system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Minimum depth for the lining of a sanitary well is?
assistant
The correct answer is  The lining of a sanitary well should go down at least 20 feet to ensure that water enters from the bottom and not from the sides of the well. The lining should extend upwards for about 2-3 feet above the ground. Ref: Park's Textbook of Preventive and Social Medicine, 20th edition, p620