WATER SAFETY
says they will. The reality of healthcare water chemistry is less obliging. The fundamental issue is
leaching. Lead in brass is not bound; it is dispersed. Traditional formulations such as CW617N contain between 1.6 and 2.5 per cent lead by mass, added during manufacture to improve machinability. In a static, neutral-pH system, that lead stays put. In a hospital system, conditions are rarely either static or neutral. Stagnation is the first
driver, and it is endemic in healthcare estates with redundant pipework and intermittently used outlets. Chemical dosing compounds the problem: chlorine dioxide and copper-silver ionisation both alter pH and accelerate corrosion. Then there is dezincification, the selective leaching of zinc from
DZR brass resists the corrosion that damages conventional brass.
brass that leaves a porous copper structure vulnerable to mechanical failure and increased metal release. Dezincification-resistant brass, designated DZR,
was developed to resolve the latter two points. By adjusting the alloy structure and adding small quantities of arsenic, antimony, or tin to stabilise the alpha phase, DZR brass resists the corrosion mechanism that hollows out conventional brass under sustained water contact. CW602N is the most widely used DZR designation in UK potable water applications, and it is the baseline for any responsible healthcare specification. But DZR alone does not solve the lead problem. The
corrosion-resistance mechanism that protects against dezincification can, in some chemistry conditions, increase the rate at which residual lead leaches into water (VTechWorks). For hospital environments preparing for a 5 µg/L threshold, DZR is necessary but not on its own sufficient. The honest answer for new specification is zero-lead
Ayrton Byng Ayrton Byng is
specification manager at Brymec, an integrated building services systems partner. Working closely with consultants and design teams, he provides technical guidance to support compliant, high-performance piping specifications from the earliest project stages, building strong relationships that help deliver efficient, risk-free MEP designs across the construction industry.
alloy. Low-lead and lead-free DZR formulations are now commercially available, with lead content below 0.25 per cent or eliminated entirely. They meet BS EN 1982 for copper alloy castings and pass ISO 6509 dezincification testing. They are slightly more expensive at the component level, and dramatically cheaper across the asset life.
This is also where stainless steel becomes serious. Stainless press systems, fully welded or compression- fitted into 304 or 316L grades, remove the lead variable from the equation entirely. For augmented care units, paediatric wards, neonatal facilities and theatres, the case for stainless across the wetted path is now compelling. Specifiers need to be reading material certificates against tomorrow’s threshold, not yesterdays.
Pillar 3 n Where lead meets Legionella
There is a connection between lead leaching and Legionella risk that does not get enough airtime. The mechanism that drives one propels the other, and the engineering solution to one is often the engineering solution to both.
Both start with poor hydraulic balance. When a
healthcare water system is unbalanced, certain branches sit at low or zero flow for extended periods. Water in those dead legs stagnates. Stagnation raises temperature in cold runs and lowers it in hot returns, sliding the system into the 20°C to 45°C range that Legionella pneumophila needs to proliferate. The same stagnation gives any lead in contact with that water dramatically more time to leach. One condition leading to two regulatory exposures. HTM 04-01 Part B is explicit about the operational envelope. Hot water must be stored above 60°C, distributed above 55°C, and reach outlets above 50°C within one minute. Cold water must be below 20°C at outlets within two minutes (NHS England). These are not nominal targets. They are the window within which biofilm growth is suppressed and chemical leaching is minimised. The component that holds that envelope together is
the thermostatic balancing valve. A properly specified TBV maintains the hydraulic balance of a return circuit, holds water temperatures across all branches within the HTM 04-01 envelope, and reduces both the dwell time that drives leaching and the temperature window that incubates pathogens. Combine a TBV with a thermostatic mixing valve at the point of use, you have the dual control required by HSE L8 ACoP and HSG274 Part 2 (HSE L8). The implication for material selection is direct. A
system designed to prevent Legionella growth (high flow, balanced returns, controlled dwell times) is also a system that minimises lead leaching. The reverse is also true. A system value-engineered with undersized return pipework and poor commissioning will incubate Legionella and leach lead across the entire asset life. Thermostatic mixing valves and balancing valves on the engineering side, stainless press systems and compression fittings on the distribution side, lead-free brassware accessories at terminal positions and water treatment chemicals matched to the specific chemistry the trust receives. These are not separate procurement decisions. They are a single integrated system, which is why Brymec’s CPD on Drinking Water Hygiene treats Legionella prevention, zero-lead component selection, and TBV specification as one connected discipline.
The deadline that matters for NHS lead compliance is not 2036. It was the day you specified the first component that you intend to leave in a wall beyond 2032.
52 Health Estate Journal September 2026
Pillar 4 n Auditing a live hospital, not an empty one
You cannot audit a working hospital the way you audit a building site. The water cannot be turned off; the wards cannot be decanted. The shutdown windows that make a routine industrial audit possible do not exist in healthcare. The starting point is a documented water safety plan
that goes beyond Legionella. HTM 04-01 Part B already requires a water safety group with defined responsibilities. The same group, the same governance, can absorb lead monitoring with relatively little additional effort, provided
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