Toxic heavy metals get into humans through absorption, inhalation and ingestion. All heavy metals are toxic to animals and plants when present in excessive amounts. The adverse effects of heavy metals in mammals may manifest in disorders such as growth retardation, decrease in longevity, changes in reproductive cycles, chronic diseases and formation of tumours. River Nyamindi flows from Mt. Kenya Forest passing through rocks, soil, agricultural land, residential areas and urban centres. Geological factors and human activities may have made heavy metals get into the river water. Since the water is used for domestic purposes and irrigation, it was necessary to determine if heavy metal concentration in river Nyamindi has reached alarming levels. Water and sediment samples were collected along river Nyamindi during wet and dry season. The samples were digested appropriately and the concentration of eight heavy metals determined using ICP-MS. The mean amount of Cd, Cr, Ni, Pb, Zn, As, Mn and Se in sediment were 0.0882, 41.1219, 91.7718, 10.7445, 54.3880, 2.4561, 1753.5587 and 5.7648 mg/kg respectively during wet season and 0.0590, 39.1176, 559.0917, 0.3781,76.3715, 3.0114, 1714.4195 and 6.5488 mg/kg respectively during dry season. The mean concentration of the same metals in water was 0.00005, 0.0167, 0.1943, 0.0223, below detection limit (BDL), 0.0002, 0.1379 and BDL ppm respectively during wet season and 0.0009, 0.0005, 0.0148, 0.0184, BDL, 0.00003, 0.0080 and 0.00003 ppm respectively during dry season. The mean amount of Cr, Ni and Mn in sediment were found to be above WHO and US EPA permissible limits during both seasons. The mean concentration of Cr and Mn in water were above WHO and KEBS/WASREB permissible limits during wet season. However, during dry season, all the eight heavy metal concentrations in water were below WHO, KEBS/WASREB permissible limits. Therefore, as far as the eight heavy metals are concerned, water from river Nyamindi was not be potable during rainy season but was potable during dry season. However, further investigations should be carried out to determine other water parameters to confirm it’s suitability as potable water.