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WRAS, MID & Accuracy Explained

What is WRAS Approval?

Any water fitting when installed that carries or receives water from the public mains water supply in the UK, must comply with the Water Supply (Water Fittings) Regulations or Scottish Byelaws. These require that a water fitting should not cause waste, misuse, undue consumption or contamination of the water supply and must be of an appropriate quality and standard.

WRAS Approval is the easiest way to demonstrate compliance as it is granted directly by representatives of the water suppliers and is therefore accepted by every water supplier in the UK. WRAS Product Approval: Whole products such as valves, boilers & showers undergo mechanical and water quality testing. This type of approval demonstrates full compliance with requirements of the regulations and byelaws, provided the fitting is installed according to any conditions given with the approval.

WRAS Material Approval: Non-metallic materials & components, such as rubber sheet material & ‘O’ rings, undergo testing only for their effects on water quality. This type of approval demonstrates that the non-metallic material/component does not itself contaminate the water and therefore satisfies this particular requirement of regulations and byelaws.

WRAS approval applies to both cold and hot water meters.

What is MID Approval?

MID is the Measuring Instruments Directive which is a European Directive which harmonises the requirements of ten different measuring instrument types for domestic, commercial and light industrial use.

MID approvals provide manufacturers with a single approval certificate which is valid throughout Europe. These measuring instrument types include:

  • Water Meters
  • Gas Meters & Volume Conversion Devices
  • Active Electrical Energy Meters
  • Heat Meters
  • Measuring Systems for the continuous and dynamic measurement of liquids other than water
  • Automatic Weighing Instruments
  • Taxi Meters
  • Material Measures
  • Dimensioning Systems
  • Exhaust Gas Analysers

MID approved meters, which include primary and secondary sub-meters, must satisfy specific conformity assessment procedures and have MID markings which allow the instruments to be used for fiscal billing purposes in any EU member state.

Meters already installed, that were approved under UK National legislation prior to October 2006 may remain installed indefinitely, as long as they are measuring accurately. Any new meter manufactured and approved after October 2006 must be approved under the MID regulations.

It is a criminal offence to use a non-approved meter for fiscal billing purposes, carrying a potential fine of £1,000 per non-MID meter. A consumer is also within their rights to refuse payment on a non-MID meter.

How do I know my meter is MID Approved?

All MID approved meters will be stamped with a MID Approval Mark, as shown as an example in the image below.



The MID Approval Mark will be made up of the CE or EU Consumer Safety Directive Compliance mark followed by the MID ‘M’ metrology mark, plus 2-digit year of manufacture and finally a 4 digit Approving Notified Body reference number. MI-001 applies to water meters.

What does the Accuracy class of a water meter mean?

Water meter accuracy is denoted by "R" followed by a number. The higher the number the more accurate the water meter. For example an R800 meter is much more accurate than a R160 meter. It is important to note that the way a meter is installed can affect its accuracy class. For example, multi jet water meters are more accurate when they are installed in a horizontal pipe with the dial facing upwards than they are if they are installed in a vertical pipe. The product data sheet will show you the R accuracy class on all of our products.

Please note that some suppliers do not provide the accuracy class of their meters when installed in certain positions so be careful when selecting meters and give consideration to how you intend to install it. As a guide, an R80 meter has poor accuracy and often when they are installed vertically they become R40 accuracy which is worse.