The motor is running, the starter shows it ON, but only a thin trickle comes out of the pipe, or nothing at all. This is one of the most dangerous moments for a submersible motor. A submersible motor is cooled by the water flowing past it. When no water flows, it heats up fast, and a motor left running like this can burn within minutes. Here are the 8 usual causes, how to tell them apart, and how a BTCO starter stops the motor before it burns.
Do this first: switch the motor OFF. Don’t leave it running “to see if the water comes”. Then work through the causes below.
Quick check: what do you see?
On a phone, swipe the table sideways.
| What you see | Most likely cause | Go to |
|---|---|---|
| Water came well, then slowed to a trickle after some time | Borewell water level dropped (dry run) | Cause 1 |
| No water at all after the pump was off or repaired | Air lock | Cause 2 |
| Less water than before, slowly over months | Worn pump or choked strainer | Causes 4–5 |
| Motor hums, little water, starter trips | Low voltage or a missing phase | Causes 6–7 |
| Water stops suddenly with a bang or a jerk | Broken pipe or coupling | Cause 3 |
The 8 common causes
1. The borewell water level has dropped below the pump
The most common cause, especially in summer or when the neighbours’ borewells are running. The water level falls below the pump, the pump draws air and the motor runs dry. This is how most borewell motors burn. You will notice water coming with air, in spurts, then slowing after the motor has run for a while. On the starter’s display, the current (amps) drops below normal, because a pump with no water is doing no work.
What to do: a BTCO starter has dry run protection built in. It sees the low current, shows Dry Run Trip and stops the motor, with no sensor needed in the borewell. After the dry restart time you set, it starts the motor again, giving the borewell time to refill. On a weak borewell, a cyclic timer runs the pump ON and OFF in turns so the level can recover. More in protecting your motor when the borewell water goes down in summer.
2. Air lock in the pump
After the pump has stood dry, been pulled out for repair, or run dry for a while, air can get trapped in the pump. The motor turns but the pump can’t push water. Switch off, wait for the water level to settle for 15–30 minutes, and start again. If it happens often, the non-return valve may be leaking (cause 5), so the column drains back every time the motor stops.
3. Broken column pipe, joint or coupling
A cracked column pipe or a loose joint lets water leak back into the borewell before it reaches the top. A broken coupling between the motor and the pump means the motor spins but the pump doesn’t. Signs: water stopped suddenly, the motor sounds lighter, and the current on the display is lower than normal. The pump has to come out to be checked.
4. Worn pump bowls or impellers
Sand in the borewell slowly wears the pump’s impellers. The motor runs normally but the water comes slowly, and gets less month after month. A pump that is too small for the depth (too little head) also gives very little water. Ask your pump mechanic to check the pump, and whether its stages suit your borewell depth. Read how much HP motor your borewell needs.
5. Choked strainer or a stuck non-return valve
The pump’s suction strainer can get choked with mud, scale or roots. A non-return valve that is stuck shut blocks the water; one that is stuck open lets the column drain back. Both mean less or no water at the top. These need the pump pulled out and cleaned.
6. Low voltage
When the voltage is low, the motor turns slower than it should and the pump can’t lift water all the way up, especially from a deep borewell. The motor also pulls more current and heats up. Check the voltage on the starter’s display. BTCO starters trip on current, so when voltage fluctuation pushes the current out of the safe range, the motor is stopped before it burns.
7. A missing phase
If one of the three phases is missing, a 3 phase motor hums, turns weakly and gives little or no water, and it can burn in minutes. Look at the three phase lights on the starter. A BTCO starter stops the motor at once and shows Mains Problem.
8. The delivery side is blocked
Check the obvious things too: a closed valve on the delivery line, a blocked or kinked pipe in the field, or a choked drip filter. The motor runs, but the water has nowhere to go.
How a starter tells you which cause it is
An ordinary starter only switches the motor ON and OFF, so “no water” means guessing. A BTCO starter shows the voltage and current on each phase on its digital display, and that tells you a lot:
- Current lower than normal: the pump isn’t pumping: dry run, air lock, or a broken pipe or coupling.
- Current higher than normal: the motor is struggling: low voltage, a jammed pump, or a missing phase.
- A message on the display (Dry Run Trip, Mains Problem, Overload Trip): the starter has already found the cause and stopped the motor before it burnt. See what each message means.
With the BTCO GSM Module, the trip reason comes straight to your phone, so you know at once when the borewell has run low, without walking to the field.
Never let a motor run without water
Every minute a submersible motor runs with no water flowing past it, it gets hotter. Dry running is one of the top causes of motor burning. A starter with dry run protection is the cheapest way to stop it. Every BTCO starter has it built in, along with single phasing, overload and voltage fluctuation protection.
Not sure which starter your motor needs? Answer a few questions in the starter finder.
Frequently asked questions
Why is my borewell motor running but no water is coming?
The most common reason is that the borewell water level has dropped below the pump, so the pump is drawing air. Other causes are an air lock, a broken column pipe or coupling, a worn pump, a choked strainer or stuck non-return valve, low voltage or a missing phase. Switch the motor off first: a submersible motor running without water can burn within minutes.
Can a submersible motor burn if it runs without water?
Yes. A submersible motor is cooled by the water flowing past it. With no water flowing, it overheats quickly and the winding can burn. A starter with dry run protection stops the motor before that happens.
How does a starter know the borewell is dry?
A BTCO starter watches the motor’s current. When the pump runs without water, the current drops below normal, so the starter shows Dry Run Trip and stops the motor. No sensor is needed in the borewell.
What is an air lock in a submersible pump?
Air trapped in the pump after it has run dry or been pulled out. The motor turns but the pump can’t push water. Switch off, let the water level settle for 15 to 30 minutes and start again. If it keeps happening, have the non-return valve checked.
Why does my pump give less water than before?
If the water reduces slowly over months, the pump impellers may be worn by sand, or the strainer may be choked. If it reduces during a run, the borewell water level is dropping. The current on the starter’s display helps tell them apart.
Will the starter restart the motor after a dry run trip?
Yes. A BTCO starter waits for the dry restart time you set, so the borewell can refill, and then starts the motor again by itself.
Get a starter that stops dry running
Call or WhatsApp us with your motor’s HP and your power supply. We’ll suggest the right BTCO starter, or send you to your nearest BTCO dealer. More answers in our motor starter FAQ.
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