Aluminium and heavy metals in potable waters of the north Ceredigion area, mid-Wales

Routine monitoring of the public water supply in Aberystwyth revealed high levels of aluminium during November 1989. These levels were twelve times the EEC recommended level and three times the maximum permitted level. While the reservoirs supplying the region and the streams draining their upland peaty catchment areas generally contain moderate levels of Al, Al salts added as coagulating agents are a major source. There is also considerable variation of the Al in potable waters through the month of November 1989 for an Aberystwyth supply. Private supplies, from groundwaters, in the region generally contain low Al. While most drinking waters in the region contain low Pb, values close to the EEC limit have been recorded for some samples from older houses with Pb pipes, while a sample from a well supply in an old lead mining area contained three times the EEC limit. Despite the wide use of Cu piping for water supplies in the area, most values for this element in mains-water are low, with occasional higher values. However, many private supplies from spring sources are extremely Cu-rich and again levels of this element in a private supply showed a marked temporal variation during November 1989. Zinc levels in potable waters of the area are very variable. That most of the Zn in potable waters is derived from the dissolution of Cu pipes is evidenced by a strong correlation between Cu and Zn in these waters. A few Cd values of over 2 μg L^-1 have also been recorded.