Lead in Drinking Water

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Lead in Drinking Water National Water
Summit October 2008
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What is lead?

• Lead (Pb) is a dense, relatively soft,
  malleable metal
• Low Tensile Strength
• Relatively Easy to smelt
• Widely available

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Uses of Lead

• Used for thousands of years in building
  industry
• Weights, lead-acid batteries, shot
• Part of solder, pewter and fusible alloys

• In UK estimated 40 of properties supplied via
  lead piping
• In Ireland distribution lead main has
  generally been replaced with
  plastic and ductile iron piping
• Since c.1970, services pipes tend to be copper
  or plastic

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Possible Health Effects caused by high lead levels

• Lead is a cumulative toxin no immunity
• Repeated exposure causes amounts to accumulate
  in the body

• Physiological damage
• Effects Central and peripheral nervous systems
• Gastrointestinal tract
• Kidney
• Haematological system

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Plumbosolvency

• The ability of a solvent, notably water, to
  dissolve lead

• More common in older pipes
• ? water attacks lead pipes and lead solder
• Some private plumbing systems still contain
  lead piping
• ? especially the service pipe from stopcock
  to house
• This is the greatest source of
  plumbosolvency

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Factors which affect dissolution of lead

• Alkalinity
• Temperature
• Contact Time

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How does lead present?

• Particulate Lead
• ? lead flaking from old pipes
• Dissolved Lead
• ? dissolution of lead corrosion products
• - lead carbonates on the pipewall

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What are the Parametric Limits?

• From S.I. No.278 of 2007 (Drinking Water
  Regulations)
• ? Until 24 Dec 2013 25 micrograms / litre
• ? From 25 Dec 2013 10 micrograms / litre

• All appropriate measures shall be taken to
  reduce concentrationsduring the period

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Control of Plumbosolvency

• Medium Term Solutions
• ? pH correction (to above 8.0)
• ? Adequate Organics removal
• ? eliminate significant iron discolouration
  from networks
• ? Orthophosphate Dosing (c.95 of UK dosed)
• - Formation of insoluble layer of lead
  phosphate
• - Typical initial dose rate of 1-1.5mg/l,
  after to 1mg/l
• - May take up to one year for layer to form

• Long-term
• ? Replacement of public mains
• ? Possibly provide once-off grant to
  householders?

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What can Local Authorities do before 2013?

• Determine extent of lead piping (public and
  private)
• Build up a database of sampling results
• Feed data into CIS or infoWorks
• Identify areas with high levels and consider
  medium-term solution
• Investigate and develop a programme to replace
  pipes

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Lead in Drinking Water National Water
Summit October 2008