| Item | Detail |
|---|---|
| Dominant thread | G1/2 (BSPP, ISO 228) parallel thread, head side outside diameter about 27 mm, sealing on a washer or cone face rather than on the threads |
| North America | Shower arms commonly carry 1/2 inch NPT tapered thread; the hose supply end or an adapter is the conversion point |
| Adapter set | Four types, all G1/2 on the head side: S = M22.1 x 1.5, G = M21.3 x 1.5, K = M21.5 x 2, M = M22.1 x 1.75 |
| US flow rule | A federal maximum of 2.5 gpm per shower head commonly applies; WaterSense is voluntary at 2.0 gpm or less, with 1.8 gpm in the revised specification |
| Canada | A 2.5 gpm (about 9.5 L/min) ceiling is commonly applied nationally, with 1.8 gpm (about 6.8 L/min) usual in British Columbia and Ontario |
| Europe | No single national flow ceiling for shower heads; water saving models are commonly listed around 6 to 9 litres per minute |
| The one mandatory scheme to plan early | WaterMark plus WELS registration for Australia and New Zealand, which belongs in the first RFQ conversation |
| Factory reference conditions | Flow tested at 0.3MPa for selected specifications; leak point checks at 0.5MPa in selected processes |
Read the Thread, Not the Country
A thread designation carries three facts: nominal size, thread form, and whether the thread is parallel or tapered. G1/2 is parallel, from the BSPP family defined in ISO 228, with a head side outside diameter of about 27 mm. It does not seal on the threads: the cone nut seats into the head inlet, and the hex nut compresses a washer against the mixer outlet.
1/2 inch NPT is tapered, and the taper is the point: the flanks interfere as the joint tightens, so the seal is made on the threads with tape or sealant. G1/2 and NPT share a nominal size and nothing else.
Japanese naming causes the most confusion on a first order. Current Japanese products commonly carry G1/2 at the hose connection, while JIS designations such as PJ1/2 belong to the tapered pipe thread family in Japanese fitting standards, and older faucets use maker specific fittings. Pack an adapter set and confirm against the actual faucet model.
| Connection | Thread form | Where it is native or used | Sealing and dimensions |
|---|---|---|---|
| G1/2 (BSPP, ISO 228) | Parallel | Europe, the UK, most of Asia, Oceania, Africa and Latin America; hand showers and hoses almost everywhere | Seals on a rubber washer at the mixer end and a cone face at the head end; head side outside diameter about 27 mm |
| 1/2 inch NPT | Tapered | United States, Canada and Mexico shower arms; Gulf projects specified to United States standards | Seals on thread interference with tape or sealant; nominal 1/2 inch, not interchangeable with G1/2 |
| JIS naming such as PJ1/2 | Tapered pipe thread family in Japanese fitting standards | Japan, alongside G1/2 hose connections on current products | Confirm against the faucet model; older Japanese faucets use maker specific fittings |
| ZHONGHE adapter set (S, G, K, M) | Metric parallel on the fitting side, G1/2 on the head side | Legacy and non standard fittings in any market | S = M22.1 x 1.5, G = M21.3 x 1.5, K = M21.5 x 2, M = M22.1 x 1.75 |
Thread by Market
The table below sorts markets by what the wall gives you and what the hand shower gives you. Almost everywhere the hand shower and the hose are G1/2, and the only real question is what happens at the wall.
Two rows repay a second look. Mexico follows United States practice at the arm while using G1/2 on hand showers and hoses. Colombia and the Philippines carry both conventions in the same housing stock.
| Market | Wall outlet or shower arm | Hand shower and hose | Conversion point |
|---|---|---|---|
| United States and Canada | 1/2 inch NPT tapered on shower arms | G1/2 | Hose supply end or an adapter |
| Mexico | 1/2 inch NPT tapered, following United States practice | G1/2 | Hose supply end or an adapter |
| United Kingdom | 1/2 inch BSP, the same parallel thread as G1/2 | G1/2 | None needed; riser rails commonly 25 mm |
| Germany, France, Spain, Italy, Netherlands, Poland | G1/2 (BSPP, ISO 228) at the mixer outlet | G1/2 | None needed; rails commonly 25 mm |
| Russia and Turkey | G1/2, written as half an inch in local catalogs | G1/2 | None needed; rails commonly 25 mm |
| United Arab Emirates and Saudi Arabia | G1/2 usually; 1/2 inch NPT on projects specified to United States standards | G1/2 | State whether the order is retail or project |
| India, Nigeria, South Africa, Australia | 1/2 inch BSP or G1/2 | G1/2 | None normally needed; S, G, K and M cover legacy fittings |
| Japan | G1/2 on current products; maker specific fittings on older faucets | G1/2 | Adapter set normally packed with the head |
| South Korea | G1/2 | G1/2 | S, G, K and M for older apartment fittings |
| Vietnam, Thailand, Indonesia, Malaysia and Singapore | G1/2 (BSPP) | G1/2 | Confirm the heater outlet where the head connects to a wall heater |
| Brazil, Chile, Argentina | 1/2 inch connections | G1/2 | Confirm the wall fitting with the importer |
| Colombia and the Philippines | Both NPT tapered and BSP parallel in use | G1/2 shipped by default | Conversion point specified per order |
Flow Limits and Labels by Market
A flow limit is a legal ceiling. A flow label is a marketing permission with rules attached. Confusing the two is the most common mistake here, because a product can be entirely legal and still be unable to carry the label a retailer wants on the box.
Numbers only mean something with a pressure attached. ZHONGHE flow tests selected specifications at 0.3MPa (3 bar, about 43.5 psi), where water saving specifications have measured roughly 50 to 70 percent below comparable non water saving heads. Where a market rule names its own reference pressure, that is the condition the compliance figure has to be produced at.
Every row below is an orientation reference, not a legal opinion. Confirm the current requirement with your compliance adviser or customs broker before artwork is printed.
| Market | Mandatory flow rule | Label or scheme | Practical note |
|---|---|---|---|
| United States | A federal maximum of 2.5 gpm per shower head commonly applies | EPA WaterSense, voluntary, at 2.0 gpm or less with 1.8 gpm in the revised specification | Several states typically apply 1.8 gpm; confirm the current state rule |
| Canada | A 2.5 gpm (about 9.5 L/min) ceiling is commonly applied nationally | Provincial building codes typically go lower | 1.8 gpm (about 6.8 L/min) is usual in British Columbia and Ontario |
| Mexico | NOM-008-CONAGUA-1998 is commonly cited, with a maximum flow at a stated test pressure | NOM conformity verified by accredited bodies | State the target flow together with the pressure it must be met at |
| United Kingdom | No single national flow ceiling applies to shower heads | The Water Fittings Regulations govern the fitting itself | Gravity systems can run near 0.1MPa, so specify a flow at a stated pressure |
| Germany, France, Spain, Italy, Netherlands, Poland | No single national flow ceiling applies | Retail listings commonly quote water saving models around 6 to 9 litres per minute | Spanish regional drought restrictions sometimes set stricter targets |
| Australia and New Zealand | WELS registration and labelling commonly apply to showers | Star rating driven by flow in litres per minute | The band boundaries are set by the scheme; confirm the current band table before a star goes on artwork |
| Singapore | A mandatory water efficiency labelling scheme covers showerheads | Administered by the water utility | Malaysian specifications increasingly reference efficiency as well |
| Japan | No mandatory maximum is commonly applied | 節水 is a headline retail claim | JIS standards cover faucet fittings and are commonly referenced for method rather than as a flow ceiling; confirm the applicable reference |
| South Korea | No mandatory maximum is commonly applied | 절수 is a recognised selling point | The figure has to be stated with its test conditions |
| Saudi Arabia and United Arab Emirates | Water efficiency requirements apply to shower fittings and a flow limit with an efficiency label is commonly enforced | SABER against SASO requirements; ECAS in the Emirates | Confirm the current limit and label format with your conformity assessment body before artwork |
| India, Brazil, South Africa, Nigeria, Vietnam, Thailand, Indonesia, Philippines | No mandatory shower flow maximum is commonly applied | No efficiency label is usually required | Tank fed supply makes low pressure performance the real constraint rather than the ceiling |
Water Fitting Schemes by Country
Schemes are granted for a product to an applicant, normally the brand or the importer, and not to a factory in general. ZHONGHE supports an application with samples, drawings and bills of materials, supplies component test reports, and arranges third party testing per project; certified options are available on request.
One entry differs in kind. WaterMark for Australia and New Zealand is genuinely mandatory for plumbing products, so it belongs in the first RFQ conversation. Everything else is either a wetted material question answered by the bill of materials, or an import route the importer runs.
| Market | Scheme or route | What it covers |
|---|---|---|
| United States | NSF/ANSI 61 and 372; cUPC or IAPMO listing; California Proposition 65 | Wetted materials and lead content; wholesaler and code listings; a warning duty on the party placing the product on the market |
| Canada | CSA B125.1 and ASME A112.18.1; cUPC or CSA listing | Referenced by the National Plumbing Code; bilingual English and French labelling is commonly required |
| United Kingdom | WRAS approval or an equivalent Regulation 4 route; BS EN 1112 and BS EN 1113 | Water fittings connected to the supply; shower outlets and hoses |
| Germany, Austria, Switzerland | DVGW, with ÖVGW in Austria and SVGW in Switzerland; KIWA as a further route; UBA material recommendations | Drinking water fittings and wetted materials |
| France | ACS, the attestation de conformité sanitaire; the NF mark as a voluntary route | Materials in contact with drinking water |
| Netherlands and Belgium | Kiwa and Belgaqua | Products in contact with drinking water |
| Spain | AENOR against UNE-EN 1112 and UNE-EN 1113, voluntary | Product conformity; the Código Técnico de la Edificación governs installation |
| Italy | UNI EN 1112 and UNI EN 1113, plus national rules on materials in contact with drinking water | Shower outlets, hoses and wetted parts |
| Poland | A hygienic attestation from the national public health institute; PN-EN 1112 and 1113 | Products in contact with drinking water |
| Russia and the Eurasian Economic Union | EAC mark on a declaration or certificate; GOST standards referenced | Sanitary products across Russia, Belarus, Kazakhstan, Armenia and Kyrgyzstan |
| Turkey | TSE mark or TS EN 1112 and TS EN 1113 test evidence | Distributor and public tender requirements; imports screened at customs |
| United Arab Emirates | ECAS, with the Emirates Quality Mark as the higher tier | Regulated products; municipality approval can apply on building projects |
| Saudi Arabia | SASO requirements shown through the SABER platform | A product certificate of conformity, then a shipment certificate issued before arrival |
| Australia and New Zealand | WaterMark certification plus WELS registration | Plumbing products installed in Australia and New Zealand; the flow label |
| India | BIS, the ISI mark and Quality Control Orders | A widening list of goods; confirm current coverage for your tariff line |
| Brazil | INMETRO conformity schemes | Compulsory programmes focus on electrical products such as the chuveiro elétrico |
| Mexico | NOM conformity; NOM-050-SCFI | Commercial information on the label in Spanish |
| Japan | JIS standards and the Water Supply Act framework | Faucet fittings; leaching test methods for wetted materials |
| South Korea | KC certification; the Water Supply Act hygiene safety standard route | Designated product categories and waterworks materials |
| Malaysia and Singapore | SIRIM and SPAN; the Singapore water utility approves water fittings | Fittings used in the reticulation system; the Singapore efficiency label |
| Indonesia, Thailand, Vietnam, Philippines | SNI and SPPT SNI; TISI; TCVN and QCVN; the BPS PS mark and Import Commodity Clearance | National standards routes, mandatory for listed product groups |
| Nigeria, South Africa, Egypt | SONCAP with Form M and PAAR; SABS and SANS with JASWIC listing; importer or brand registration with the national import authority | Pre shipment certification and listings for water fittings |
What to Put in the RFQ
Seven lines turn this reference into a buildable specification, and each changes the tooling, the bill of materials or the artwork.
- Name the wall fitting rather than the country: shower arm thread, mixer outlet thread, and whether the head screws directly to the wall.
- State the thread for each end of every item in the order, since a head, a hose and a holder can each carry a different one.
- Give a target flow with the pressure it must be met at, and name the reference condition your market rule uses.
- Say which label the product must be able to carry, because a label criterion is usually stricter than the legal ceiling underneath it.
- Name the scheme the destination requires and who will hold the approval, since it is granted to an applicant rather than to a factory.
- Decide which adapters ship in the box, and write the compatibility statement that will appear on the packaging.
- Confirm every rule quoted here with your own compliance adviser or customs broker before artwork goes to print.