performance](https://watercriteria.com/guides/pitcher-vs-under-sink-water-filter): Pitchers are cheap to buy, need no installation and suit renters, but their cartridges filter only about 40 to 100 gallons each and refilling is slow. Under-sink filters cost more upfront and need a simple plumbing connection, but deliver filtered water on tap, last hundreds of gallons per cartridge and often cost less per gallon. Check that whichever you choose is certified for your contaminants.
- [Reverse Osmosis vs Carbon Filter: Which Problem Does Each Solve?](https://watercriteria.com/guides/reverse-osmosis-vs-carbon-filter): Carbon filters reduce chlorine, taste and odor, and certified models also reduce lead, some VOCs and PFOA/PFOS. Reverse osmosis pushes water through a membrane that also removes dissolved solids such as fluoride, arsenic, nitrate and salts. Choose carbon if chlorine taste or certified lead reduction is the goal; choose RO when your test shows dissolved contaminants carbon cannot remove.
- [Water Filter Certifications Explained: NSF/ANSI 42, 53, 58 and 401](https://watercriteria.com/guides/water-filter-certifications-nsf-standards): A water filter's certification tells you which contaminants it was independently shown to reduce. NSF/ANSI 42 covers taste, odor and chlorine; 53 covers health contaminants such as lead, cysts and some PFAS; 58 covers reverse osmosis systems; 401 covers emerging compounds such as some pharmaceuticals. Always check the listing for the exact model and the exact contaminant you care about.
- [Water Softener Sizing: How Many Grains Do You Need?](https://watercriteria.com/guides/water-softener-sizing-guide): Multiply your hardness in grains per gallon by your household's daily water use to get grains removed per day, then size the softener to regenerate about every seven days. A family of four using about 300 gallons a day with 15 gpg hardness removes 4,500 grains a day, or about 31,500 a week, so a 32,000 to 40,000 grain unit fits. Add about 4 to 5 gpg for each ppm of iron.
- [Well Water Testing: What to Test For and How Often](https://watercriteria.com/guides/well-water-testing-guide): Test a private well at least once a year for total coliform bacteria, nitrate, total dissolved solids and pH, as the CDC and EPA recommend. Add tests for arsenic, lead, manganese, uranium or radon based on your area and plumbing, and retest after flooding, repairs or a change in taste, smell or color. Use a state-certified lab.

Contact: info@watercriteria.com