How much alum is needed for 1000 ltr of water for purification?

The amount of alum needed for water purification typically ranges from 10 to 50 grams per 1000 liters of water, depending on the water quality and turbidity. For most applications, starting with around 20 grams is common, and adjustments can be made based on the specific conditions and results observed. It's essential to conduct tests to determine the optimal dosage for effective purification.