Plumbing
Home plumbing: diagnose a leak, a freeze risk or a noise, size a heat cable or a pressure tank, match a model number to its part, and compare the gear worth a shortlist.
Every page under this heading is about the pipes, the fittings and the equipment they feed: what a symptom means, what size of part it takes, which component fits the model you already own, and which gear is worth a shortlist. Codes and standards are cited by number.
Plumbing calculators: inputs you already have, one formula, one answer, with the formula printed so the number can be checked.
11 calculators
Diagnostic plumbing guides: a symptom or a risk in, a fix or a part class out, with the code or standard cited by number.
28 guides
Plumbing parts: a model number in, the part that fits it out, with the cross-fit alternatives and the spec sheet that says so.
14 parts
Plumbing gear compared on published specification: what each unit is rated for, what it is not, and which one a given house needs.
29 reviews
Water heaters 26 pages
Diagnose
Water heater blanket: worth it? DOE's 7% to 16%
DOE's 2017 guide: a tank warm to the touch can save 7% to 16% with a blanket, pipe wrap 3% to 4% more. A. O. Smith and an electric manual say newer tanks need none.
Diagnose
How to flush a tankless water heater by maker
Rinnai: 4 gallons of white vinegar for 1 hour. Rheem: no more than 2 gallons, 45 minutes. Noritz: 3-4 gallons, 1 hour. Navien: 45 minutes. Takagi prints none.
Diagnose
Water heater temperature: 120 or 140 F, and why
CPSC urges 120 F and prints 140 F as a 6-second burn; DOE puts the saving at 4% to 22% a year. Dishwashers without a booster are the exception, with a mixing valve.
Diagnose
Water heater leaking: where it comes from and fix
Five places a tank water heater leaks, from the T&P pipe to the tank itself. Makers say drips at the T&P pipe mean pressure over 80 psi; a tank leak means replace.
Diagnose
Water heater age from serial number: by brand
Rheem reads month then year (1209 = Dec 2009); A.O. Smith International and Lochinvar read year then week (2037 = week 37 of 2020); Bradford White uses letters.
Diagnose
Water heater pilot won't stay lit: thermocouple test
Bradford White's service manual: 10 millivolts closed-circuit keeps a thermocouple, 350 to 850 mV is a normal thermopile, two LED flashes is a weak pilot.
Diagnose
Water heater no hot water: electric and gas causes
Rheem lists 8 electric and 3 gas causes of no hot water. Upper element and ECO kill all of it; a lower element only shortens it. Press the reset once, never twice.
Diagnose
Water heater T&P valve dripping: causes and fix
A T&P relief valve opens at 150 psi or 210 F. A drip after each heating cycle is usually thermal expansion or supply pressure over 80 psi, not a bad valve.
Diagnose
Hot water takes too long: recirculation options
The wait is the cold water in the pipe: Type L copper holds 0.0251 gal per foot at 3/4 inch. Which of four recirculation options fits, and who should just insulate.
Diagnose
Water heater noises: popping, clicking, rumbling
Popping and rumbling are steam trapped under sediment: flush once a year, every 6 months on hard water (Rheem). Ticking or clicking is heat traps or pipe expansion.
Size
Water heater recovery time calculator
Recovery GPH = input x efficiency / (8.33 x temperature rise). A 4,500 W element at a 90 F rise gives 20.5 GPH, so a 40-gallon tank reheats in about 117 minutes.
Size
Water heater element ohms calculator and test
R = V² / P: a 4500 W, 240 V element computes to 12.8 ohms. The maker's manual passes 5 to 25 ohms; OL, under 5 or over 25 means replace. Breaker off first.
Size
Tankless water heater descale interval by hardness
Navien, Rinnai and Rheem all cap hardness at 200 mg/L. Navien and Rinnai band flushing by hardness; Rheem says flush annually.
Size
Hot water wait time calculator by pipe length
Seconds to hot water = pipe length x gallons per foot / gpm x 60. 50 ft of 3/4 in Type L copper holds 1.26 gallons: 30 seconds at a 2.5 gpm shower, 38 at 2.0 gpm.
Size
Water heater size calculator: first hour rating
Count each hot-water use in the busiest hour, multiply by DOE's gallons per use, add them up. DOE's own example is 66 gallons; buy a first hour rating of 66 or more.
Size
Tankless water heater size: GPM and temperature rise
Add the gpm of fixtures running at once, subtract incoming from outlet temperature: BTU/h = GPM x 500 x rise, kW = GPM x rise / 6.83. 4.7 gpm at 73 F is 50.2 kW.
Size
Expansion tank size calculator: gallons and psi
Tank gal = heater gal x expansion factor x (max psi + 14.7) / (max psi - line psi). A 50 gal heater at 140 F on 60 psi needs 1.4 gal: an Amtrol ST-5 or Watts PLT-5.
Match
Water Heater Thermocouple or Thermopile: By Type
Standing-pilot tanks take a 30 mV Honeywell CQ100A thermocouple, 18 to 36 in. Status-light tanks run a 750 mV thermopile; FVIR makers sell the pilot as one assembly.
Match
Water Heater Element by Wattage and Voltage
Match the rating plate: same voltage, no greater wattage (A.O. Smith). Camco screw-in elements: 1 in NPS thread, 1-1/2 in hex; 4500 W at 240 V is ProLine standard.
Match
Thermal Expansion Tank Cross-Reference by Model
Amtrol ST-5, Watts PLT-5, Zurn XT-8 and TW 5-1 fill the 2-gallon slot; ST-12, PLT-12, XT-18 and TW 12-1 the 4.5. All 3/4 in NPT, 150 psi, precharge 20 to 50 psi.
Match
Water Heater Anode Rod by Model: Thread and Size
Residential anode rods are 3/4 inch NPT with a 1-1/16 inch hex head. Rheem publishes 42, 44, 54 and 58 inch rods; Bradford White cuts segmented rods to length.
Compare
Best thermal expansion tank, by maker spec sheet
Amtrol ST-5 for a 40 to 50 gal heater (2.0 gal, 50 psig precharge, 7-year warranty), ST-12 for 60 to 80 gal, Watts PLT-12 when IAPMO and NSF 61 must be printed.
Compare
Best gas tankless water heater, by maker spec sheet
Maker sheets compared: Rinnai RX199iN 199,000 BTU, UEF 0.98, PVC vent, ENERGY STAR; Rheem RTG-70XLN 160,000 BTU, UEF 0.82, outdoor; Rinnai V53DeN 120,000 BTU budget.
Compare
Best point-of-use mini-tank water heater, by spec
Maker sheets compared: Stiebel Eltron SHC 2.5/4/6 at 1300 W, 11.3 A on a 120 V outlet, EcoSmart ECO MINI at 1440 W, Bosch at 6.8 GPH, and who needs a pump instead.
Compare
Best electric tankless water heater, by breaker line
Stiebel's Tempra 24 prints 2 x 50 A breakers, 2 x 8/2 AWG, 150 A service and a 54 F rise at 3.0 gpm; a 27 kW unit is 112.5 A on 3 x 40 A and 200 A service.
Compare
Best hot water recirculation pump, by maker spec
Watts' 500800 manual prints 120 VAC, a 15-minute timer, a 140 F maximum and not for tankless; Taco's Hot-LinkPlus-e prints 44 W max. Who should skip both.
Toilets, faucets and showers 23 pages
Diagnose
Shower head and faucet Black Friday deal check
Federal caps are 2.5 gpm for shower heads and 2.2 gpm for faucets; California prints 1.8. Check the cap, the cartridge family and the hole count before the sale.
Diagnose
Bidet Black Friday and Prime Day deal check
Black Friday is November 27, 2026. Before buying a bidet seat on sale: a GFCI outlet inside a 39 to 48 in cord, the right bowl, a 403 or 1273 W heater.
Diagnose
Will a bidet fit my toilet? 5 checks before buying
Bolt spread 5.5 in, round or elongated bowl, a reachable fill valve for the 7/8 in T-valve, a flexible supply hose, and a GFCI outlet within a 3.9 to 4 ft cord.
Diagnose
Which faucet cartridge do I have? Brand and clip
Find the brand first, then the retainer: Moen 1225 under a copper clip, 1255 under a nut, Delta RP50587 under a bonnet nut. Then take the old one with you.
Diagnose
Running toilet: the dye test that names the part
EPA's dye test: food coloring in the tank, color in the bowl after 10 minutes means the flapper. A running toilet wastes about 200 gallons a day.
Size
Shower water and energy cost calculator by gpm
Gallons = gpm x minutes; Btu = hot gallons x 8.34 x rise / UEF. An 8 minute 2.5 gpm shower is 20 gallons and 2.42 kWh electric; 1.5 gpm cuts both by 40 percent.
Match
Kohler Rite-Temp Cartridge: GP800820 vs GP77759
Kohler's parts pages: GP800820 is the cartridge for K-304 and K-11748, GP77759 is only the mixer cap, GP800881 fits K-8304. Ask about Kohler's warranty first.
Match
Toilet Rough-In: Measure 10, 12 or 14 in, by Model
Rough-in is finished wall to the centre of the closet bolts (TOTO), near 10, 12 or 14 in; 12 in is standard. Model numbers by rough-in from maker spec sheets.
Match
Toilet Seat Size: Round vs Elongated, Measured
Measure two things: 5 1/2 inches between bolt-hole centres, then midpoint to front rim. About 16 1/2 inches is round, about 18 1/2 inches is elongated (Bemis).
Match
Delta Cartridge by Model: RP46074 vs RP19804
Delta's parts pages: RP46074 for MultiChoice 13/14 after March 2006, RP19804 before, RP32104 for Monitor 17, RP50587 for DST sinks. Delta may ship it free.
Match
Toilet Fill Valve by Model: 400H, 400A, Korky 528
Match a fill valve to the overflow tube, not the brand: Fluidmaster 400H adjusts 9 to 14 inches, Korky 528MP 8-1/2 to 14, water 1/2 inch below the overflow top.
Match
Toilet Flapper 2 Inch vs 3 Inch by Model
Measure the old flapper: 3 inches across means a 2-inch flapper, 4 inches means a 3-inch one. Kohler canister and American Standard Champion 4 tanks take a seal.
Match
Moen Cartridge 1225 vs 1222 vs 1200: Which Fits
Moen's support index: 1225 for pre-2009 single-handle faucets and Moentrol showers, 1222 for Posi-Temp, 1255 after 2009, 1224 for two-handle. Moen may ship it free.
Compare
Best upflush macerating toilet, by maker spec sheet
Maker sheets compared: Saniflo Saniplus 15 ft lift, 150 ft run, 1/2 HP; Sanibest Pro 25 ft, 1 HP grinder; Liberty Ascent II 25 ft; Sanicompact 9 ft, sink only.
Compare
Best shower head for low water pressure, by spec
No head adds pressure (2.5 gpm at 80 psi federal cap). Maker sheets compared: High Sierra Classic 1.25 gpm, Delta 52668-BL 1.75 gpm, Speakman 2.5 gpm.
Compare
Best toilet repair kit: fill valve and flapper kits
Maker pages compared: Fluidmaster 400H kits adjust 9 to 14 in, Korky 528MP kits 8-1/2 to 14 in; measure the old flapper, 3 in across means a 2 in flapper.
Compare
Best bathroom faucet: sink faucets by maker sheet
Maker sheets compared: Moen Genta LX 6702 1.2 gpm, 1255 cartridge; Delta Trinsic 559LF RP101762; Kohler Devonshire K-394-4. All under the 1.5 gpm WaterSense cap.
Compare
Best instant hot water dispenser: maker spec sheets
Maker sheets compared: InSinkErator HOT150 750 W, 2/3 gal, 160 to 210 F, 1 year; HOT250 same tank, 3 years in-home; Moen IH2300 1500 W, 140 to 190 F, 40 cups/hour.
Compare
Best toilet by MaP score, gpf, rough-in and height
MaP list and maker sheets compared: TOTO Drake and Entrada, Kohler Cimarron and Highline, Woodbridge T-0001 all print 1000 g; Champion 4 one-piece 800 g at 1.6 gpf.
Compare
Best shower head, by maker spec sheet and gpm
Maker sheets compared: Moen 26009 2.5 gpm rain and handheld combo, 60 in hose; Delta In2ition 75655 and Kohler Forte 1.75 gpm WaterSense; High Sierra 1.8 gpm.
Compare
Best kitchen faucet: pull-downs by maker spec sheet
Maker sheets compared: Moen Arbor 7594 1.5 gpm, 1255 cartridge, 68 in hose; Delta Essa 1.8 gpm, MagnaTite; Kohler Simplice 1.5 gpm. All under the 2.2 gpm cap.
Compare
Best toilet seat: hinge, material, warranty compared
Maker sheets compared: Mayfair Cassel wood, Easy-Clean and Stay-Tite; Kohler Brevia plastic Quiet-Close; TOTO SS124 top-mount. All print 5-1/2 in holes, 1 year.
Compare
Best bidet attachment and seat, by maker spec sheet
Maker sheets compared: LUXE NEO 120 needs no outlet, 18 months; TOTO C5 403 W tank heater, 1 year; Kohler E580 hybrid, 3 years; Bio Bidet BB-2000 1400 W, 3 years.
Drains and disposals 9 pages
Diagnose
Garbage disposal leaking from bottom: find it
Most bottom drips start at the flange, dishwasher inlet or discharge gasket and run down. InSinkErator's newspaper test finds which; a housing leak is a call.
Diagnose
Toilet clogged: plunger vs auger, in order
Close the supply valve first. Korky says a toilet plunger clears a clog in 1 to 2 plunges; if not, a 3 ft toilet auger with a boot. Several slow fixtures: a plumber.
Diagnose
Slow drain: what to try first, in order
One slow fixture is a local clog: stopper, cup plunger over 4 inches of water, 25 inch barbed strip, 1/4 inch auger, then the P-trap. Several at once: a plumber.
Diagnose
Garbage disposal humming, not spinning: reset it
InSinkErator's fix: switch off, 1/4 inch Allen wrench in the bottom socket until it turns freely, cool up to 20 minutes, then press the red reset button.
Match
InSinkErator Model Cross-Reference by Series
InSinkErator comparison chart: 11 current models by HP, grind stages, sound, cord and warranty, plus Quick Lock interchange, serial tag and reset button.
Compare
Best laundry sink drain pump, by maker spec sheet
Maker sheets compared: Liberty 404CV 38 GPM at 5 ft, 21 ft shut-off, 4.3 gal, cCSAus; Superior 92017 1,800 GPH at 10 ft, 6 gal; Liberty 405 34 ft shut-off, 180 F.
Compare
Best plunger for toilet and sink, by drain shape
Korky prints a 6 in beehive head (99-4) for round and oblong toilet outlets and a 5.5 in cup (94-4) for flat sink and tub drains. Drano: never plunge after its gel.
Compare
Best garbage disposal, by grind stages and warranty
InSinkErator's chart: Badger 5 at 1 grind stage and 5 years, Evolution 0.75HP at 3 stages and 9 years, Evolution 1.0HP at 4 stages and 10 years.
Compare
Best drain snake and auger, by cable and guard
Klein's 53016 drum auger prints a 0.25 in cable at 25 ft; its 53017 toilet auger a 0.5 in cable with a porcelain boot. DrainX says a drum snake may damage a toilet.
Leaks and shutoffs 7 pages
Diagnose
Sump pump not turning on: float switch or power?
Liberty, Zoeller and Wayne's troubleshooting tables: tripped GFCI, float pinned on the pit wall, piggyback plug, air lock (3/16 in vent hole), check valve backwards.
Diagnose
Washing machine hoses: replace every 3-5 years
IBHS says to replace washing machine supply hoses every 3 to 5 years and upgrade to braided stainless; 1 in 60 insured homes filed a water claim 2016-2020.
Size
Sump pump size calculator: GPH at head, not HP
Gallons per inch of rise is pi x radius squared / 231. An 18 in pit rising 10 in a minute needs 661 GPH at 15 ft of head; a 3/10 HP Zoeller 53 gives 1,140.
Compare
New homeowner gifts: leak sensors, alarms, test kits
Eight housewarming gifts, each for a month-one check: USFA alarms on every level, EPA radon test below the third floor, the 80 psi code limit, CDC well test.
Compare
Best smart water shutoff valve, by maker spec sheet
Maker pages compared: Moen Flo in-line on 3/4 to 1-1/4 in with flow sensing; Frizzlife LP365 in-line, no hub; YoLink bolt-on for ball valves; Flume monitors only.
Compare
Best sump pump and battery backup, by 10 ft GPH
Zoeller rates the M53 at 34 GPM at 10 ft of head; Basement Watchdog rates the CITS-50 backup at 1,850 GPH at 10 ft. Neither helps if the check valve sticks.
Compare
Smart leak detectors and insurance credits
Mercury publishes up to 4.6 percent off a homeowners premium for a qualifying leak device. Amica publishes a programme and no percentage at all.
Pipes and freezing 7 pages
Diagnose
Burst pipe: what to do in the first ten minutes
Main valve first, at the meter or where the line enters the house. Then power off if it is safe, faucets open, photos, and no open flame on a frozen pipe.
Diagnose
What actually prevents frozen pipes
State Farm paid over $628 million on more than 20,000 frozen-pipe claims from 2024 through June 2025. The fix is pressure relief, not warmth.
Size
Heat cable sizing calculator: length and circuit
Chemelex's formula is pipe length x spiral ratio, plus 4 ft per globe valve, 2 ft per support, 1 ft per power connection. Its own 50 ft example needs 78.0 ft.
Match
Pipe Insulation Size by Pipe Diameter
Foam sleeves fit the pipe's outside diameter. Copper Tube Handbook: 1/2 in copper is 0.625 in OD, 3/4 in is 0.875 in; PEX matches; 1/2 in iron pipe is 0.840 in.
Match
Frost-Free Sillcock Length by Wall Thickness
Woodford 17, 19, 27 and Prier C-144 ship in wall thicknesses from 4 to 24 inches in 2 inch steps; Sioux Chief stops at 12. Order by wall, not overall length.
Compare
Best outdoor faucet cover and frost-free sillcock
Woodford 17 and 19 print ASSE 1019 Type C, 125 psi and 4 to 24 in walls; Prier P-164 ships 4 to 24 in. Every sheet says remove the hose or the faucet may burst.
Compare
Best heat cable for pipes: self-regulating vs fixed
HEATIT's JHSF prints 3 W/ft, a 37 F on / 50 F off thermostat and overlap allowed; Frost King's 7 W/ft kits say never overwrap. Who should skip both.
Dehumidifiers 6 pages
Diagnose
Dehumidifier Black Friday deal check: 65 F rating
Black Friday is November 27, 2026. An old-test 70 pint label is 40 to 45 pints under the 2019 DOE test. Check IEF first.
Diagnose
Dehumidifier pints vs litres per day explained
US pints per day are tested at 65 F 60 % RH since 2019, UK/EU litres at 30 C 80 %, Japan litres at 27 C 60 % per 50/60 Hz. No source prints a conversion factor.
Size
Dehumidifier size calculator: pints/day by room
ENERGY STAR's chart: under 2,000 sq ft needs 20-30 pints/day moderately damp, 25-40 very damp, 30-50 wet; over 2,000 sq ft 30+, 40+, 50+, on the 65 F rating.
Compare
Best dehumidifier UK and EU: compressor or desiccant
Meaco prints 8.5 L/day at 20 C 60 % for the Arete One 20L and 7.5 L at 10 C for the DD8L Zambezi desiccant. Why three makers' 20 L labels are three tests.
Compare
Best dehumidifier in Japan: 50 Hz vs 60 Hz picks
Corona prints 16.0/18.0 L/day at 27 C 60 % for the CD-WH1826, Panasonic 10.5/12.5 L/day for the F-YEX120B hybrid. The big tatami number is the concrete one.
Compare
Best dehumidifier for basement, by 65 F rating
ENERGY STAR lists the Midea Cube MAD50PS1QWT-A at 49.67 pints/day and IEF 2.01; Midea prints 41 to 95 F and a 14 ft pump. Why hOmeLabs' 50 is an 80 F number.
Water pressure 4 pages
Diagnose
Water hammer: banging pipes and arrestors
A bang when water stops is water hammer, a pressure wave moving over 4,800 feet per second. The fix is an ASSE 1010 arrestor, AA size for a home fixture.
Diagnose
Do you need a thermal expansion tank?
IRC P2903.4.2 requires thermal expansion control where a check valve, backflow preventer or PRV closes the supply to a tank water heater. Open systems may not.
Diagnose
High water pressure: when 80 psi needs a PRV
Both model plumbing codes cap static pressure at 80 psi and require a pressure-reducing valve above it. A hose-bib gauge gives the number overnight.
Compare
Best water pressure regulator (PRV) and gauge
Watts LF25AUB-Z3, Watts LFN45B, Zurn Wilkins NR3XL and 70XL and Resideo DS06 compared on adjustable range, factory setting, max inlet, bypass and ASSE 1003.