What You'll Need Before You Start

A successful submersible pump installation begins with preparation. Gather the following before you begin:

  • Submersible pump sized correctly for your well or sump
  • Drop pipe (HDPE or stainless steel — avoid galvanised in potable water systems)
  • Safety rope or stainless steel safety cable
  • Electrical cable of correct gauge for the pump's amperage and depth
  • Waterproof cable splice kit (if joining cables)
  • Pipe clamps, check valve, and pressure tank (for water supply applications)
  • Multimeter, pipe wrenches, and cable ties

Step 1: Check the Well or Sump Dimensions

Measure the inner diameter of your well casing or sump pit. Your pump's outer diameter must be smaller — typically by at least 25 mm — to allow free water intake and prevent heat build-up. Also check the static and dynamic water levels to confirm the pump will always remain submerged during operation.

Step 2: Prepare the Pump Assembly

Attach the drop pipe to the pump's discharge outlet, wrapping threads with PTFE tape for a watertight seal. Install a check valve about 1–2 metres above the pump to prevent backflow and water hammer when the pump stops. Secure the electrical cable to the drop pipe using cable ties every 3 metres — never let it hang loose.

Step 3: Lower the Pump into the Well

This step requires care, especially in deeper installations. Attach the safety rope to the pump's lifting eye — this is your backup if the pipe joint fails. Lower the pump slowly, adding pipe sections as you go. Never let the pump rest on the bottom of the well; maintain a clearance of at least 1–2 metres above the sediment layer to avoid drawing in debris.

Step 4: Make the Electrical Connections

Before any wiring, switch off the power at the breaker. Submersible pumps typically require:

  1. A dedicated circuit with appropriate overcurrent protection (check the pump's nameplate).
  2. A control box (for two-wire and three-wire single-phase motors) or a starter (for three-phase motors).
  3. A pressure switch wired in line to start/stop the pump automatically.

Use a waterproof splice kit for any underground or wet-area cable joins. Test insulation resistance with a multimeter before energising.

Step 5: Connect the Surface Pipework

Connect the rising main to a pressure tank and distribution pipework. Install an isolation valve above ground level for easy maintenance. For potable water, fit an approved backflow preventer to protect the supply.

Step 6: Test and Commission

Before running the pump continuously:

  • Run the pump briefly and check for correct flow and pressure.
  • Listen for unusual noise, which may indicate cavitation or a misaligned installation.
  • Check the motor current draw with a clamp meter — it should be within the nameplate rating.
  • Verify that the pressure switch cycles the pump on and off correctly.

Common Installation Mistakes to Avoid

  • Undersized cable — causes voltage drop, overheating, and premature motor failure.
  • No check valve — leads to water hammer and repeated cycling.
  • Pump resting on the bottom — draws in sediment and blocks the impeller.
  • Incorrect pump depth — pump running dry destroys the motor within minutes.

Follow these steps carefully, and your submersible pump will provide reliable service for many years.