Need help with water pump control

Thread Starter

mohsen 2012

Joined May 15, 2014
31
Hi guys
I have 1000L water tank and i want to build a circuit to automatically power on the water pump to fill the tank.
The water company in my country dont supply water all day long and she has no fixed time to redistribute !!!
I think that this simple circuit will be good :

https://www.circuits-diy.com/wp-con...l-Sensor-Or-Liquid-Level-Detector-768x432.jpg

I will use a 5v to power it and a 5v relay instead of led , for the probes i drill the plastic source tube and use L screw like this :

20221105_223619.jpg
20221105_223904.jpg
And i use a 15 meter cable from the probes to the circuit at my home because i live on the third floor , and the water pump and the source tube is in the cave .

But the problem how can i turn it off when
the tank is full ?
I wait your thoughts and advice friends.
Thanks
 

dendad

Joined Feb 20, 2016
4,496
1667686219218.png
There are float switched like this that can directly control a pump.
Make sure you wire so it turns off when floating upright so the pump stops when the tank is full.
1667687126162.png
I also found a photo of what is inside the switch.
1667687368980.png
 
Last edited:

dendad

Joined Feb 20, 2016
4,496
That simple level sensor is a bit of a toy and will not be reliable over time. You do not want DC on the probes as that will cause them to corrode.
One water detector I made for irrigation control had an Arduino that periodically generated a 50% PWM signal that was couple via a capacitor to one probe, and then the other probe was couple via a capacitor to a diode rectifier and than fed to the Arduino analog input. The Arduino would wake up, read the analog input with no PWM running to set a base level reading, then the PWM was started and the analog reading was repeated. If the reading increased significantly, there was water.
IrrigationMonitor.jpg
Use stainless steel bolts for your probes.
Prpbes.jpg
 
Last edited:

Reloadron

Joined Jan 15, 2015
7,546
I would also suggest using a float switch. Problem with probes is they develop corrosion pretty quick depending on water quality. I spent time in the Philippines where when water was available it was pumped to a roof top tank and float switches were the best solution.

Ron
 

Jerry-Hat-Trick

Joined Aug 31, 2022
583
I’m assuming that the water supply doesn’t have sufficient pressure, i.e. head of water to get up to the top floor.
In your 1000 liter tank you could use a float switch as suggested by Reloadron but have you considered that the pump should not be switched on when there is no water being supplied? You might need a water pressure sensor switch in series with the float level sensor?
Years ago in Nigeria I used a small ground level tank, actually a lavatory cistern with ballcock to shut off supply when it was full, with mercury tilt switches in this and the tank in the loft to control the pump. Whatever you choose for a solution I’d recommend overflow pipes to the outside just in case of system failure!
 

Reloadron

Joined Jan 15, 2015
7,546
I’m assuming that the water supply doesn’t have sufficient pressure, i.e. head of water to get up to the top floor.
In your 1000 liter tank you could use a float switch as suggested by Reloadron but have you considered that the pump should not be switched on when there is no water being supplied? You might need a water pressure sensor switch in series with the float level sensor?
Years ago in Nigeria I used a small ground level tank, actually a lavatory cistern with ballcock to shut off supply when it was full, with mercury tilt switches in this and the tank in the loft to control the pump. Whatever you choose for a solution I’d recommend overflow pipes to the outside just in case of system failure!
Oh yes, good point. We have played this game before. You need to make sure your pump has supply to draw from.

Ron
 

MisterBill2

Joined Jan 23, 2018
19,033
Pressure switches are the way to go. One switch to verify that there is a supply to the pump inlet side, and another switch at the tank to sense that the pressure of the full depth of water. These can be the low pressure type switches like are used to sense the water level in wash machines that have automatic fill. Usually those are available on discarded wash machines because nobody can discover a use for them. You will still need a relay to control the motor, and it will need a second contact, probably, to keep the circuit latched on until the tank is full.
The pump supply sensing switch will start the pump whenever the supply pressure arrives, and so that will deal with the random times of supply availability.
 
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