Abstract:
Changes in land use pattern, improper techniques in water treatment process, and changes in the
rate of application of agrochemicals and fertilizers have significant impacts on the treated and raw
water quality. Therefore, qualitative and quantitative assessments of water quality are required from
catchment to consumer to develop sustainable water management procedures, and this can be
implemented by “Water Safety Plans” as its primary objective is to ensure drinking water quality
from catchment to consumer through a comprehensive risk assessment and risk management
procedure. The Bangalawady water treatment plant located in Sammanthurai, at about 13 km away
from Ampara town was selected for this study to develop “Water Safety Plan” since it produces
10000 m3 /day of potable water and treated water is distributed to 1800 households who are living
nearby areas, namely Sammanthurai, Kalmunai, Sori Kalmunai and Veeramunai. Intake of this
treatment plant is located at Weeragoda, 9 km away from treatment plant. This plant is responsible
for operating intake, water treatment plant, storage tanks and distribution systems. The treatment
processes consist of screening, pre-chlorination, aeration, coagulation and flocculation,
sedimentation, filtration with air and water backwashing system and post chlorination. Possible
hazardous events were identified from catchment to consumer by questionnaire surveys, field visits
and laboratory tests. A risk matrix was developed to identify the severity of residual risks by
assigning rating based on likelihood and severity of hazardous events and existing control measures.
Based on the ratings, an improvement plan was drawn up to suggest corrective actions to minimize
the residual risks by modifying or repairing components of the water supply system.
