Physico-chemical Quality of Harvested Rainwater from Some Settlements in Uyo, Nigeria

The use of harvested rainwater for domestic purposes is on the increase in Nigeria, as public water is inadequate as a result of population increase. This study sought to determine the quality of harvested rainwater from some settlements in Uyo, Nigeria, and assess the suitability of the water for domestic household use. Harvested rainwater samples were collected from selected household tanks at Ikot Ntuen Oku, Afaha Oku, Ikot Oku, Mbiabong and Ifa Atai areas of Uyo. Analyses for physico-chemical parameters including pH, electrical conductivity, total dissolved solids, turbidity, total hardness, total alkalinity and acidity, dissolved oxygen, total suspended solids, were done using standard APHA methods. Trace metals were measured using atomic absorption spectrophotometric techniques. The physicochemical parameters measured were below the WHO limits for portability except for dissolved oxygen. The pH values recorded ranged from 5.54 to 6.38 with an overall mean of 5.90; TDS levels ranged from 9.68 to 15.02 mg/l with an average value of 11.8 mg/l while the turbidity values ranged from 2.3 to 3.8NTU. For the nutrients, nitrate levels ranged from 0.97 to 2.1 mg/l with a mean of 1.55 mg/l while the chloride levels ranged between 2.12 and 4.42 mg/l with a mean value of 3.65 mg/l. Levels of trace metals were within WHO recommended limits except for Fe, Cd, and Cu. Some of the results indicated that Cr level was 0.001 mg/l for all sampling points while Zn levels ranged from 1.04 to 1.75 mg/l with a mean value of 1.44 mg/l. Correlation studies showed that Fe was from natural sources while Cr, Mn, Cu, Zn and Cd were from anthropogenic sources. These results indicated expected adverse effects from the consumption of the harvested rainwater with respect to Fe, Cd and Cu. Appropriate treatment of the rainwater to improve quality before use is recommended. This will help improve the water quality and provide portable water for households in the communities.