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Screening of Heavy Metals in Drinking Water from Hot Water Systems in Germany COST Action 637 2nd Int. Conference Lisbon (29 - 31 October 2008) Achim Ruebel email@example.com
Overview • Motivation • Domestic distribution system of hot water -Focus on central supply • Screening of heavy metals in hot water • Results and discussion
Motivation • Monitoring programmes on heavy metals in domestic distribution systems are designed for cold water • Hot water is frequently used for human consumption • Does chemical hot water quality differ from cold water quality? • No data on heavy metals in drinking hot water available
Hot water – Focus on central supply • Central supply for drinking hot water • hot water cylinder (200 – 1000 L) • two pipe systems: hot water and cold water system • circulation system • pumps, mixing devices etc. • Peripheral devices for hot water supply (near tap) • instantaneous water heater • small water heater (under or oversink) etc. Factors affecting hot water quality • operating conditions (e.g. temperature, stagnation, circulation) • materials, fixtures and fittings
Domestic distribution system- cold and hot water Shower head Tap Central supply for drinking hot water Cold water system Circulation system Hot water cylinder
Cold water Mixed water Hot water Circulation Mixer Circulation system for drinking hot water
Methods - Hot water screening • Sampling area: Germany, North Rhine-Westphalia • Sampling sites: Domestic distribution systems of public buildings provided with central supply for drinking hot water • Sampling point: taps, shower heads, valves of the circulation hot water system • Sampling method: Random day time sampling of hot water (1 L, no flush) • Analytical method: ICP-OES (ISO 11885) Screening of 20 elements: Pb, Cd, Cr, Cu, Co, Ni, Fe, Mn, Zn, Mo, Si, Al, P, B, alkali/earthalkaline metals
Screening data - hot water samples from domestic supply systems Pb limit value 0,01 mg/l Random day time sampling; IWW, Germany (11,8) 38 premises
Cold water Random day time sampling; Public health authorities, Germany Sequential sampling procedure; IWW, Germany Hot water quality vs. cold water quality Hot water Random day time sampling; IWW, Germany (11,8) Pb limit value 0,01 mg/l
Discussion (1) • Chemical hot water quality similar to cold water quality • Major problem: lead, nickel, iron non-compliance up to 10 % of water samples • Minor problem: copper • No problem: cadmium • Further investigation on chemical hot water quality required?
Discussion (2) • Focus on Nickel? How can we reduce the release of nickel from taps?