S1.2.3.2 Undertake regular Monthly tank E. coli is Instigate (annual) cleaning inspection. detected in inspection and Accumulation of of tank. 100 ml sample. cleaning sediment in programme. tank. Use two storage quality. Dead animals tanks, the first in tank. Install a second feeding into the tank. Mesh/grills second, and draw disturbed by water from the animals to get second (this access. reduces sediment Unpleasant being carried taste and through into the odour. reticulation). Water turbid. S1.2.3.3 Ensure the Taste. Plastic taste. Reduce tank material chosen size for faster Water stagnant Sample for Di for the tank is turnaround of in plastic tank phthalates suitable for water. for too long. (plasticisers). phthalate drinking-water Flush tank a purposes. is more then number of times Locate tank in a 50% of its on first filling. shaded area. MAV2. Relocate tank to Position into area that is the tank near the cooler. bottom to ensure Relocate inlet to good mixing and tank. avoid stagnant zones near the tank bottom. S1.2.3.4 Line the tank. pH. pH above the Add sodium guideline bicarbonate Dissolution of Increase buffering range (7.08.5). until pH reaches lime from new capacity of the an acceptable concrete tank (eg, addition level. (this problem of sodium should reduce bicarbonate). as the tank ages). Event: CONTAMINATION OF THE WATER WHILE IN THE STORAGE TANK cont’d S1.2.3.5 Restrict access to Regular Evidence of Fence tank, or tanks (fences, inspection of unauthorised provide lockable Vandalism/ locked hatches). tanks for access having hatches. sabotage. evidence of been gained to unauthorised the tank. access. Event: VOLCANIC ASH FALL ON ROOF2 Possible hazards: Arsenic, fluoride, and metals. Level of risk: Low
S1.2.3.2 Accumulation of sediment in tank. Undertake regular (annual) cleaning of tank. Use two storage tanks, the first feeding into the second, and draw water from the second (this reduces sediment being carried through into the reticulation). Monthly tank inspection. quality. E. coli is detected in 100 ml sample. Dead animals in tank. Mesh/grills disturbed by animals to get access. Unpleasant taste and odour. Water turbid. Instigate inspection and cleaning programme. Install a second tank. S1.2.3.3 Water stagnant in plastic tank for too long. Ensure the material chosen for the tank is suitable for drinking-water purposes. Locate tank in a shaded area. Position into the tank near the bottom to ensure good mixing and avoid stagnant zones near the tank bottom. Taste. Sample for phthalates (plasticisers). Plastic taste. Di phthalate is more then 50% of its MAV2. Reduce tank size for faster turnaround of water. Flush tank a number of times on first filling. Relocate tank to area that is cooler. Relocate inlet to tank. S1.2.3.4 Dissolution of lime from new concrete tank (this problem should reduce as the tank ages). Line the tank. Increase buffering capacity of the (eg, addition of sodium bicarbonate). pH. pH above the guideline range (7.08.5). Add sodium bicarbonate until pH reaches an acceptable level. Event: CONTAMINATION OF THE WATER WHILE IN THE STORAGE TANK cont’d S1.2.3.5 Vandalism/ sabotage. Restrict access to tanks (fences, locked hatches). Regular inspection of tanks for evidence of unauthorised access. Evidence of unauthorised access having been gained to the tank. Fence tank, or provide lockable hatches. Event: VOLCANIC ASH FALL ON ROOF2 Possible hazards: Arsenic, fluoride, and metals. Level of risk: Low
source-roof-catchments-feb14-v2.docx