Sampling of Lead in Drinking Water

Sampling of lead in drinking water has to include contributions from all soimces and factors influencing the lead concentrations at the tap. Therefore, various sampling techniques with different purposes have been developed and routinely applied. These are listed in the next section. 

Hayes, C.R. (2009). Computational modelling to investigate the sampling of lead in drinking water. Water Research 43, 2647-2656. 

In the Slovak Republic in 1996 the median concentration of lead in drinking water was 2.6 p.g/1. None of the 235 samples exceeded the limit value for lead (Food Research Institute, 1997). In 1998 the national limit value for lead concentration in drinking water was lowered from 50 to 10 p.g/1 (Anon, 1998). 

It should be noted here that the Member States failed to agree a harmonised monitoring method. In consequence, some EU countries have either not sampled for lead in drinking water at all or have used inappropriate sampling methods. Further, the vague requirements of Article 6(3) have largely been overlooked, as have the requirements of Note 4 to Part B of Annex 1. 

The definition of inventory monitoring is the monitoring to estimate the lead problem in a water supply zone or country. To support the implementation of the Protocol on Water and Health, the guidelines for the sampling and monitoring of lead in drinking water (Hoekstra et al., 2009) recommend surveys based on random daytime sampling with the sample numbers in each water supply system surveyed as shown in Table 3.3. 

Provide a deeper insight into the behavioural characteristics of the stagnation sampling methods used in the regulation of lead in drinking water. 

Plumbosolvency characteristics also strongly influence the results of sampling for lead in drinking water and can be... 

There is scope to improve the various sampling protocols that are used in the regulation of lead in drinking water in both Canada and the United States. Computational modelling tools can greatly assist the development of robust sampling protocols via exhaustive behavioural assessment. 

In a more recent Lederal Register notice (EPA 1991d), EPA examined the occurrences of lead in source water and distributed water. By resampling at the entry point to the distribution system, few samples were found to contain lead at levels above 5 pg/L. EPA now estimates that approximately 600 groundwater systems may have water leaving the treatment plant with lead levels above 5 pg/L. Based on several data sets, it is estimated that less than 1% of the public water systems in the United States have water entering the distribution system with lead levels above 5 pg/L. These systems are estimated to serve less than 3% of the population that receives drinking water from public systems (EPA 199 Id). 

Guidelines for benchmarking problems with lead in drinking water have been prepared by COST Action 637 in liaison with the EC Joint Research Centre and the World Health Organization (Hoekstra et ai, 2009). These guidelines are based on risk assessment to identify a representative number of water supply areas that are then surveyed by random daytime sampling to determine priorities for corrective action (see Chapters 3 and 6). 

Further evidence of the potential scale of problems with lead in drinking water can be inferred from the pan-European study on lead monitoring reported by van den Hoven et al. (1999) that involved France, Germany, the Netherlands, Portugal and the UK. Split-flow composite (COMP) sampling was undertaken... 

In the guidance (Hoekstra et al., 2009) provided to the Parties to the Protocol on Water and Health on sampling and monitoring lead in drinking water, it was proposed that the results from RDT sampling surveys should initiate the different grades of response shown in Table 6.1. 

Table 6.6 Zonal failure rates for lead In drinking water In 45 UK zones, based on RDT sampling and exceedance of 10 rg/l, prior to orthophosphate dosing...

At the zonal level, risk from lead in drinking water can be defined by compliance with the WHO guideline value of 10 p,g on the basis of random daytime sampling. 

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