Safe and clean water, one of the vital basic needs for all living beings, becomes scares in many parts of the world due to various reasons. Groundwater is the main water source for drinking and other domestic purposes in most parts of the eastern, coastal belt of Sri Lanka. High population density along with lack of proper drainage systems and improper excreta disposal methods in the sandy soils are some factors directly affect the shallow aquifers, and hence, indirectly on health. In addition to these chronic undesired factors, acute natural disasters like tsunami, cyclones and flood too are aggravating the conditions. The outcomes of secondary data collected and GW quality (Field and Lab) studies are reported. Insufficient dwelling area (< 40 m2) per ave. family of 5 members, high densities of septic tanks (5,432/ km2) and dug wells (4,428/km2) are some of the highly probable reasons for the water related diseases (diarrhoea, typhoid and other intestinal infectious diseases) mostly reported in that area. 2004 Tsunami had a very high impact on those areas both to human lives and infrastructure, aggravated the existing problems on water, sanitation and health.