Assessing rainwater quality in Ca Mau Province: Unveiling the potential and viability for domestic usage

Abstract

The potential for exploiting rainwater in Ca Mau Province is immense due to its average annual rainfall of 1772 to 2500mm. Over a 15-year continuous monitoring period, the analysis of rainwater quality in Ca Mau Province reveals a prevailing alkaline tendency, with an average pH of 5.90, well within the established raw water quality standards. Concurrently, ongoing groundwater exploitation activities pose a significant threat to the natural aquifer reserves in the region. Recognizing this challenge, rainwater harvesting emerges as a pivotal strategy to alleviate the strain on groundwater extraction. The accumulation of freshwater during the rainy season in Ca Mau, facilitated by household rainwater storage tanks, offers a sustainable solution, ensuring a readily available supply for drinking and cooking needs during the dry season when rainfall is scarce. In addition, average tank capacity to meet the domestic water demand of a 5-member household is 10m3 for the whole year while this number increases to 18 20m3 during the dry years. These rainwater stored in tanks should be treated with chlorine or UV rays before use. Our study provides valuable evidence for policy makers and managers, based on the case study at Ca Mau, to develop a sustainable rainwater management plan for improving the livelihoods of millions people lacking freshwater in coastal zones of the Vietnamese Mekong Delta.