HEALTH EFFECTS OF INORGANIC COMPOUNDS IN DRINKING WATER (EET 4156CD)
SAMPLING FOR HOUSEHOLD WATER-LEAD Final Report to the Department of
Report No DWI0276
None of the existing guidelines or standards for lead in drinking water adequately specifies the method of sampling that should be used for monitoring the concentration of lead at the consumer's tap. A similar, though less important, question of sampling arises for other water contaminants derived from pipe systems.
Project 4156 had the objective of developing a reliable, practicable and economical method of assessing the mean intake of metals derived from plumbing systems by typical inhabitants of a particular house or water supply zone. This objective embraced several metals but particular emphasis was to be given to lead.
The work undertaken comprised the gathering of information to provide the justification for recommendations. Surveys were undertaken of water-use patterns and of stagnation curves for lead, which have been separately reported elsewhere. The present report welds this information together in order to demonstrate the operating characteristics of different types of sample. The main method considered is that of sampling after a fixed time of stagnation (FTS).
FTS is recommended as the most suitable method of assessing the mean concentration of lead in water that would be consumed by members of a typical household. A stagnation time of 30 minutes would be a reasonable time to choose and would enable the concentration in the sample to be directly interpreted as an estimate of the mean lead concentration in water used for drinking and cooking. The reasons and assumptions on which this advice is based are set out and discussed.Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.