Ef Chlor (NaDCC) - Portable Water Purification Tablets (30 Tablets Per Pack, Each Tablet Purifies 5 liters contaminated water or 10 liters clear water) Used by disaster relief agencies world-wide Portable, great for camping and hiking effervescent additive reduces chlorine taste. Ready to drink in 30 minutes. Safe (cannot overdose) Eliminates need for boiling water or rotating stored water.