A tin barrier between potable water and the lead in brass. Documented batch by batch, with reference to D.M. 174/2004 and, when required, the Arrêté Étamage 2018.
Fittings manufacturers
Barrel plating capacity
Pre-series lead time
01 / The problem
CW617N brass (commercially OT58), the standard alloy for compression fittings, valves and manifolds, contains around 2% lead (1.6-2.5%) to ensure machinability. It is a technological compromise that has lasted for decades: without lead, brass is difficult to drill, thread and hot-stamp.
On prolonged contact with potable water, especially when acidic, low in salts or oxygenated, lead is released through surface leaching. In parallel, on certain alloys, zinc migrates selectively, giving rise to dezincification. These are two distinct phenomena, both documented by European regulations for over twenty years.
Directive (EU) 2020/2184 on the quality of water intended for human consumption sets the lead limit at 10 µg/L today. From 2036 it will drop to 5 µg/L. For fittings manufacturers, documenting the functional barrier between alloy and water, batch by batch, becomes essential.
⌁ EU lead threshold
The lead limit in potable water in the EU from 2036.
It was 25 µg/L in 1998. An 80% reduction in just under forty years.
Historical evolution · µg/L
Electrolytic tin plating physically solves the problem. Pure tin, non-toxic and long used to coat the inside of food cans, is deposited on the fitting's surface, forming a continuous barrier. Direct contact between water and brass is reduced through a continuous metallic barrier.
02 / Regulations
More than 15 Italian fittings manufacturers entrust us with their tin plating. They export across Europe, sometimes overseas: each market has its own reference regulation, and our process documentation covers them all.
Italian Ministry of Health Decree governing the suitability requirements for materials and objects used in fixed installations in contact with water intended for human consumption.
European directive on the quality of water intended for human consumption. It sets chemical and microbiological parameters and the regime for the progressive lowering of the lead limit from 10 to 5 µg/L by 2036.
French decree defining the chemical composition allowed for tin used in the tin plating of components intended for contact with potable water, setting very strict limits for lead, antimony, arsenic and cadmium.
DVGW technical worksheet for assessing microbiological growth on organic materials or materials with organic constituents in contact with potable water. The main reference for the German market.
European standard defining the standard method for assessing the influence of metallic materials on the quality of potable water, by means of a dynamic test rig with alternating flow and stagnation cycles that simulate a domestic distribution system.
Scheme shared by Germany, France, the Netherlands, the United Kingdom and Denmark that publishes a positive list of metallic alloys accepted for contact with potable water in these jurisdictions.
North American standard on potable water system components and their health effects. The main reference for those exporting fittings to the United States.
03 / Process
Tin plating for hydrosanitary use is not a simple deposition of tin onto brass. Between the base metal and the functional layer, an underlayer of copper is interposed.
Tin adheres better to copper than to brass. Reduced porosity.
Hinders the migration of zinc and lead from the brass towards the upper layer.
Copper is ductile and absorbs the micro-stresses of mechanical assembly.
Coating cross-section
typical values
Typical Sn thickness
Sn purity
Traceability
Indicative thicknesses. Actual values are agreed with the client based on component specifications, expected service life and the contact water profile.
04 / The method
Shared only with other compatible treatments. The copper and tin baths maintain stable parameters over time: composition, temperature, current density. For the client this means repeatability between batches: the most difficult parameter to guarantee in industrial electroplating.
02 · Daily capacity
Sufficient to serve the main Italian fittings manufacturers. Typical pre-series lead times: 5-10 working days, adjustable based on volumes and priorities.
For each cycle: dwell time, applied current, temperature, operator.
Thickness (FischerScope XRF) · Adhesion (UNI EN ISO 2819) · Raw material purity (Arrêté Étamage 2018).
Bath and thickness analysis in-house. Migration tests entrusted to an accredited third-party laboratory.
05 / Process selection
The choice depends on several factors. The main ones are unit weight (under 150-200 grams it is generally barrel plating), geometry (deep internal cavities and multi-way components require the rack to ensure uniform coverage) and the surface finish allowed by the specifications: contact between parts during barrel rotation can leave micro-marks and, when the client excludes them, even small components are processed on the rack. For our hydrosanitary clients the typical split is approximately 85% barrel plating, 15% static rack.
High volumes, compact geometries, competitive cost.
Large parts, complex geometries, preserved finish.
06 / Components
For the hydrosanitary sector we treat several types of components, with widely varying geometries and diameters. A dedicated process line, two complementary techniques (barrel plating and static rack) depending on the geometry.
3-way male T with BSPP gas threads. Diameters 1/8"–2".
Brass 90° elbow with double male grooved connector. For water systems.
3-way T for press-fit multilayer pipework. Symmetrical geometry, medium-high volumes on barrel plating.
90° elbow with female threads on both sides. Typical for domestic plumbing.
90° elbow with one male grooved end and one female-threaded end.
07 / Base materials
The brass used in hydrosanitary fittings comes in three main families, distinguished essentially by lead content. The market standard remains OT58/CW617N, with around 2% lead to ensure machinability. With the EU limit dropping towards 5 µg/L by 2036, some manufacturers are qualifying alternatives such as dezincification-resistant brass (DZR), which keeps lead for machinability but resists dezincification thanks to arsenic, and silicon-based low-lead alloys, which also drastically reduce lead.
CW617N
The alloy we find on most of the hydrosanitary fittings that come in to us. The lead is there for machinability: without it, brass is difficult to drill and thread at industrial cost levels.
CW602N
Keeps a lead content similar to OT58 (~2%), but a small addition of arsenic (0.08-0.15%) inhibits dezincification. Already required in some markets with stricter rules on aggressive waters (Germany, United Kingdom, France).
es. CuZn21Si3P
Silicon (≈3%) replaces lead as the machinability enabler and also provides dezincification resistance. The first manufacturers are testing it ahead of the 2036 EU 5 µg/L limit. Treated in pre-series volumes for clients who want to be ready.
08 / Frequently asked questions
Geometries with deep internal cavities require a specific approach. On these components, internal coverage depends on the circulation of the electrolyte inside the cavity during the electrolytic phase. We process these parts exclusively on the static rack, with orientations studied for each geometry.
Drawing (.dwg / .step / .pdf), starting alloy, expected volumes. Pre-series in 5-10 working days.
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