Entry 001: An Intricate System of Pipes

As mentioned earlier, we get raw water from a local reservoir at a slow rate. For water storage we have a cistern that holds approximately 12000 imperial gallons. From there the water is pumped into an intricate system of pipes running all over the place. I am sure you don't want to listen to me rant about our complex water system. I think my father is the only person who really understands what every valve does. Anyway, we needed a way to tell how much water was in the cistern and just like that this here project was born.

I thought a lot on how I would go about making a water level meter for a storage tank. There are several commercial products on the market that serve this exact purpose. I am cheap and I didn't want to buy one of their fancy systems that is probably going to give me trouble later on. It appears that most of the commercial units use sonar or infrared ranging sensors to tell the height of the water. They must have some way to calibrate the gauge since every user will have a different tank size. I ended up deciding to build my own water level meter for my cistern. I wanted something simple and maintenance free. I needed something that was reliable so I wouldn't have to listen to my mother yell at me because the pump shut down (due to a lack of water in the cistern) when she was doing a load of laundry.

In my travels on Google, I came across this website. I doubt the owner of that site is the original designer of the circuit, since it can be found on many different sites around the internet. If somebody knows who the original designer is, I would be happy to give them the credit they deserve. I will include the design below just in case that website evaporates in the future.

Water Level Indicator with alarm

 

This circuit not only indicates the amount of water present in the overhead tank but also gives an alarm when the tank is full. The circuit uses the widely available CD4066, bilateral switch CMOS IC to indicate the water level through LEDs. When the water is empty the wires in the tank are open circuited and the 180K resistors pulls the switch low hence opening the switch and LEDs are OFF. As the water starts filling up, first the wire in the tank connected to S1 and the + supply are shorted by water. This closes the switch S1 and turns the LED1 ON. As the water continues to fill the tank, the LEDs 2, 3 and 4 light up gradually. The no. of levels of indication can be increased to 8 if 2 CD4066 ICs are used in a similar fashion. When the water is full, the base of the transistor BC148 is pulled high by the water and this saturates the transistor, turning the buzzer ON. The SPST switch has to be opened to turn the buzzer OFF. Remember to turn the switch ON while pumping water otherwise the buzzer will not sound!

When I saw this, I wondered why I didn't think of this design sooner. It is dead simple and a similar circuit could be designed with transistors. I decided to build an exact copy of this circuit to keep my design work at a minimum (I am lazy). Anyway, I don't need the buzzer to warn if the cistern is going to overfill (there are already systems in place for that). I also plan on having more resolution on the gauge, so if I build two of these circuits, I can double the number of LEDs to eight. That should do nicely. I figured this was the ticket so I went about gathering the necessary parts.