Borewell Pump Size Guide: V3, V4, V4 Slim, V5 and V6 Explained

Choosing a borewell pump starts with your bore's inside diameter, because the pump and its cable must slide down the casing freely. As a rule of thumb, a V3 (73 mm) suits narrow bores, the V4 Slim (82 mm) is built for 4½-inch bores, a V4 (96 mm) is the usual choice for 5- to 7-inch domestic bores, and V5 (125 mm) and V6 (142 mm) pumps go into larger bores, from about 6 inches for a V5 and 6½ inches for a V6, where more water is needed. Once the diameter fits, you match the pump to depth, water level and bore yield.

What do V3, V4, V5 and V6 mean?

In India, borewell submersible pumps are grouped by size class. The number after "V" is a nominal size class in inches and gives a rough idea of the bore the pump is meant for, though in practice the bore needs to be somewhat wider than that number. It is not the horsepower, and it is not the exact pump diameter, so always check the actual outer diameter of the pump-motor set.

Here is how the Arrot-z borewell range compares (see the full product range):

Step 1: Match the pump to your bore diameter

The bore must be comfortably wider than the pump. The flat cable runs alongside the pump, and borewells are rarely perfectly straight. A pump stuck halfway down can be very difficult and expensive to recover.

These are typical figures, not a guarantee. Around Hyderabad and across much of Telangana, many newer bores are drilled at about 6 to 6½ inches, while some older bores are 4½ inches, where a standard 96 mm V4 can be a tight fit and the V4 Slim leaves more clearance. Check your drilling record for the actual casing size, and let the installer confirm it before lowering the pump.

Step 2: Know your depth and water level

Depth and water level tell you how hard the pump must work. Note down:

• Total bore depth, from your drilling record.
• Static water level, where water stands when the pump is off.
• Pumping water level, where the water settles while the pump runs. This is what matters for head.
• Seasonal drop. In Telangana, water tables can fall sharply in April to June compared with the months after the monsoon.

As a general practice, the pump is set below the lowest expected pumping water level with some margin, but kept a few metres above the bottom of the bore so it does not draw in silt and sand.

The total head is roughly the vertical lift from the pumping water level to the highest delivery point (such as an overhead tank), plus friction losses in pipes and fittings. Our guide on how to calculate pump head, flow and HP walks through this step by step.

Step 3: Match flow to bore yield

Every bore can only give so much water per hour. If the pump draws more than the bore yields, the water level falls to the pump, it runs dry and the motor overheats. Over-pumping can also pull sand into the bore.

• Get the yield from your driller's test, or note how long the pump runs before flow drops.
• Pick a pump whose flow at your working head is at or below the bore yield.
• In weak bores, a smaller pump running longer usually beats a big pump that runs dry.

Radial flow vs mixed flow

• Radial flow impellers develop more head per stage at moderate flow. They suit deep bores and tall delivery heights.
• Mixed flow impellers move more water at moderate head. They suit high-yield agricultural bores feeding fields, drip or sprinkler systems.

The V4, V5 and V6 are available in both types; the V3 and V4 Slim are radial flow.

Step 4: Check your power supply

Smaller domestic borewell pumps are commonly available for single phase (220–230V) supply, while larger agricultural pumps usually need three phase (415V) supply. Read our comparison of single phase vs three phase water pumps before deciding.

Also plan for voltage fluctuation, which is common on rural feeders. A proper control panel with overload and dry-run protection protects the motor, and the cable must be sized for the depth, because long runs of thin cable cause voltage drop at the motor.

Step 5: Consider build and materials

• Copper rotor: all Arrot-z borewell models use a copper rotor. Copper conducts better than aluminium, which generally means lower losses and less heat in the motor.
• Stainless steel: the V4 is available in stainless steel, a sensible option where water is hard, saline or corrosive.
• S-S / K types: the V5 and V6 are offered in S-S and K variants. Share your bore details and application, and the team can explain which variant suits you.

Quick selection examples

Illustrative starting points, not a final selection:

• House in Hyderabad, 6½-inch bore, filling an overhead tank: usually a V4.
• Older 4½-inch bore: V4 Slim.
• Farm with a 7- or 8-inch high-yield bore feeding drip or sprinklers: V5 or V6, often mixed flow. See our agricultural irrigation pump guide.

Common sizing mistakes to avoid

1. Buying the biggest pump the bore can take, instead of what the bore can yield.
2. Sizing for the post-monsoon water level and getting caught out in summer.
3. Setting the pump too close to the bottom of the bore.
4. Skipping protection devices to save a little money upfront.

Need help choosing the right size?

Call +91-7799794047 or +91-9790854516. Keep your bore diameter, depth, water level, approximate yield, delivery height and power supply handy, and the Aqua Pump Engineer team will suggest a suitable Arrot-z borewell pump.