Borewell Submersible Pump Selection Guide for Tirupur, Coimbatore and Erode

Most borewell pump failures we see are not caused by a bad pump. They come from a pump that was wrongly sized for the borewell. Before you buy a CRI, Lubi or any other submersible, collect these details.

1. Bore size

The pump must pass freely through the casing. A 4-inch pump needs a bore of at least about 4.5 inches inside diameter. A 6-inch pump usually needs 6.5 to 7 inches. Check your casing size with the driller's record before choosing.

2. Water level, not bore depth

The number that matters is the pumping water level, meaning how deep the water drops when the pump is running. It is not the total depth of the bore. In summer this level can fall a long way in many parts of western Tamil Nadu, so plan for the dry season, not the rainy one.

3. Total head

Total head = pumping water level + height of delivery above ground (for example, up to an overhead tank) + friction losses in the column pipe and delivery line. For a first estimate, add 5 to 10 percent for losses. The pump's performance table must show your required flow at this total head.

4. Flow you actually need

A home filling an overhead tank needs far less flow than a farm running drip or flood irrigation. Ask for a pump that gives the flow you need at your head. Do not buy on HP alone. Two 1.5 HP pumps can perform very differently.

5. Phase, cable and starter

• Use three phase if it is available for anything above about 1.5 HP. It is more efficient and easier on the motor.
• Size the submersible cable for the full length to the starter. Undersized cable causes voltage drop and burnt windings.
• Use a proper starter or control panel with dry-run and overload protection. In areas with power fluctuations, add voltage protection.

6. Installation details

• Use good-quality column pipes and a safety rope.
• Keep the pump a few metres above the bottom of the bore so it does not suck in silt.
• Fit a non-return valve to protect the pump from back-flow.

We supply CRI borewell submersibles as an authorised dealer, and Lubi and Grundfos submersibles as a partner, across Tirupur, Coimbatore, Erode, Salem and Namakkal. Share your bore size, water level and usage, and we will size the pump for you.