Most widely used type of tube well in India: Which type of tube well is considered the most important and widely used for Indian alluvial aquifers?

Introduction / Context:
In alluvial formations common across large parts of India, tube wells are constructed to tap unconfined or confined aquifers of sand and gravel. The intake section design (screen/strainer) governs entrance losses, sand pumping, and longevity. Among the historical and widely cited types is the “strainer well,” used extensively in practice and examinations.

Given Data / Assumptions:

• Alluvial aquifer with significant sand content.
• Standard well construction using a screen/strainer to admit water and exclude sand.
• Focus on commonly adopted, textbook-cited type.

Concept / Approach:
Strainer wells employ metal or PVC strainers with slots or wire-wound screens in the intake zone opposite water-bearing layers. Proper slot size selection and gravel packing (if applied) control sand entry. Legacy terminology in Indian water-resources texts frequently labels such installations “strainer wells,” reflecting their prevalence.

Step-by-Step Solution:
Identify the most common intake arrangement for alluvial formations.Relate to standard practice: strainer/screen opposite aquifer layers.Select “Strainer well.”

Verification / Alternative check:
State groundwater departments and numerous case studies describe strainer-screened tube wells as the default method in alluvial belts, supporting the choice.

Why Other Options Are Wrong:

• Cavity wells: suited to clayey formations; not the primary alluvial solution.
• Slotted/perforated pipe: generic terms; without proper strainer design, sand exclusion is poor.
• Gravel-packed well: a construction detail that can also be used with strainer screens but is not the historical “type” referenced by the question.

Common Pitfalls:

• Selecting a generic term instead of the established nomenclature in Indian textbooks.
• Ignoring slot size and grading, which are critical to performance.

Final Answer:
Strainer well