Water
Home water treatment: diagnose a symptom or lab result, size a softener or filter, match a model number to its part, and compare the units worth a shortlist.
Every page under this heading is about the water coming into a house: what a symptom or a test result means, what size of equipment it takes, which cartridge fits the housing you already own, and which units are worth a shortlist. Limits are cited to EPA, NSF/ANSI and extension services by number.
Sizing calculators for home water treatment: grain capacity, flow rate, micron rating and more, with the formula shown.
15 calculators
Diagnostic guides: a symptom or a lab result in, a treatment class out, with the EPA or NSF limit cited by number.
57 guides
Model number to replacement part: which cartridge, membrane or lamp fits, on what interval, and which cross-fit alternatives exist.
49 parts
System comparisons segmented by the problem being solved, chosen against a stated method from published specifications.
30 reviews
Well water 32 pages
Diagnose
Well pump not working, no water: 6 checks
No water from a well: read the gauge against the switch cut-in (30 or 40 psi), check the breaker, the switch contacts, the tank pre-charge 2 psi below cut-in.
Diagnose
Well winter freeze checklist, part by part
A well freeze checklist: Minnesota code buries supply pipe 12 inches below the local frost depth, and a pitless adapter attaches 6 or 7 feet down.
Diagnose
Flooded well: what to do first, in order
A flooded well: power off and an electrician first, purge until clear, then disinfect, then a certified lab test at 7 to 10 days, 2 to 4 weeks and 3 to 4 months.
Diagnose
Uranium or radon in well water: limits and removal
EPA's uranium MCL is 30 ug/L, removed by anion exchange or RO. Radon in water has no final MCL, only a 1999 proposal; aeration vents it.
Diagnose
Arsenic in Well Water: Limit and Treatment
EPA's arsenic MCL is 10 µg/L (0.010 mg/L). Arsenic V leaves via RO, anion exchange or adsorptive media; arsenic III needs oxidation first.
Diagnose
Algae in water filter housing: cause and fix
Green growth in a clear housing is algae on light: fit an opaque sump. Rusty or oily slime is iron bacteria: shock chlorinate at 200 ppm max per MDH.
Diagnose
Sediment and turbidity in well water: which filter
Cloudy well water above 5 NTU shows in a glass (NDSU); UV needs under 1 NTU (VIQUA). Sand: a spin-down screen. Silt and clay: a 5 micron pleated cartridge.
Diagnose
Nitrate in well water: the 10 mg/L limit and fixes
Nitrate in well water above EPA's MCL of 10 mg/L as N (45 mg/L as nitrate) needs RO, anion exchange or distillation. Boiling and softeners remove none.
Diagnose
Coliform-positive well water: meaning and fixes
A coliform-positive well test means the sanitary barrier failed: shock chlorinate at up to 200 ppm, retest in 2 to 4 weeks, then UV at 40 mJ/cm2 if it returns.
Diagnose
What to test well water for: the annual panel
A private well needs coliform, nitrate, TDS and pH every year at a certified lab (CDC, EPA). Nitrate limit 10 mg/L as N. Which symptom adds which test.
Diagnose
Tea-colored well water: tannins vs iron, and fixes
Tea-colored well water that stays colored after a glass sits overnight is tannins, not iron. EPA lists color at 15 units; the fix is anion resin, carbon or RO.
Diagnose
Rotten egg smell in well water: hydrogen sulfide
Hydrogen sulfide has no EPA limit; the nose finds it at 0.05 to 0.1 mg/L. Hot tap only means the heater anode, both taps means the well, and the mg/L picks the fix.
Diagnose
Iron in well water: how much, and what treats it
Rust stains on a private well mean iron at or above the EPA secondary standard of 0.3 mg/L. Which form it is, and which treatment class fits each mg/L range.
Diagnose
How to shock chlorinate a well: amount and time
Shock chlorinate a well at 50 to 200 ppm with plain 6% or 8.25% bleach, hold it 2 to 6 hours or overnight, flush to 0 ppm, retest in 2 to 4 weeks.
Diagnose
Blue-green stains: low pH well water and the fix
Blue-green stains on a well are copper dissolved by low-pH water. EPA's pH range is 6.5 to 8.5; an acid-neutralizing filter treats down to pH 5.3.
Diagnose
Black stains from well water: manganese and fixes
Black stains on a private well mean manganese above EPA's secondary standard of 0.05 mg/L. Why it resists iron treatment, and which class fits each mg/L range.
Size
Well pump size calculator: GPM by fixture count
Pump gpm = fixtures x 1 gpm (Water Systems Council, Red Lion): an 8-fixture house takes an 8 gpm pump, never above the well yield, submersible past 90 ft.
Size
How much bleach to shock a well: calculator
Casing gallons = 0.041 x diameter squared x feet of water. A 6-inch well with 100 feet holds 148 gal and takes about 4 cups of 6% bleach at 100 ppm.
Size
Iron filter size calculator: tank vs pump GPM
Largest tank = pump GPM divided by the media backwash rate. A 10 GPM pump backwashes a 12-inch Birm tank (9.4 GPM needed) and stalls on 13-inch (11.1 GPM).
Size
Acid neutralizer size calculator: calcite tank
Bed area = peak gpm / 5 for calcite (pH 6.0-7.0) or / 3 for a calcite-Corosex blend. A 2.5 gpm home at pH 6.8 needs a 10x54 tank and 98 lb of calcite.
Size
UV water purifier size calculator: GPM by dose
Peak gpm = bathrooms x 2.5 + 2.2; a 2-bath house pulls 7.2 gpm. Size to the 40 mJ/cm2 Class A rating: a VIQUA VH410 sold as 18 GPM is 14 gpm at that dose.
Match
Well Pump Pressure Switch Replacement 30-50, 40-60
Read the pressure pair off the old switch. Square D Pumptrol FSG2J20 is 20-40, FSG2J21 is 30-50, FSG2J24 is 40-60 psi; add M4 for a low-pressure cutoff.
Match
Well Pressure Tank Cross-Reference by Model
Amtrol WX-202, Water Worker HT-20B, Goulds V60, Flexcon WR 60 and Red Lion RL20A share the 20-gallon, 1 in slot. Drawdown at 40/60 psi: 5.3 to 5.9 gal.
Match
Viqua UV Lamp Cross-Reference: S330RL to 602806
Viqua S463RL fits the S5Q-PA, S330RL the S2Q-PA, 602805 the D4, 602806 the E4. Each lamp is rated 9,000 hours, changed yearly; sleeve cleaned every 12 months.
Compare
Best well pump: jet vs submersible by spec sheet
Depth to water picks the type: under 25 ft a shallow jet (Red Lion RJS-75, 7.2 GPM at 25 ft, 40 psi), 25 to 90 ft a convertible, deeper a 4 in submersible (RL12G10).
Compare
Best well pressure tank, sized by drawdown and GPM
Maker sheets compared: Amtrol WX-203 prints 8.6 gal drawdown at 40/60, WX-202 5.4, WX-250 11.8; sized on pump GPM and a 1 minute run. Pre-charge 2 psi below cut-in.
Compare
Best acid neutralizer filter for low pH well water
Calcite treats pH 5.0 to 7.0, a calcite/Corosex blend reaches 4.5, per Clack. Backwashing Fleck 5600SXT vs upflow tanks by tank size, GPM and media.
Compare
Best whole house water filter for well water, by spec
Pick: iSpring WGB32BM, rated to 3.0 mg/L iron and 1.0 mg/L manganese, 15 GPM, 100,000 gallons. Above 10 mg/L combined, a cartridge is the wrong tool.
Compare
Best water test kit for well and city water
A mail-in certified lab kit (Tap Score Essential, 54 analytes, 5 business days) beats strips: no strip reads a coliform count, lead at 15 ppb or PFAS.
Compare
Best UV water purifier for well water, by spec
Viqua VH410: 18 GPM at 30 mJ/cm2, 14 GPM at 40 mJ/cm2, 9,000-hour lamp. No unit here is NSF/ANSI 55 Class A; the VH410-V is Class B at 14 GPM.
Compare
Best spin down sediment filter for well water
iSpring WSP-50: 50 micron stainless mesh, 20 GPM, 25 to 80 psi. Auto-flush: WSP50ARB, 25 GPM. High flow: Rusco 1-1/2 in, 18 to 100 GPM, 150 psi.
Compare
Best iron filter for well water, by published spec
Iron plus manganese 3 to 10 mg/L: an AIO such as the AFW AIS10-25SXT (10 ppm iron) or Birm at pH 6.8 to 9.0. Under 3.0 ppm with no drain line: the iSpring WGB32BM.
Drinking water 28 pages
Diagnose
Brita vs PUR vs ZeroWater: certified lead, gallons
Brita Elite (WQA, 120 gal), PUR PLUS (WQA lead rows, 40 gal) and ZeroWater (IAPMO R&T, 15 gal) carry a certified lead claim; Brita Standard and plain PUR do not.
Diagnose
Water filter Black Friday and Prime Day deal check
A discounted water filter is a deal only if it carries NSF/ANSI 42, 53 or 58 for your contaminant in a certifier's listing. Black Friday: November 27, 2026.
Diagnose
Lead service line notice: what the letter means
The annual lead service line notice goes out by 31 December. What lead, GRR and unknown mean, and the 30-day clock you start by disputing the category.
Diagnose
Lithium in drinking water: no MCL, 10 ug/L HRL
EPA's UCMR 5 found 2,747 of 10,313 public water systems above the 10 ug/L lithium reference level. That level is a screening value, not an MCL.
Diagnose
UCMR 5: look up your water system's PFAS
EPA's final UCMR 5 dataset, released August 2026, covers about 10,130 water systems. Find your PWSID, read the result, and know why a non-detect means below 4 ppt.
Diagnose
Chromium-6 in California tap water: 10 ppb MCL
California's hexavalent chromium MCL is 0.010 mg/L (10 ppb), effective 1 October 2024. Compliance began 1 October 2026 for systems with 10,000 or more connections.
Diagnose
TDS meter reading: what it means, what is too high
A TDS pen reads conductivity times a factor, not contaminants. EPA's secondary standard is 500 mg/L; NHMRC rates 0 to 600 mg/L good for taste.
Diagnose
Reverse osmosis waste water ratio and drain
Under-sink RO wastes 4 to 5 gallons per gallon made per APEC. Whole-house RO reject should not go to a septic system, per UMN Extension.
Diagnose
Microplastics water filter: what removes them
EPA's draft CCL 6 (April 2026) lists microplastics with no limit. NSF/ANSI 401 is the only test: 85% reduction of 0.5 to 1 micron particles.
Diagnose
How to read a water test report: ND, MCL, units
A passed report means every MCL was met. Iron 0.3 mg/L, manganese 0.05 and pH 6.5 to 8.5 are unenforced secondary standards a lab may not flag.
Diagnose
EPA drinking water standards table: every MCL
Lead 15 ug/L action level, nitrate 10 mg/L, arsenic 0.010 mg/L, PFOA and PFOS 4.0 ppt, TDS 500 mg/L secondary: every EPA MCL and secondary standard, one table.
Diagnose
Does reverse osmosis remove it? Contaminant table
RO removes a contaminant only when its NSF/ANSI 58 or 53 listing names it: lead passes at 5 ppb, PFOA/PFOS at 20 ppt. Bacteria is NSF/ANSI 55 UV, not RO.
Diagnose
Reverse osmosis remineralization: do you need it?
RO strips 90 to 99% of dissolved solids per APEC. EPA's pH 6.5 to 8.5 and TDS 500 mg/L are ceilings with no mineral floor, so remineralize for taste.
Diagnose
PFAS in tap water: the 4.0 ppt limit and filters
EPA's 2024 rule sets PFOA and PFOS at 4.0 ppt. Only filters certified to NSF/ANSI 53 or 58 with a PFOA/PFOS claim are tested for it, to a 20 ppt protocol.
Diagnose
Lead in tap water: service lines and which filter
EPA's lead action level is 15 ppb, dropping to 10 ppb on 1 November 2027. Three checks find a lead service line; NSF/ANSI 53 or 58 filters pass at 5 ppb.
Diagnose
Fluoride in tap water: your level and which filters
Utah and Florida stopped adding fluoride in 2025; EPA's MCL stays 4.0 mg/L. How to read your CCR, and which filter classes reduce fluoride, and which do not.
Size
Water distiller cost per gallon calculator: kWh
kWh per gallon = watts x hours per batch / gallons. An 800 W distiller at 4 hours a gallon uses 3.2 kWh, about 59 cents at EIA's July 2026 18.31 cents per kWh.
Match
Aquasana AQ-5200 Replacement Filters: AQ-C2-R
Aquasana Claryum 2-Stage AQ-5200 and AQ-6200 take the AQ-C2-R set (AQ-5200R): 500 gallons or 6 months, 0.5 gpm, WQA to NSF/ANSI 42, 53, 401 per Aquasana.
Match
AquaTru Replacement Filters: Classic and Carafe
AquaTru Classic filters last 6 months/600 gal (Pre/Carbon), 2 years/1,200 gal (RO), 1 year/600 gal (VOC). Carafe filters are rated 300 gal and do not swap.
Match
Reverse Osmosis Tank Replacement: Fit and Precharge
Standard RO tanks: 1/4 in NPT, 4 gal nominal, about 3.2 gal usable, factory precharge 5 to 10 psi by maker. Which tank fits, and how to swap it.
Match
Reverse Osmosis Membrane Replacement: 1812 Sizes
A 1812 RO membrane is 11.74 x 1.75 in per DuPont's data sheet: FilmTec TW30-1812, iSpring MC7 and MC1, APEC MEM-ES-50 and Express Water ROM all fit.
Match
Waterdrop G3P800 Replacement Filters
The Waterdrop G3P800 takes the WD-G3-N1CF (6 months), WD-G3-N3CB (12 months) and WD-G3P800-N2RO membrane (24 months). Only the membrane differs across the G3 line.
Match
iSpring RCC7 Replacement Filters by Stage
iSpring RCC7 stages take FP15, FG15, FC15 (10 in, 5 micron) every 6 months, the MC7 membrane every 2-3 years, FT15 yearly. F7-GAC fits RCC7, F9K fits RCC7AK.
Match
Brita Filter Compatibility: Standard, Elite, Stream
Brita Standard (OB03) and Elite (OB06) fit every Brita pitcher except Stream and interchange: 40 gal vs 120 gal. Stream (OB05) fits only 3 models.
Match
APEC ROES-50 Replacement Filters and Cross-Fits
The APEC ROES-50 takes FILTER-SET-ES (stages 1-3, every 6-12 months) and a MEM-ES-50 membrane every 2-4 years. The ROES-PH75 needs the ESPH sets, not the ES ones.
Compare
Best countertop water distiller, US, UK/EU, Japan
Megahome MH943SBS is the US pick: 580 W, 1 gallon per 5.5 hours, glass collection, UL listed, 1 year. Eight 120 V, 230 V and 100 V units on maker spec.
Compare
Best water filter for fluoride removal, by spec
iSpring RCC7AK: 97.4% fluoride reduction under NSF/ANSI 58, 75 GPD. Clearly Filtered pitcher: >99.54%, maker-published, not certified. Who should skip.
Compare
Best water filter pitcher: NSF/ANSI 53 lead and PFAS
Brita Elite is the only pitcher filter here WQA certified to NSF/ANSI 42, 53 and 401: 120 gallons a filter, about $0.17 a gallon. Rivals are tested, not certified.
Water softeners 25 pages
Diagnose
Water softener vs water filter: the difference
A softener swaps calcium and magnesium for sodium under NSF/ANSI 44 and leaves chlorine, lead and PFAS alone. A carbon filter (NSF/ANSI 42 or 53) does the reverse.
Diagnose
How long a water softener lasts: repair or replace
No maker document read here prints a lifespan. Pentair warrants Fleck valves 5 years; Dow gives resin 10 years under 0.2 ppm chlorine, 6 at 1 ppm.
Diagnose
Water softener Black Friday deal check: sizing
A softener deal is only real if the grain capacity fits: gpg (plus 5 per ppm iron) x people x 75 gal x days. The box number is the max-dose capacity.
Diagnose
Humidifier white dust: cause and what stops it
White dust from an ultrasonic humidifier is tap-water minerals in the mist, per EPA. Distilled or RO water stops it; softened water only swaps calcium for sodium.
Diagnose
Are water softeners banned where I live?
No US state bans residential water softeners. California HSC 116786 lets a local agency prohibit installation by ordinance, and only prospectively.
Diagnose
White flakes in water or ice: what they are
White flecks that fizz in vinegar are hardness scale: 1 gpg is 17.1 mg/L per MSU Extension. Floating plastic curls are dip tube; amber beads are resin.
Diagnose
Too much water in brine tank: normal level, causes
A brine tank holds about 1 inch over the grid (Fleck) or 2 to 5 inches (GE) by design. Higher means a plugged injector or drain line; check in that order.
Diagnose
Water softener not using salt: salt bridge diagnosis
A salt bridge is the usual cause. Pentair's 5600SXT manual says keep the tank below half-full, break the crust with a broom handle and wait 2 hours.
Diagnose
Fleck 5600SXT settings: capacity and hardness
Capacity = resin cu ft x grains per cu ft (1.0 cu ft at 8 lb = 22,000 grains), hardness in tested gpg, and metered regeneration, not a timer.
Diagnose
Salt-free water conditioner vs softener
An NSF/ANSI 44 softener drops hardness under 1 gpg. A TAC salt-free conditioner leaves it unchanged; its only pass mark is IAPMO Z601's 70% less-scale test.
Diagnose
White scale on faucets: how hard your water is
White crust on faucets and kettles is hardness scale. Hardness in gpg and mg/L (1 gpg = 17.1 mg/L), the USGS bands, and why 7.0 gpg is the line for a softener.
Size
Softened water sodium calculator: mg per glass
Sodium added = 8 mg/L per gpg of hardness removed (NDSU). 15 gpg softened water carries 120 mg/L: 28 mg per 8 oz glass, 240 mg in 2 L a day.
Size
Water softener salt usage calculator: bags per year
Salt per regeneration = resin cu ft x dose (6, 10 or 15 lb/cu ft). A 1 cu ft unit at 10 lb, 4 people, 10 gpg uses about 406 lb a year: ten 40 lb bags.
Size
Water hardness unit converter: gpg, ppm, dH, mmol/L
1 gpg = 17.118 mg/L as CaCO3, 1 dH = 17.848, 1 fH = 10, 1 Clark = 14.254, 1 mmol/L = 100.09. Convert any hardness unit to the others and read the USGS band.
Size
Softener resin volume to grain capacity calculator
Usable grains = resin cu ft x grains per cu ft at the salt dose. 1.0 cu ft of 8% resin gives 20,000 grains at 6 lb, 24,000 at 10 lb. Calculator and tank table.
Size
Water softener size calculator: grain capacity
Grains = people x 75 gal/day x (gpg + 5 per mg/L iron) x days between regenerations. 4 people at 10 gpg for 7 days is 21,000 grains. Calculator and the size table.
Match
Water softener resin: 8% crosslink guide
Refill 1 cu ft of 8% crosslink cation resin per rated cubic foot (ResinTech CG8, Purolite C100E). ResinTech's highly crosslinked CNS10 only behind a chlorine feed.
Match
Fleck 5600SXT Parts and Pentair Part Numbers
Fleck 5600SXT parts by Pentair number: seal kit 60125, bypass 60049, turbine meter 60626, injector 10913-x by tank size, per service manual 42684.
Match
Whirlpool WHES30 and WHES40 Parts and Error Codes
Whirlpool WHES30/WHES40 parts by number: seal kit 7129716, nozzle and venturi 7398705 (WHES40) or 7398674 (WHES30), brine valve 7381180, and what Err1 to Err5 mean.
Compare
Best whole house filter and softener combo, by spec
AFW Fleck 5600SXT 48K with upflow carbon: 48,000 grains, 12 gpm, 1.5 cu ft carbon. Aquasana SimplySoft 60K prints NSF/ANSI 44; Kind and SpringWell are salt-free.
Compare
Best water softener cleaner: Res Care vs Iron OUT
ResCare vs Iron OUT vs Rust OUT: what each SDS lists, the label dose per cubic foot or per 40 lb of salt, who claims NSF/ANSI 60, and who should skip each one.
Compare
Best water softener for city water, by spec
AFWFilters Fleck 5600SXT 48K: 1.5 cu ft of 10% crosslink resin, 6.5 gpm, 5-year valve and 10-year tank warranty. Six in-stock Amazon units compared on maker figures.
Compare
Best portable RV water softener, by grain capacity
On The Go OTG4-VM-DBLSOFT and Glacier Fresh at 16,000 grains cover most hookups; divide grains by hardness in gpg for gallons between regenerations.
Compare
Best water softener salt: pellets vs crystals vs KCl
Pellets with an anti-bridging additive at 99.65% to 99.8% published purity are the default; potassium chloride needs 10 to 15% more product per regeneration.
Compare
Best water softener for well water, by spec
AFWFilters Iron Pro 2 64K: the only Amazon-sold softener with a printed iron ceiling, 6 ppm, 2 cu ft fine mesh resin, 10 gpm. Above 5 ppm an iron filter goes first.
Refrigerator filters 22 pages
Diagnose
Generic vs OEM Fridge Filter: Check the NSF Listing
Neither OEM nor generic is certified by default. Look the model up at NSF, WQA or IAPMO: genuine EPTWFU01 is IAPMO-certified to 42, 53, 401; some generics 42 only.
Diagnose
Refrigerator Water Filter by Model Number
GE publishes no model-to-filter table. Read the old cartridge code, find the model number label, and route to the right cartridge across 6 brand families.
Match
LG LT600P Water Filter: Part Numbers and Cross-Fits
LG LT600P (5231JA2006A / 5231JA2006F) is rated 300 gallons or 6 months; NSF lists it at 0.5 gpm to NSF/ANSI 42 and 53, with lead and cyst reduction.
Match
GE GSWF Water Filter: Fit, Interval, NSF Cross-Fits
GE GSWF twist-and-lock cartridge: GE says 6 months, prints both 300 and 750 gallons, and has stopped making it. Which cross-fits NSF lists to 42, 53 and 401.
Match
Frigidaire EPTWFU01 Filter: Specs and Cross-Fits
Frigidaire EPTWFU01 PureSource Ultra II: 125 gal, 0.65 gpm, 6 months, IAPMO R&T certified to NSF/ANSI 42, 53 and 401. NSF-listed cross-fits are 200 gal at 0.5 gpm.
Match
Whirlpool EDR2RXD1 everydrop Filter 2: Fit and Specs
everydrop Filter 2 EDR2RXD1: 200 gallons or 6 months, NSF/ANSI 42, 53 and 401, 70 contaminants including 99% of microplastics, per Whirlpool's own product page.
Match
Samsung DA29-00003G Filter: Fit and Cross-Fits
DA29-00003G is Samsung's HAFIN1/EXP cartridge for head DA97-06317A, not the 300-gallon HAF-CIN DA29-00020B; the ICEPURE cross-fit lists NSF/ANSI 42.
Match
LG LT800P Water Filter: Part Numbers and Cross-Fits
LG LT800P (ADQ73613401, ADQ73613408) is rated 200 gallons or 6 months, NSF/ANSI 42 and 53 per LG's page; ICEPURE's cross-fit lists 42 and 372, not 53.
Match
Frigidaire WF3CB Replacement: Fit and Cross-Fits
Frigidaire WF3CB is the PureSource3 cartridge. Its NSF-listed cross-fits are rated 300 gal at 0.5 gpm to NSF/ANSI 42; the EPTWFU01 is a different 200 gal element.
Match
Whirlpool EDR4RXD1 Water Filter: Fit and Cross-Fits
Whirlpool EDR4RXD1 (EveryDrop Filter 4) replaces Maytag UKF8001 and 4396395 per cross-fit makers, rated 300 gallons or 6 months, NSF/ANSI 42 and 372.
Match
Samsung HAF-QIN/EXP Filter: DA97-17376B Fit, Interval
Samsung lists HAF-QIN/EXP as cartridge DA97-17376B for system DA97-08006C, rated 300 gallons or 6 months, NSF/ANSI 42 and 53 (no 401 on Samsung's page).
Match
Whirlpool EDR3RXD1 Water Filter: Fit and Cross-Fits
Whirlpool EDR3RXD1 (EveryDrop Filter 3) replaces P1WB2 and, per cross-fit makers, 4396841: 200 gallons or 6 months, 73 contaminants per Whirlpool.
Match
Kenmore 9081 Water Filter: EveryDrop Cross-Reference
Kenmore 46-9081 is EveryDrop Filter 1 (EDR1RXD1), 46-9083 is Filter 3 (EDR3RXD1), 200 gallons or 6 months each; 46-9930 lists under Filter 1.
Match
GE XWF vs XWFE Water Filter: Fit, Chip, Cross-Fits
GE XWFE replaces the XWF and fits any GE fridge that names either; GE says 6 months, no gallon figure. Which cross-fits carry the chip.
Match
GE MWF Water Filter: Fit, Cross-Fits, NSF Listing
GE MWF twist-in cartridge: which GE and Hotpoint fridges take it, and which cross-fits NSF lists to 42, 53 and 401 at 300 gallons and 0.5 gpm.
Match
Frigidaire ULTRAWF Filter: Fit, Cross-Fits, WF3CB
Frigidaire ULTRAWF fits the PureSource Ultra push-twist housing. Cross-fits list NSF/ANSI 42 at 300 gal, 0.5 gpm. Not a WF3CB or EPTWFU01 fit.
Match
Whirlpool EDR1RXD1 Water Filter: Fit and Cross-Fits
Whirlpool EDR1RXD1 (EveryDrop Filter 1) replaces W10295370A: 200 gallons or 6 months, NSF/ANSI 42, 53 and 401 per Whirlpool, and the cross-fits.
Match
Samsung DA29-00020B Filter: Fit and Cross-Fits
Samsung rates the DA29-00020B (HAF-CIN/EXP) at 300 gallons or 6 months and lists it to NSF/ANSI 42 and 53; fits RF22 to RF28 French-door models.
Match
LG LT700P Water Filter: Part Numbers and Cross-Fits
LG LT700P (ADQ36006101) is rated 200 gallons or 6 months, NSF/ANSI 42 and 53 per LG's page, and does not fit an LT1000P (ADQ74793501) housing.
Match
LG LT1000P Water Filter: Fit, Interval, Cross-Fits
LG LT1000P (ADQ74793501) is rated 200 gallons or 6 months and listed to NSF/ANSI 42, 53 and 401 by LG. It does not fit LT700P refrigerators.
Match
GE RPWFE Water Filter: Fit, Chip, Cross-Fits
GE RPWFE: 170 gallons or 6 months, NSF/ANSI 42 and 53 per GE's data sheet, plus the RFID chip the RPWF lacks. Which cross-fits carry a chip.
Compare
Best refrigerator water filter, by listing row
Genuine cartridges by maker document and certifier row: Frigidaire EPTWFU01 IAPMO R&T 42, 53, 401 at 125 gal; everydrop EDR1RXD1 NSF 200 gal; GE XWFE 170 gal.
Filters and cartridges 18 pages
Diagnose
Why is my tap water cloudy white? The glass test
Milky water that clears bottom-up in about 1 minute is dissolved air. Water that stays cloudy is turbidity; EPA caps public systems at 1 NTU.
Diagnose
Black specks after a new carbon filter: flush or test
Black specks after a filter change are carbon fines: GE says flush 2 to 3 gallons. Specks that outlast the flush point to manganese at 0.05 mg/L or rubber.
Diagnose
NSF/ANSI 42, 53, 58, 401, 55, 44, 177, 372 and P473
NSF/ANSI 42 is taste, 53 is health contaminants, 58 is RO at 75% TDS reduction, 55 is UV at 40 mJ/cm², and P473 is withdrawn into 53 and 58.
Size
Water filter life calculator: gallons and days
Days = rated gallons / gallons per day, capped by the maker's months. A 40-gallon, 2-month Brita Standard at 0.5 gal/day lasts 60 days, not 80.
Size
Micron rating picker: which sediment filter micron
Coarse to fine: a 700 to 15 micron screen, then a 5 micron cartridge (NDSU: 10 to 15 micron for a drilled well, 2 for a dug well), absolute 1 micron for cysts.
Match
Shower Filter Replacement Cartridge by Model
Aquasana AQ-4100/4105 take AQ-4125 (10,000 gal or 6 months), Culligan WSH-C125 takes WHR-140, Sprite HO2 takes HOC (25,000 gal), SL2 takes SLC, SF100 takes SFC100.
Match
ZeroWater Filter Compatibility and When to Change
One ZR-017 filter fits every legacy ZeroWater pitcher; the 2025 Culligan ZeroWater line takes ZEROF01. Both makers say replace at a TDS reading of 006.
Match
PUR Pitcher Filter Compatibility: PPF951K vs PPF900Z
PUR Plus PPF951K (99.7% lead reduction at pH 6.5) and plain PPF900Z fit the same 14 PUR pitchers, replaced every 2 months or 40 gallons per PUR.
Match
Aquasana AQ-5300 Replacement Filters by Model
Aquasana AQ-5300 takes AQ-C3-R (600 gal), AQ-5300+ takes AQ-C3M-R (800 gal), AQ-5200 takes AQ-C2-R (500 gal), Direct Connect AQ-MF-1-R (784 gal), all 6 months.
Match
GE Whole House Water Filter Replacement by Housing
GE GXWH40L and GXWH35F take the 10 x 4.5 in FXHSC or FXHTC every 3 months; GXWH04F shares the WS03X10038 O-ring. Which FX cartridge fits which housing.
Match
Culligan HF-360 and WH-HD200-C Replacement Filters
The Culligan HF-360 takes 10 x 2.5 in cartridges (CW-MF, CW-F, P5); the WH-HD200-C takes 10 x 4.5 in (R50-BBSA, CW5-BBS, RFC-BBSA), 8,000 to 24,000 gallons each.
Match
20 Inch Big Blue Cartridge Compatibility
Every 20 in Big Blue housing takes a 20 x 4.5 in cartridge: Pentek DGD at 4.50 in, EP-20BB at 4.63 in, 1 to 25 micron. Carbon block runs fatter than sediment media.
Match
10 Inch Water Filter Cartridge Compatibility
A standard 10 in housing takes any 10 x 2.5 in DOE cartridge: Pentek P5 sediment at 2.38 x 9.88 in, CBC-10 carbon block at 2.88 x 9.75 in, on a #237 O-ring.
Match
iSpring WGB32B Replacement Filters and Cross-Fits
The iSpring WGB32B takes one FP25B and two FC25B 20 x 4.5 in cartridges, changed every 6-12 months or 100,000 gallons. Pentek DGD and EP-20BB cross-fit.
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Express Water WH300SCKS Replacement Filters
Express Water WH300SCKS takes FLTWH2045S1, FLTWH2045K and FLTWH2045C1 (set FLTWH2045CKS1), 4.5 x 20 in, changed every 6-12 months or 100,000 gallons.
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Best gravity water filter: Berkey alternatives
LifeStraw Home states NSF/ANSI 42, 53, 401 and a 264 gal membrane; Waterdrop King Tank states 42, 372 and 6,000 gal carbon. No listing confirmed.
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Best RV water filter: inline vs canister, by spec
No RV inline filter page read lists NSF/ANSI 53. The one maker with published figures rates 5 micron nominal, 1 to 4 months, on a 3/4 in hose thread.
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Best whole-house sediment filter for well water
Coarse sand: a Rusco spin-down, 1 to 25 GPM, screens 700 to 15 micron. Fine silt: a Pentek 150233 Big Blue at 1 psi @ 15 gpm with a 5 micron nominal cartridge.
City water 13 pages
Diagnose
Wildfire water advisory: do not drink, do not boil
EPA says boiling wildfire-impacted water could create an inhalation risk until VOCs are ruled out. Benzene's federal MCL is 0.005 mg/L. Read the notice type first.
Diagnose
How to read your Consumer Confidence Report
A CCR is due by July 1 and covers mandatory monitoring only. The lead line is a 90th percentile of up to 100 homes, and data can be 5 years old.
Diagnose
Boil water notice: what boiling does not fix
CDC says 1 minute at a rolling boil, 3 above 6,500 feet. Boiling handles microbes and does nothing for lead, nitrate or PFAS. Here is the full procedure.
Diagnose
Chlorine or chloramine in city water: which carbon
EPA gives chlorine and chloramine the same 4.0 mg/L limit; only removal differs. Read the CCR, run a free-and-total strip, then pick the carbon.
Match
Brita Faucet Filter Replacement: FR-200 Fit Guide
Every Brita faucet mount (FF-100/SAFF-100, Elite or Elite Advanced) takes the FR-200: 100 gallons, 0.58 gpm, WQA-certified to NSF/ANSI 42, 53 and 401.
Match
PUR Faucet Filter Replacement: RF9999 vs RF3375
PUR's sheet gives RF9999 and RF3375 one rating: 100 gallons, 0.52 gpm, NSF/ANSI 42, 53 and 401, and one fit list of 24 mounts from FM2500V to PFM400H.
Match
Waterdrop 10UA, 15UA, 10UB Replacement Filters
Waterdrop 10UA and 10UB take the WD-RF10 (11,000 gallons or 12 months); the 15UA takes the WD-RF15 (19,000 gallons or 24 months). UF housings differ.
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Aquasana Rhino EQ-1000 Replacement Filters
The Aquasana Rhino EQ-1000 takes an EQ-304 pre-filter every 2 months, an EQ-PFC.35 post-filter every 6 months and an EQ-1000R tank at 1,000,000 gallons or 10 years.
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Best whole house water filter for PFAS, by spec
A.O. Smith HomeShield AOS-HS-1200 is the only whole-house unit found with NSF/ANSI 53 PFAS certification: below 4 ng/L for 500,000 gal at 5.7 gpm.
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Best faucet mount water filter: lead, PFAS, by spec
PUR PLUS RF9999: NSF/ANSI 42, 53 and 401 listed, 99.92% Total PFAS, 100 gallons, 0.52 gpm. ZeroWater ExtremeLife: 400 gallons, PFOA/PFOS only, no lead line.
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Best whole-house water filter for city water
Chlorinated city water: Pentair Pelican PC600 (NSF/ANSI 42 and 61, 662,400 gal, 8 gpm) or Aquasana EQ-1000 (1,000,000 gal). Over 8 GPM: iSpring WGB32B, 15 GPM.
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Best under sink water filter without RO, by spec
CuZn UC-200: 50,000 gallons or 5 years, NSF/ANSI 42 and 372 listed. Aquasana Claryum Max Flow: NSF/ANSI 42, 53 and 401, 99.7% PFOA/PFOS, 800 gallons.
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Best shower filter: who can prove NSF/ANSI 177?
NSF/ANSI 177 covers free chlorine only. No brand here is in NSF's listing. Sprite's own sheet names the standard; Culligan names only a certifier.
Reverse osmosis 9 pages
Diagnose
Reverse osmosis Black Friday and Prime Day deal check
Black Friday is November 27, 2026. Before buying RO on sale, check GPD at your pressure (APEC: 50 GPD at 60 psi, 30 at 50), drain ratio and NSF/ANSI 58.
Diagnose
Reverse osmosis water tastes bad: 5 causes by taste
Flat RO water is normal: NSF/ANSI 58 requires 75% TDS removal. Salty means the membrane, rotten egg means sanitize, chlorine the post-filter.
Diagnose
Reverse osmosis tank not filling: causes and fixes
RO tanks stop filling below iSpring's 45 psi feed minimum or with precharge under 5 to 10 psi empty. Six causes, the gauge check for each, the fix.
Size
Reverse osmosis GPD and tank size calculator
Effective GPD = rated GPD x (psi / 60) x (1 + 0.015 x (F - 77)). A 75 GPD unit at 50 psi, 60 F makes about 47 GPD from a 3.2 gal tank. Calculator.
Match
DREO Reverse Osmosis Replacement Filters by Model
DREO RO Water Filter 112 takes one 265 gallon combo cartridge; the 511 takes DR-KPA018 (about 1,050 gallons) or DR-KPA017 plus the 6 month DR-KPA016.
Match
Bluevua RO100ROPOT Replacement Filters by Stage
Bluevua RO100ROPOT and RO100ROPOT-UV take the same PP, CTO, RO and PCF filters: 12 months for PP, CTO and PCF, 12-24 months for the RO membrane.
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Best under-sink reverse osmosis system, by spec
Tankless: Waterdrop G3P800, 800 GPD, 3:1 pure to drain, NSF/ANSI 58 and 372. Tanked: iSpring RCC7AK, 75 GPD, NSF/ANSI 58, alkaline stage. Yearly filter cost.
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Best tankless reverse osmosis system, by spec
Waterdrop X12 leads at 1,200 GPD and 3:1 pure to drain, NSF/ANSI 58 and 372 listed. Waterdrop G3P600 is the right-sized pick at 600 GPD and 2:1.
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Best countertop reverse osmosis system, by spec
Waterdrop M6SL is the pick: NSF/ANSI 58 and 372 on its page, 75 GPD, 3:1 pure to drain, $69.99 filter per 1,100 gallons. Six units on published spec.
Whole-house systems 4 pages
Diagnose
Whole house filter and softener install order
Well: tank, sediment, iron fix, softener, carbon, UV last, since Viqua caps UV inlet at 7 gpg and 0.3 mg/L iron. City: sediment, carbon, softener.
Diagnose
Low water pressure after whole house filter: 4 causes
A 20 x 4.5 in Big Blue housing drops 1 psi at 15 gpm with 1 in ports and 2 psi with 3/4 in ports per Pentair. A gauge on each side finds the cause.
Size
Whole-house filter flow rate calculator: GPM
Peak gpm = showers running at once x 2.5 + one faucet at 2.2, or WQA fixture units x 0.4 + 2. A 2-bath home pulls about 7 gpm; a 20 x 4.5 in housing is rated to 15.
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Best 20 inch Big Blue filter housing, by spec
Pentek 150233: 1 in NPT, 90 psi max, NSF/ANSI 42 listed housing. iSpring WGB32B if you want a full 15 GPM system with wrench and bracket in the box.