Meter box lidMetal or plastic, and it may be marked Water Meter.
Register lid (hinged cover)Flip it up to read the dial, then close it again.
RegisterPermanently sealed unit that counts and shows the water used.
Sweep handOne full turn is commonly 10 gallons or 10 cubic feet.
Odometer (number wheels)Rolling digits that show the running total, like a car's mileage.
Low-flow indicator (leak indicator)Turns at the smallest flow. Moving with faucets off means a leak.
Meter housing (main case)The bronze, brass or plastic shell that everything else fits into.
Curb stop (shut-off valve)Shuts off the water service line to the whole property.
Meter in its box 15
Meter boxA box in the ground near the curb that houses the meter.
InletWater enters here from the street side.
OutletMeasured water leaves here for the house.
Service lineThe pipe that carries water from the street to the property.
Coupling nutThreads onto the meter's spud end. A gasket inside it seals.
TailpieceIts far end carries a pipe thread for the service line.
Bottom plateA cast iron, bronze or plastic plate that closes the housing's underside.
StrainerCatches grit before it can jam the measuring element.
Measuring chamberTraps and empties a fixed amount of water with every cycle.
Nutating discWater pushes it into a wobble, called nutation, on its ball.
Gear trainReduces the disc's many wobbles to gallons or cubic feet.
Drive magnetPasses the disc's motion up to the magnet inside the register.
Follower magnetFollows the drive magnet and turns the register's gear train.
Disc spindleThe meter counts cycles by tracking this pin's movement.
Seal screw (tamper screw)Guards against anyone removing the register without authority.
Register face close-up 1
Fixed zeroA printed 0 that never turns. The sweep hand supplies that digit.
How this list was compiled: Part names and every detail line were checked, for facts only and with nothing copied, against pages read on 2026-09-20. Wikipedia: https://en.wikipedia.org/wiki/Water_metering (displacement or PD meters, nutating disk and oscillating piston types; the piston or disk moves a magnet driving the register; built-in strainer; bronze, brass or plastic bodies; magnetic coupling of a magnet in the measuring chamber and one at the bottom of the register; gears, sweep hand and odometer-style wheels; the leak detector geared closer to the speed of the drive magnet; one turn of the sweep hand, the fixed zero and the worked reading 1,234,567 gallons; AWWA C700 as the standard for displacement meters with a bronze main case); https://en.wikipedia.org/wiki/Positive_displacement_meter (in a nutating disc flow meter a round disc sits on a spindle in a cylindrical chamber, and the meter tracks the movements of the spindle; a disk on a sphere is wobbled by the flow and each rotation is a finite amount of fluid); https://en.wikipedia.org/wiki/Curb_box (the shut-off valve of a property's water service line, called a curb cock or curb stop). A regional water utility association's guide: https://www.smarthomewaterguide.org/how-to-read-your-water-meter (the meter sits near the curb or sidewalk in a concrete box with a metal or plastic lid that may be marked Water Meter; a small hinged cover over the face; the large sweep hand, one complete rotation being 10 gallons or 10 cubic feet; the low-flow indicator that looks like a small triangle, star or gear; the static zero; the leak check with no water in use; 1 cubic foot is 7.48 gallons). A maker of nutating disc meters, product data sheet and installation manual, found from https://www.badgermeter.com/products/meters/nutating-disc/disc-series-meters/: https://badgermeter.widen.net/content/hrap6cogzl/original?download=false&x.app=api (operation: strainer, measuring chamber, disc nutating on its own ball, drive magnet, follower magnet inside the permanently sealed register, register gear train; three basic components: meter housing, measuring chamber and register; materials table naming housing bottom plates, disc, strainer, disc spindle, magnet, register lid and shroud; tamper-resistant seal screw; tailpieces, coupling nut and spud thread) and https://badgermeter.widen.net/content/n77fwluqdl/original?download=false&x.app=api (flow arrow on the meter housing, meter box, service line, curb (shutoff) valve opened to pressurize the meter's service line, inlet-side and outlet-side valves, coupling nuts on the threaded spud ends with a connection gasket inside each nut). A maker of oscillating piston meters, parts list and odometer guide, found from https://www.zennerusa.com/residentialmeters: https://www.zennerusa.com/_files/ugd/64e808_12f86c4fc8824c75baf8981da5d975e9.pdf (register cover, register shroud, register, tamper screw, housing, chamber assembly, strainer, bottom plate gasket, bottom plate in brass, cast iron or plastic) and https://www.zennerusa.com/_files/ugd/64e808_ca1d7e20d7b4403f8b06785d1db715b9.pdf (a residential gallon odometer is six wheels and a fixed zero; registers in cubic feet, cubic meters or US gallons). No maker is named on the page. Re-checked on 2026-09-30: all 24 names found again in two or more independent sources: Wikipedia's wikitext for Water metering, Positive displacement meter and Curb box; the water utility association's guide; the first maker's data sheet and manual and the second maker's parts list (all at the addresses above, fetched again); and two sources new today. US Naval Facilities Engineering Command, Utilities Metering, NAVFAC MO-221 (1988, approved for public release), https://archive.org/details/manualzilla-id-5930820 (oscillating piston and nutating disk meters; a magnetic assembly in the measuring chamber drives a follower magnet, which drives the register geartrain; coupling nuts and coupling tailpiece; meter casing, strainer, meter box), which gives the coupling nut, the tailpiece and the follower magnet a second source beside the first maker. A US Office of Education plumbing curriculum, https://archive.org/details/ERIC_ED216201 (a meter installed in the ground: the meter box lid must be unlocked to read it), which with the utility guide supports the meter box lid. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; own work, nothing traced or copied. Licence: own work
How it works
The parts of a water meter fall into two sets: the box, pipe and case you can see, and the works that measure and show the water. This drawing cuts one home meter open in its box and enlarges the register face beside it.
Read the full guide
Parts of a water meter and their functions, in flow order
Water comes along the service line, passes the curb stop and enters at the inlet. The strainer catches grit. In the measuring chamber the water pushes the nutating disc into a wobble, and every cycle passes a fixed amount. The drive magnet hands that motion to the follower magnet inside the sealed register, where the gear train turns the sweep hand and the odometer.
Leak indicator or sweep hand?
The sweep hand is the long thin arm. The low-flow indicator is the small triangle, star or gear, and it is geared to turn at flows too small to move the hand. Watch it with every faucet off.
Pick the group Register face close-up for the 4 dial parts alone: sweep hand, odometer, low-flow indicator and fixed zero. The drawing zooms in.
Start here: 8 main parts covers what you can see from above with the box lid off, from the register lid to the curb stop.
Questions and answers
What is the little triangle on my water meter?
It is the low-flow indicator, also called the leak indicator, part 7. It turns at flows too small to move the sweep hand. If it moves while every faucet and appliance is off, water is leaking somewhere past the meter.
How do you read a water meter?
Read the odometer wheels from left to right. Where the last digit is a fixed zero, put the number under the sweep hand in its place. Wheels showing 045273, a fixed zero and the hand on 6 read 452,736 gallons.
What is inside a water meter?
A home positive displacement meter holds a strainer, a measuring chamber with a nutating disc or an oscillating piston, and a drive magnet. The sealed register above holds the follower magnet, the gear train and the dial.
How many gallons is a cubic foot on a water meter?
One cubic foot is 7.48 gallons. Registers are made in gallons, cubic feet or cubic meters, so check which unit your dial shows before you compare it with a bill.