Agencies Lead Cadmium Chromium Arsenic Zinc ISI 0.1 0.01 0.05 0.05 5.0 WHO 0.05 0.005 - 0.05 5.0 USEPA - 0.005 0.1 0.05 - CPCB NR NR NR NR 15

*: No Relaxation

Table 1: Permissible limits of heavy metals by different agencies (ppm) in drinking water.