Handbook 44 – 2009 3.36. Water Meters 

Section 3.36. Water Meters 

A. Application 

A.1. This code applies to devices used for the measurement of water; generally applicable to, but not limited to, utilities 

type meters installed in residences or business establishments and meters installed in batching systems. 

(Amended 2002) 

A.2. This code does not apply to: 

(a) water meters mounted on vehicle tanks (for which see Section 3.31. Code for Vehicle-Tank Meters) or 

(b) mass flow meters (see Section 3.37. Code for Mass Flow Meters). 

(Added 1994) 

A.3. See also Section 1.10. General Code requirements. 

S. Specifications 

S.1. Design of Indicating and Recording Elements and of Recorded Representations.

S.1.1. Primary Elements.

S.1.1.1. General. – A water meter shall be equipped with a primary indicating element and may also be 

equipped with a primary recording element. Such elements shall be visible at the point of measurement or be 

stored in non-volatile and nonresettable memory. The display may be remotely located provided it is readily 

accessible to the customer. 

(Amended 2002) 

S.1.1.2. Units. – A water meter shall indicate and record, if the device is equipped to record, its deliveries in 

terms of liters, gallons or cubic feet or binary or decimal subdivisions thereof except batch plant meters, which 

shall indicate deliveries in terms of liters, gallons or decimal subdivisions of the liter or gallon only. 

S.1.1.3. Value of Smallest Unit. – The value of the smallest unit of indicated delivery and recorded delivery, if 

the device is equipped to record, shall not exceed the equivalent of: 

(a) 50 L (10 gal) on utility type meters, 

(b) 0.2 L (1

/10 gal) on batching meters delivering less than 375 L/min (100 gal/min), or 

(c) 5 L (1 gal) on batching meters delivering 375 L/min (100 gal/min) or more. 

S.1.1.4. Advancement of Indicating and Recording Elements. – Primary indicating and recording elements 

shall be susceptible to advancement only by the mechanical operation of the device. 

S.1.1.5. Return to Zero. – If the meter is so designed that the primary indicating elements are readily returnable 

to a definite zero indication, means shall be provided to prevent the return of these elements beyond their correct 

zero position. 

S.1.2. Graduations.

S.1.2.1. Length. – Graduations shall be so varied in length that they may be conveniently read. 

S.1.2.2. Width. – In any series of graduations, the width of a graduation shall in no case be greater than the 

width of the minimum clear interval between graduations, and the width of main graduations shall be not more 

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than 50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 0.2 mm 

(0.008 in) in width. 

S.1.2.3. Clear Interval Between Graduations. – The clear interval shall not be less than 1.0 mm (0.04 in). If 

the graduations are not parallel, the measurement shall be made: 

(a) along the line of relative movement between the graduations at the end of the indicator, or 

(b) if the indicator is continuous, at the point of widest separation of the graduations. 

S.1.3. Indicators.

S.1.3.1. Symmetry. – The index of an indicator shall be symmetrical with respect to the graduations, at least 

throughout that portion of its length associated with the graduations. 

S.1.3.2. Length. – The index of an indicator shall reach to the finest graduations with which it is used, the width 

of the minimum clear interval between graduations, and the width of main graduations shall be not more than 

50 % greater than the width of subordinate graduations. Graduations shall in no case be less than 0.2 mm 

(0.008 in) in width. 

S.1.3.3. Width. – The width of the index of an indicator in relation to the series of graduations with which it is 

used shall not be greater than: 

(a) the width of the narrowest graduation*, and 

[*Nonretroactive as of January 1, 2002]

(Amended 2001) 

(b) the width of the minimum clear interval between graduations. 

When the index of an indicator extends along the entire length of a graduation, that portion of the index of the 

indicator that may be brought into coincidence with the graduation shall be of the same width throughout the 

length of the index that coincides with the graduation. 

S.1.3.4. Clearance. – The clearance between the index of an indicator and the graduations shall in no case be 

more than 1.5 mm (0.06 in). 

S.1.3.5. Parallax. – Parallax effects shall be reduced to the practicable minimum. 

S.2. Design of Measuring Elements.

S.2.1. Provision for Sealing. – Adequate provision shall be made for applying security seals in such a manner that 

no adjustment or interchange may be made of: 

(a) any measurement elements, and 

(b) any adjustable element for controlling delivery rate when such rate tends to affect the accuracy of deliveries. 

The adjusting mechanism shall be readily accessible for purposes of affixing a security seal. 

S.2.2. Batching Meters Only.

S.2.2.1. Air Elimination. – Batching meters shall be equipped with an effective air eliminator. 

S.2.2.2. Directional Flow Valves. – Valves intended to prevent reversal of flow shall be automatic in operation. 

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S.2.3. Multi-Jet Meter Identification. – Multi-Jet water meters shall be clearly and permanently marked as such on 

the device or identified on the Certificate of Conformance. 

(Added 2003) 

N. Notes 

N.1. Test Liquid. – A meter shall be tested with water. 

N.2. Evaporation and Volume Change. – Care shall be exercised to reduce to a minimum, evaporation losses and 

volume changes resulting from changes to temperature of the test liquid. 

N.3. Test Drafts. – Test drafts should be equal to at least the amount delivered by the device in 2 minutes and in no case 

less than the amount delivered by the device in 1 minute at the actual maximum flow rate developed by the installation. 

The test draft sizes shown in Table N.4.1. Flow Rate and Draft Size for Water Meters Normal Tests, shall be followed as 

closely as possible. 

(Amended 2003) 

N.4. Testing Procedures. 

N.4.1. Normal Tests. – The normal test of a meter shall be made at the maximum discharge rate developed by the 

installation. Meters with maximum gallon per minute ratings higher than the values specified in Table N.4.1. Flow 

Rate and Draft Size for Water Meters Normal Tests may be tested up to the meter rating, with meter indications no 

less than those shown. 

(Amended 1990, 2002, and 2003) 

Table N.4.1. Flow Rate and Draft Size for Water Meters 

Normal Tests 

Maximum Rate 

Meter Indication/Test Draft 

Meter Size 

(inches) 

Rate of Flow 

(gal/min) 

gal ft3

Less than 5/8 8 50 5 

 5/8 15 50 5 

 3⁄4 25 50 5 

1 40 100 10 

 11⁄2 80 300 40 

2 120 500 40 

3 250 500 50 

4 350 1000 100 

6 700 1000 100 

(Table Added 2003) 

N.4.1.1. Repeatability Tests. – Tests for repeatability should include a minimum of three consecutive test drafts 

of approximately the same size and be conducted under controlled conditions where variations in factors, such as 

temperature, pressure, and flow rate are reduced to the extent that they will not affect the results obtained. 

(Added 2002) 

N.4.2. Special Tests. – Special tests to develop the operating characteristics of meters may be made according to the 

rates and quantities shown in Table N.4.2. Flow Rate and Draft Size for Water Meters Special Tests. 

(Amended 2003) 

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3.36. Water Meters Handbook 44 – 2009 

Table N.4.2. Flow Rate and Draft Size for Water Meters 

Special Tests 

Intermediate Rate Minimum Rate 

Meter Indication/Test Draft Meter Indication/Test Draft Meter Size 

(inches) Rate of Flow 

(gal/min) gal ft3

Rate of Flow 

(gal/min) gal ft3

Less than or 

equal to 5

/8 2 10 1 1⁄4 5 1 

 3⁄4 3 10 1 1⁄2 5 1 

1 4 10 1 3⁄4 5 1 

 11⁄2 8 50 5 11⁄2 10 1 

2 15 50 5 2 10 1 

3 20 50 5 4 10 1 

4 40 100 10 7 50 5 

6 60 100 10 12 50 5 

(Table Added 2003) 

N.4.3. Batching Meter Tests. – Tests on batching meters should be conducted at the maximum and intermediate 

rates only. 

T. Tolerances 

T.1. Tolerance Values. – Maintenance and acceptance tolerances shall be as shown in Table T.1. Accuracy Classes and 

Tolerances for Water Meters. 

(Amended 2003) 

Table T.1. Accuracy Classes and Tolerances for Water Meters 

Accuracy 

Class 

Application Acceptance 

Tolerance 

Maintenance 

Tolerance 

Tolerance for Special 

Tests Conducted at the 

Minimum Flow Rate 

Overregistration 1.5 % 1.5 % 1.5 % 

1.5 

Water, Other 

Than Multi-Jet

Water Meters Underregistration 1.5 % 1.5 % 5.0 % 

Overregistration 1.5 % 1.5 % 3.0 % 

1.5 Water, Multi-Jet 

Water Meters 

Underregistration 1.5 % 1.5 % 3.0 % 

(Table Added 2003) 

T.1.1. Repeatability. – When multiple tests are conducted at approximately the same flow rate, the range of the test 

results shall not exceed 0.6 % for tests performed at the normal and intermediate flow rates, and 1.3 % for tests 

performed at the minimum flow rate, and each test shall be within the applicable tolerance. 

(Added 2002) 

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UR. User Requirements 

UR.1. Batching Meters Only.

UR.1.1. Strainer. – A filter or strainer shall be provided if it is determined that the water contains excessive 

amounts of foreign material. 

UR.1.2. Siphon Breaker. – An automatic siphon breaker or other effective means shall be installed in the discharge 

piping at the highest point of outlet, in no case below the top of the meter, to prevent siphoning of the meter and 

permit rapid drainage of the pipe or hose. 

UR.1.3. Provision for Testing. – Acceptable provisions for testing shall be incorporated into all meter systems. 

Such provisions shall include a two-way valve, or manifold valving, and a pipe or hose installed in the discharge line 

accessible to the proper positioning of the test measure. 

UR.2. Accessibility of Customer Indication. – An unobstructed standing space of at least 76 cm (30 in) wide, 91 cm 

(36 in) deep, and 198 cm (78 in) high shall be maintained in front of an indication intended for use by the customer to 

allow for reading the indicator. The customer indication shall be readily observable to a person located within the 

standing space without necessity of a separate tool or device. 

(Added 2008) 

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