Ef Chlor (NaDCC) &ndash; Portable Water Purification Tablets - BULK PACK OF 100 STRIPS [1000 TABLETS] - Each Tablet Purifies 6.6 GALLONS Used by disaster relief agencies world-wide and approved by World Health Organization. Red Cross recommends chlorine over all other purification methods. NaDCC tablets contain 60% chlorine with an effervescent additive that reduces chlorine taste and makes the product safe from possible overdose. (Chlorine dissapates in 30 minutes) Use only just before drinking. Purifies 6.6 gallons contaminated water or 13 gallons clear water per tablet. Kills 100% of bacteria and all known viruses. Eliminates need to boil water or rotate stored water.