How to Choose the Right Water Well Screen Size and Material for Your Borewell Choosing the right water well screen is one of the most important steps when constructing a borewell. A well-designed screen ensures efficient water flow, prevents sand and sediment from entering the well, and extends the life of your pumping system. In the United States, where groundwater systems vary widely depending on soil type and region, selecting the appropriate screen size and material is vital for both residential and agricultural wells. Let’s explore how to make the right choice.
Understanding the Purpose of a Well Screen A water well screen acts as a filter between the aquifer and the well casing. Its main function is to allow water to enter the well while keeping out sediment, sand, and other debris that could damage your pump or clog your system. The screen’s slot size, open area, and material all influence how efficiently water flows into your well and how long the system lasts.
Factors to Consider When Choosing Screen Size Selecting the proper screen size depends heavily on the characteristics of the formation you’re drilling into. In the U.S., borewells are often drilled in formations ranging from fine sand to gravel. 1. Grain Size Analysis: Before deciding, a grain size analysis should be performed on the aquifer material. This test helps determine the ideal slot size that will retain 90% of the sand while allowing maximum water flow. 2. Common Slot Sizes: Fine sand formations: 0.010–0.020 inches Medium sand formations: 0.020–0.030 inches Coarse sand or gravel formations: 0.030–0.060 inches Using a screen that’s too small will restrict water flow, while one that’s too large will allow sand to enter the well, causing wear and tear on your pump.
3. Screen Length and Open Area: Longer screens with greater open area allow for higher water yield and lower entrance velocity, reducing the potential for clogging. A good rule of thumb is to keep the entrance velocity under 0.1 ft/sec to ensure efficient operation.
Choosing the Right Material The choice of material is just as critical as the screen size. The environment, water chemistry, and maintenance preferences all affect which material performs best.
Stainless Steel: Stainless steel is one of the most popular choices in the U.S. due to its durability, corrosion resistance, and longevity. It’s ideal for areas with aggressive water conditions or high levels of dissolved solids. Though more expensive upfront, stainless-steel screens often pay off in reduced maintenance and longer service life. PVC (Plastic): PVC screens are lightweight, corrosion-resistant, and cost-effective. They are suitable for domestic wells with non-corrosive groundwater. However, PVC may not be the best option for high-temperature or chemically aggressive environments. Carbon Steel: Carbon steel screens are economical but prone to rust and corrosion over time. They are generally used for temporary installations or in areas where water chemistry is neutral and non-corrosive. Johnson-Type (Wedge Wire) Screens: Increasingly popular across the U.S., these Vshaped wire screens are known for their high open area and excellent non-clogging performance. They can be customized in both stainless steel and PVC materials, making them versatile for different soil types.
Regional Considerations in the U.S. 1. Western States (California, Arizona, Nevada): Typically require corrosion-resistant materials due to high salinity and mineral content in groundwater. Stainless steel wedge wire screens are a top choice here. 2. Midwestern States (Nebraska, Kansas, Oklahoma): Wells often encounter sandy and silty formations, so selecting the right slot size (around 0.020 inches) is crucial. 3. Eastern States (Pennsylvania, New York, North Carolina): Wells in these regions may face varying geology; PVC screens often work well for shallow domestic wells.
Conclusion
Choosing the right water well screen size and material for your borewell is a decision that directly affects your water quality, well lifespan, and maintenance costs. Always base your decision on grain size analysis, water chemistry, and local geological conditions. For most U.S. homeowners and contractors, stainless steel or PVC screens with the appropriate slot size offer the best performance and longevity. A properly selected well screen doesn’t just keep your water clean—it keeps your system running efficiently for decades.
