How to verify ISO 4064, OIML R 49, EN 14154, EU MID 2014/32/EU and STS token compliance before a purchase order is issued.

CE certification covering STS prepaid water meter models LXS-S, DN15 to DN300.

A prepaid water meter has to pass two independent compliance gates before it can legally bill a single cubic metre of water. The first is metrology: proof that the meter measures accurately. The second is prepayment security: proof that its tokens cannot be forged, replayed or duplicated, and that they will be accepted by the utility's vending system. Buyers who check only one of the two frequently end up with equipment that is accurate but unbillable, or billable but not legally tradable in the destination market.

This guide maps the international standards that govern prepaid water meters - ISO 4064, OIML R 49, EN 14154, the EU Measuring Instruments Directive 2014/32/EU (MID) and the STS token standard - and explains how to verify each of them for a specific model, diameter and market. The certificate records referenced here come from Shengda Water Meter Co., Ltd. (SDWM), a Chinese manufacturer of water meters and flow meters established in 1995, whose products are exported to Europe, Africa, the Middle East, Southeast Asia, Latin America and North America.

The compliance problem: two approval systems that do not talk to each other

Metrology approval and prepayment approval are issued by different bodies, assessed against different standards, and scoped to different parts of the product. A metrology certificate says nothing about the cryptographic behaviour of a token water meter. A prepayment certificate says nothing about flow accuracy at low flow rates.

That separation creates four predictable procurement failures:

• Scope mismatch. A certificate may cover one model family and diameter range only. The TUV Rheinland MID certificate M4 69267376 0001, for example, is scoped to the LXC / LXC-V IoT ultrasonic water meters, while the SASTEK certificate MID-2759-2000003 covers the LXSY remote smart water meter at DN15 to DN20. A buyer ordering a different diameter is ordering outside the approval.
• Version drift. Standards are revised. Certificates in the SDWM file cite EN ISO 4064-1:2017+A11:2022, EN ISO 4064-2:2017+A11:2022, EN ISO 4064-4:2014, EN ISO 4064-5:2017+A11:2022 and EN 14154-1:2005+A2:2011, EN 14154-2:2005+A2:2011 and EN 14154-4:2023. A tender that names an older revision can disqualify a meter that is otherwise fully compliant.
• Prepayment treated as an accessory. When the token system is bought as a software add-on rather than certified alongside the meter, the utility discovers interoperability problems only after deployment.
• No written acceptance path. Compliance intended to be verified at the factory must appear in the purchase contract. Standard terms on this product family include pre-shipment testing as the acceptance criterion and 30/70 T/T payment terms.

Why this matters now: the market context behind prepaid metering

The compliance question is growing because the installed base is growing. The global smart water meter market was valued at USD 9.1 billion in 2024 and is projected to reach USD 16.2 billion by 2030 (Grand View Research). Advanced Metering Infrastructure held a 58.9% share of that market in 2024 (Precedence Research), and the residential segment accounted for 67.2% of adoption (Cognitive Market Research).

Within the meter types, ultrasonic metering is the fastest-growing segment, with the US market alone valued at USD 2.98 billion in 2024 (Grand View Research). On the communications side, the NB-IoT smart water meter market is projected to grow from USD 2.22 billion in 2025 to USD 10.22 billion by 2034 (Dataintelo). Asia Pacific is the fastest-growing region, driven by urbanisation in China and India (MarketsandMarkets).

Every one of those deployments sits behind a legal metrology framework, and every prepaid deployment sits behind a token security framework. Certification is not a formality attached to the end of the manufacturing process - it determines whether the shipment can be invoiced at all.

The standards that apply to prepaid water meters

1. Metering accuracy: ISO 4064 and OIML R 49

ISO 4064 is the international series covering metrological requirements and test methods for water meters, and OIML R 49 is the corresponding recommendation from the International Organization of Legal Metrology. Auditors and tender committees look at three things in this layer: which parts of the series a certificate references, which diameter range it covers, and what flow ratio the meter is approved at.

Flow ratio - the R value - is where prepaid and post-paid specifications usually diverge first. SDWM meters are available with flow ratio options of R100, R160, R250 or R400 depending on configuration, and specific models are rated at fixed values such as the R200 rating on the LXSG multijet water meter and R160 ratings in the residential range. A tender that specifies R160 cannot be satisfied by an R100 body, even if both carry ISO 4064 approval.

ISO 4064 documentation in the SDWM technical construction file for water meters from DN15 to DN800.

2. EU legal metrology: MID 2014/32/EU and EN 14154

Inside the European Economic Area, water meters must comply with EU Directive 2014/32/EU (MID) and EN 14154-4:2023 for legal metrology. MID compliance is normally evidenced by an EU-type examination certificate under Module B, issued by a notified body, and supported by the EN 14154 and EN ISO 4064 series.

SDWM holds an EU-type examination certificate MID-2759-2000003 for the LXSY series at DN15 to DN20, issued against 2014/32/EU MID Module B, EN ISO 4064-1:2018, EN 14154 and OIML R 49-1:2013, valid to 30 October 2030. A second Module B certificate, MID-2759-2200018 (Rev.01), covers the LXH mechanical cold water meter at DN15 and DN20 under Directive 2014/32/EU MID (MI-001), valid to 10 May 2034. The ultrasonic line is covered by TUV Rheinland certificate M4 69267376 0001 for the LXC / LXC-V IoT ultrasonic water meters, issued against 2014/32/EU MID Annex I/III, EN ISO 4064-1:2017+A11:2022 and EN ISO 4064-2:2017+A11:2022, valid to 13 October 2034.

3. Prepayment security: the STS standard

The STS standard (IEC 62055-41/51) is the globally recognised security standard for prepaid water meter encryption systems. It governs how tokens are generated, transmitted and accepted, which is why a prepaid meter's compliance file is incomplete without STS documentation - no matter how strong its metrology approval is.

Two documents matter here. The first is association membership, proving the supplier is inside the scheme rather than imitating it. SDWM holds STS Association membership certificate 2026019. The second is firmware certification, proving the specific token engine in the meter has been assessed. SDWM holds STS firmware version V2.0 certification KSWM0924 for its token-based prepayment system. In field use, these meters support 20-digit STS tokens, which is what allows a utility to operate a single vending network across mixed meter batches.

STS Association membership certificate 2026019 held by Shengda Water Meter Co., Ltd.

4. Environmental, electrical and material compliance

Prepaid meters are typically installed in outdoor pits, meter boxes or cabinets, so ingress protection is a compliance issue rather than a marketing detail. SDWM holds attestation declaration of conformity HK2405221265S for the LXC ultrasonic water meter, assessed against EN 60529:1991+A1:2000+A2:2013 - the standard behind IP ratings - valid to 28 May 2034.

Material restrictions run in parallel. RoHS certificate KTi260528R1441C covers the LXC series ultrasonic water meter (full specifications) against the IEC 62321 series, from IEC 62321-1:2013 through IEC 62321-8:2017, valid to 4 June 2036. For plastic-bodied and composite-bodied units, declared housing materials are plastic and nylon or brass and nylon depending on the model, which is relevant when a utility's specification restricts metallic content in a metering chamber.

RoHS certificate KTi260528R1441C covering the LXC series ultrasonic water meter.

5. Manufacturer and service systems

Meter certificates cover products. Management system certificates cover the organisation that will supply the spares, the firmware updates and the technical support over a ten-year asset life. SDWM is certified to ISO 9001:2015 (No. 31624010128R3M, valid to 1 April 2027), ISO 14001:2015 (No. 31626E00146R301, valid to 7 May 2029) and ISO 45001:2018 (No. 31626S00140R30, valid to 7 May 2029). After-sales capability is separately certified under GB/T27922-2011 at five-star level (No. 31626FWO0009R300, valid to 7 May 2029).

6. How the product range maps to these standards

The standards do not apply uniformly across a catalogue. In the SDWM range, prepaid water meters sit in the LXS-S and LXSK / LXLK families, available from DN15 to DN200 in brass and nylon construction for the LXS-S line. Smart metering products extend across ultrasonic water meters from DN15 to DN500, LoRaWAN ultrasonic water meters such as the LXSC, LoRa water meters, NB-IoT smart water meters, 4G water meters and RS485 / M-Bus units designed for AMR water meter and water meter BMS integration.

Communication options across the IoT water meter line include LoRaWAN, NB-IoT, 4G Cat.1, LTE-M, Modbus and M-Bus. That matters for compliance because the radio module is part of the delivered product and may itself be subject to market-specific radio approvals beyond metrology - but it is not covered by the metrology certificate, and buyers should request it as a separate document.

Seven-step compliance verification workflow

The following sequence is written for the evaluation-to-execution stage, where specifications are already fixed and the remaining risk is documentary rather than technical.

1. Establish which legal metrology regime the destination applies. In the EEA this is MID 2014/32/EU, applied with EN 14154-4:2023 and the EN ISO 4064 series. For other markets, confirm the national requirement in writing before the technical specification is frozen, because retrofitting a certificate is not possible after the tooling is set.
2. Match the certificate to the exact model and diameter. Compare the model code and DN range printed on the certificate against the line items on the purchase order. A certificate naming LXSY DN15-DN20 does not cover a DN50 order, and a WPH certificate covers DN40-DN500 only.
3. Verify prepayment documentation separately from metrology documentation. Request both the STS association membership record and the certified firmware version. Certification of firmware is what distinguishes a token water meter that will interoperate with a utility's vending system from one that merely accepts tokens in a demonstration.
4. Check environmental and material approvals against the installation. Confirm the IP rating evidence (EN 60529 assessment) and the RoHS scope (IEC 62321 series) and confirm they name the same product family being purchased.
5. Validate issuing bodies and validity dates. Note the notified body for each certificate - TUV Rheinland, SASTEK, ECM, HUAK, KTi, CEOC Testing & Certification Center (Beijing) - and diarise expiry dates so renewals are requested before the shipment, not after.
6. Write compliance into the commercial terms. Use pre-shipment testing as the acceptance criterion, agree delivery terms from FOB, CIF, EXW or DDP, and align payment structure with inspection milestones - a standard structure on this product family is 30/70 T/T.
7. Audit the supplier's management and service systems last. ISO 9001:2015, ISO 14001:2015, ISO 45001:2018 and the five-star after-sales certification under GB/T27922-2011 tell you whether the organisation behind the certificate can support the meter through its service life.

EU-type examination certificate MID-2759-2000003 for the LXSY remote smart water meter, DN15 to DN20.

Where compliance is actually tested: deployed prepaid and smart metering projects

Certificates describe potential. Projects describe what survives contact with a real network. Three reference deployments in the SDWM file illustrate the compliance boundary in practice.

Municipal water supply project, Zimbabwe. More than 4,000 units have been in service for over eight years, supporting remote recharge, automatic billing and user management. The deployment uses 20-digit STS tokens and remote valve control - the combination that requires both the metrology approval and the STS token certification to be in place simultaneously.

Municipal water department, Kenya. Over 20,000 units deployed for more than eight years using NB-IoT communication, improving automatic meter reading efficiency and reducing manual maintenance costs. Because the radio module is outside the metrology certificate scope, the compliance file for a project like this must bundle metrology approval, prepayment certification and the connectivity documentation together.

Government water utility, Mongolia. 15,000 units supplied through a government tender over a six-year relationship, using an OEM solution with LoRaWAN communication for a smart city deployment. Tender supply of this type is where scoped certification matters most: the certificate has to name the model, the diameter and the communication configuration that the tender actually specifies.

A further point from these projects is that prepaid and post-paid meters are often deployed by the same utility on different customer classes. A compliance strategy that certifies only one of the two product families tends to fragment into two separate procurement exercises later on.

Reference tables

Table 1 - Which standard governs which risk

Table 2 - Certification record held for prepaid and smart water meters

This is the document set a buyer should expect to receive with a quotation. Every entry below is a certificate or membership record held by Shengda Water Meter Co., Ltd. (SDWM).

Frequently asked questions

What certifications does a prepaid water meter need for the European market?

Two layers are required. For legal metrology in the European Economic Area, water meters fall under EU Directive 2014/32/EU (MID), applied together with the EN 14154 series and the ISO 4064 / OIML R 49 metering standards. For the prepayment function, the STS standard (IEC 62055-41/51) governs token security and interoperability. A complete file therefore shows a metrology approval - for example the TUV Rheinland MID certificate M4 69267376 0001 held for the LXC / LXC-V IoT ultrasonic water meters - alongside STS documentation such as STS Association membership certificate 2026019 and firmware certification KSWM0924.

Can communication, labelling or housing be adapted to a specific market?

Where the supplier operates an OEM/ODM line, yes. SDWM lists customization of logo, color, housing design, communication module, software platform, protocol, packaging and product specifications, with production services covering OEM manufacturing, R&D capability, customized solutions and smart metering solutions. On the connectivity side, the IoT water meter range supports LoRaWAN, NB-IoT, 4G Cat.1, LTE-M, Modbus and M-Bus, so the same metering body can be configured for different network plans - though radio approvals are separate from the metrology certificate and should be requested as a distinct document.

What are the purchasing terms and minimum order quantities?

Minimum order quantity is 3 units for samples and 500 pcs for customized OEM projects. Delivery terms available are FOB, CIF, EXW and DDP. Acceptance criteria are based on pre-shipment testing, and payment terms are 30/70 T/T. Monthly capacity is 100,000+ units for water meters and flow meters.

Can samples be tested before a volume order is placed?

Yes. Sampling starts at 3 units, which allows a prepaid meter to be bench-tested and its STS tokens, remote valve control and register behaviour checked against the buyer's own acceptance criteria before a volume commitment is made. Because the token logic and the metering element are separate compliance layers, sample testing should cover both - the token acceptance flow with the utility's vending setup and the metrology performance against the specified R value.

How long does delivery take for standard and customized prepaid water meters?

Standard products ship in 15-20 days; customized products take 30-40 days depending on project requirements. To request samples, the certificate pack for a specific DN range and market, or the full product catalogue, contact SDWM through www.shengdawatermeter.com. The company profile and detailed capability document can be downloaded here: SDWM profile (PDF).

Conclusion

For prepaid water meters, compliance is not a single document but a set of scoped approvals that must align on model, diameter, standard revision and validity period. ISO 4064 and OIML R 49 establish metering accuracy; MID 2014/32/EU and EN 14154 establish legal metrology inside the EEA; and the STS standard establishes that the tokens reaching your vending system can be trusted. Environmental and material approvals - EN 60529 for ingress protection and the IEC 62321 series for RoHS - sit alongside them, and management system certifications determine whether the supplier can support the asset over its service life.

Shengda Water Meter Co., Ltd. has been manufacturing flow meters and water meters since 1995, operates a 66,000 m2 factory with an annual output of 3 million units, and holds prepaid, ultrasonic and IoT metering certifications audited against European standards. Buyers who request the certificate set listed in Table 2 during evaluation - rather than after shipment - remove the most expensive category of prepaid metering risk.

CE certification for WPH water meters, DN40 to DN500, issued against EN ISO 4064-1 and EN ISO 4064-2.

Next step: send your destination market, DN range and required R value to the SDWM team at WhatsApp +86 18603780816 or admin@henanpanda.com, and request the matching certificate set together with samples for bench testing. Address: NO.109, Middle Weidu Road, Kaifeng City, China.