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USA Water Meter Sizing FAQ

Water Meter specifications in the USA are controlled by the American Water Works Association (AWWA). If  you are new to the waterworks or metering industry, meter and meter connection sizing can be confusing. Following is information to help you determine the correct size meter or couplings you have or may need. If you purchased a meter from a supplier outside the USA, it may be metric and ISO standards, and AWWA standard fittings and gaskets may not work properly.

Meter Connection Types

  • AWWA Meter Threads (male) - 1/2" - 2" meters
    • AWWA Meter threads are referred to by the size of the meter connection, not the actual measurement. Meter threads are straight threads, unlike pipe thread which is tapered. The sealing of a meter coupling nut and meter spud (threaded end of meter) is done by a compressed gasket as opposed to a pipe thread which is sealed by tapered threads and thread sealant.
    • Thread sealant should never be used on a water meter threads.
  • Female NPT Threads - 1-1/2" and 2" meters
  • Elliptical Flange (two bolt oval flange) - 1-1/2" and 2"
  • Round Flange - 2" and larger - Flange gaskets are the same as standards for flanged pipe.

Chart of Meter Size Characteristics:

Meter Size Common Name Flow Capacity Bore (I.D.) Approx O.D. of meter threads Lay Length
5/8" 5/8" x 1/2" 5/8" 1/2" 1.04" 7.5"
5/8" x 3/4" 5/8" x 3/4" 5/8" 3/4" 1.39 7.5"
3/4" x 7.5" 3/4" Short 3/4" 3/4" 1.39" 7.5"
3/4" 3/4" Full Size 3/4" 3/4" 1.39" 9"
1" 1" Meter 1" 1" 1.65" 10.75"
1-1/2" 1-1/2" Threaded (male) 1-1/2" 1-1/2" 2.38" 12-5/8"
2" 2" Threaded (male) 2" 2" 2.81" 15-1/4"
Flange end meter size Oval 2-bolt Flange
1-1/2" 1-1/2" Flange end 1-1/2" 1-1/2" 4" on center bolt holes  13"
2" 2" Flange end 2" 2" 4.5" on center bolt holes  17"

5/8" Water Meter (also referred to as 5/8" x 1/2")

A 5/8" water meter has a 5/8" water flow capacity. The bore of the meter is generally 5/8". a 5/8" meter does not have 5/8" threads. It has 1/2" AWWA Meter Threads and typically hooks up to a 1/2" or smaller water service line. A standard meter coupling for a 5/8" water meter has male NPT pipe threads on one end and a swivel meter coupling nut with 1/2" AWWA Meter Threads on the other. These use meter couplings and gaskets referred to interchangeably as 5/8" or 1/2". 5/8" meters are generally used on older homes where the service tubing size was 1/2"

5/8"  x 3/4" Water Meter 

A 5/8" x 3/4" water meter has a 5/8" water flow capacity just like a 5/8" meter. The bore of the meter is generally 5/8". a 5/8" x 3/4" meter has 3/4" AWWA Meter Threads and typically hooks up to a 3/4"  water service line or larger. A standard meter coupling for a 5/8" x 3/4" water meter has male NPT pipe threads on one end and a swivel meter coupling nut with 3/4" AWWA Meter Threads on the other. These use 3/4" meter couplings and gaskets.

We do have an adapter meter coupling available that has a meter nut thread for 3/4", but a 1/2" pipe thread on the nipple end.

IMPORTANT NOTE: Most manufacturers use the exact same meter internal and external register components for 5/8" x 1/2" and 5/8" x 3/4" meters, with the exception that 5/8" meter threads are milled down the smaller thread size. Therefore, either 5/8" x 1/2" or 5/8" x 3/4" may be marked with just 5/8" on the body and register which designated the internal capacity, not the thread size.

3/4" Water Meter (standard)

The standard 3/4" water meter has a lay length of 9" from then ends of the threaded spuds. It has a 3/4" measuring chamber capacity. The threads are 3/4" AWWA meter threads, the same size as for a 5/8" x 3/4" meter. These use 3/4" meter couplings and gaskets.

3/4" Short Water Meter

The 3/4" Short meter has a full 3/4" flow capacity, but has the shorter 7.5" lay length of the 5/8" x 3/4". It is most often used as a replacement for a 5/8" x 3/4" meter when a 5/8" x 3/4" was originally installed and a higher flow capacity is needed without changing the meter setter or coupling spread. These use 3/4" meter couplings and gaskets.

3/4" x 1" Meter

A 3/4" x 1" meter (aka 3/4" x 1" x 9" meter) is a 3/4" capacity water meter with 1" AWWA meter threads. It is commonly used to downsize where a 1" meter needs to be replaced with a 3/4" meter without changing meter couplings. However, the lay length is 9", the same as a standard 3/4" meter, therefore a 1-1/2" long adapter needs to be added for a standard 1" meter setter. This meter is fairly rare. These will use 1" meter couplings and gaskets.

1" Water Meter

The 1" water meter has a full 1" meter  flow capacity with 10-3/4" lay length. It has 1" AWWA Meter Threads (male). These use 1" meter couplings and gaskets.

1-1/4" Water Meter

These are mostly legacy meters and discontinued by most manufacturers. If you have one, it will likely be replaced by a 1' meter with a threaded bushing. We generally stock 1-1/4" meter gaskets for when these are repaired and replaced, and can special order bushings to downsize to 1" meters as replacements. If replacing, we recommend reducing any 1-1/4" pipe down to 1" with a pipe bushing or reducer coupling, and using 1" meter couplings.

1-1/2" and 2" Threaded Water Meters

Most 1-1/2" and 2" Threaded water meters have male threads with standardized AWWA male threads. These user standard round 1-1/2" or 2" meter couplings and gaskets by size. A couple manufactures make a FEMALE threaded version. In that case, special meter couplings with bushing are available by special order, and the meters are threaded with the NPT tapered pipe thread end of the meter coupling.

1-1/2" and 2" Flange End Water Meters

Flange end 1-1/2" and 2" meters have 2-bolt elliptical (oval) flanges. The bolts are on the two sides of the pipe horizontally. The bolts are 4" on center on the 1-1/2" flange and 4.5" on center on the 2" flange. Meters are installed with Companion Flanges with either male or female pipe threads. The gaskets can be either full face gaskets or drop-in style gaskets with ears on the top only.

Meter Gaskets

Meter Gaskets (or meter washers) are available in several different materials and thicknesses. It is ALWAYS recommended to change the meter gasket when installing or reinstalling a meter. Old gaskets will be compressed and may not seal resulting in leaks.


  • Rubber/Neoprene - The most common material used is Neoprene Rubber. Normally black or red in color. They are the least expensive, most common and seal and compress well in most situations. They are very flexible, but more difficult to handle when thin. The most common thickness is 1/8", and they are available in thin 1/16". It is not recommended to stack more than two to vary thickness. If 1/32" is needed, look to fiber gaskets.
  • Hard Fiber - Fiber gaskets are more rigid and can vary in color. The standard thickness is 1/16", but they are available in 1/32" and 1/8" as well. They can be stacked to vary for length error without squashing outward.
  • Leather - Many long time industry experts prefer leather gaskets. They are actual leather with a paraffin coating The standard thickness is 1/8", but thin 1/16" is available. They seal very well without as much compression as rubber. These work very well when the meter coupling or setter is not perfectly aligned.
  • EPDM - This is a newer synthetic rubber material that we can get by special order if your manufacturer or city specifies their use.
  • Polyethylene Plastic - Another hard plastic material available by special order.
  • Cloth inserted Rubber/Neoprene - The neoprene gaskets are available with a cloth reinforcement. The cloth keeps the rubber from stretching and stiffens it. We can get these by special order as well.

Gasket thickness

Thicknesses are available for meter gaskets / meter washers from 1/32" thick to 1/4" thick. If necessary, you can mix thicknesses to fill space as needed and allow for enough compression to seal water tight.

Gasket shape & size

All round "meter gaskets" are sized for compressing between a swivel meter coupling nut and the meter spud end. The meter gasket size generally refers to the Inside Diameter of the gasket which typically matches the flow capacity or bore size the meter. If you have a Yoke setting with an iron bar and and expansion wheel, standard meter gaskets will not work. You will need "Yoke End Gaskets for a Yoke setting. More info on yoke gaskets below.

Oval or Elliptical gaskets come in full face or drop-in style. With full face, the gasket totally surrounds the bolt hole. The gasket must be in place before pushing the bolts in the holes. With a drop-in gasket, the meter can be loosely bolted in place and then the gasket dropped in between the flanges. The gasket seals around the center hole where water flows, but only overlaps the top portion of the bolt hole.

Yoke Gaskets - If you have a Yoke setter, the gaskets on the two far ends are the same size and are called "Yoke End Gaskets" There is also an expansion wheel that threads onto on end of the meter, that has a gasket compressed between the wheel and meter spud. This is referred as the expansion wheel gasket and is smaller diameter than the yoke end gasket. They normally come with the expansion wheel, but may need to be replaced in a meter replacement if re-using the expansion wheel. Inside the nose of the expansion wheel is a beveled gasket. We can also get these by special order as well.

Please contact is before ordering if you have questions on proper meter coupling or gasket sizing.