afremont:
For what it's worth, I think Lefty's idea of the spool letting down a weighted float on the self weighing platform is the best solution in many ways, including reliability.I suppose you could drop a glass marble into the well and time how long it takes to get the splash back.
Did you saw Plan A? I vote it as Plan A.
terryking228:
hi, a 420 ft deep well must be feeding from an aquifier far below.What is the distance down to top of water in the usual situation?? If it's 300 feet down and you want to use ultrasonic, you might make a platform you can lower on a long cable, and get the ultrasonic down lower.
However in your environment you may not need ultrasonic. A short audible beep of maybe 400Hz should give an obvious echo. Try it. Or maybe 3000Hz from a small "tweeter".. A sound sensor like one of these might be enough to receive the echo: http://yourduino.com/sunshop2/index.php?l=product_detail&p=304
Google this more; it must have been done....
DISCLAIMER: Mentioned stuff from my own shop...
Audioable sensor, first I saw this, two things against this idea;-
However count OP's environment. This could be perfect idea.
Here we go, Plan G.
Ok, look like I am now more interesting measuring water level in a borewell than OP!
Here is the last Plan I post;-
Plan H: laser-based water level sensor.
The pressure sensor will probably be much cheaper than the waterproof cabling down to it. Just try to keep water out of something submerged in a couple hundred feet of water.
When you order the sensor you also get a waterproof cable already "installed". I don't think that you can extend the cable by yourself because one part of the cable is a "air tube" used for barometric pressure compensation.
But soon I will know because I am waiting for a sensor to arrive.
I will measure the water level in a large dam. Because we have alot of ice in the winter I have not found any other alternative than a pressure sensor.
I think I heard of the following idea in the context of measuring the depth of "water" in black water tanks.
A pipe with an open bottom end and sealed top end reaches from near the bottom of the liquid - to the top of the well. Use the air pressure in the tube as a proxy for depth. That way nothing sensitive needs to get wet, be subject to high pressures or be inaccessible. You would need some way to calibrate the device initially. However I have no idea whether the pressure differences for the range of depth variation in your well would be sufficient to be detectable.
How do you get water out of the well? is there scope for using part of that process to estimate the depth in the well?
...R
There are probably sound frequencies that would echo better depending on the distance to water being half wave or full wave rather than some fraction. Maybe the whole length can be turned half-test/half-musical instrument getting the strongest return.
Advantage: equipment stays at the top with no permanent installation necessary.
zoomkat:
Curious, have any of you ever worked with wells, or have wells and are familiar with how your wells work?
You mean I never arise cow, eat steak is prohibited? just kidding.
straight answer is no, not until today. That is why cat dish sensor come out 
olof_n:
The pressure sensor will probably be much cheaper than the waterproof cabling down to it. Just try to keep water out of something submerged in a couple hundred feet of water.
I will measure the water level in a large dam. Because we have alot of ice in the winter I have not found any other alternative than a pressure sensor.
I am interesting to learn;- how did you compensate ice with water in the winter? did you measure ice depth as well? where is the dam? Is mix fresh water and salt water is going to be problem?
Robin2:
I think I heard of the following idea in the context of measuring the depth of "water" in black water tanks.A pipe with an open bottom end and sealed top end reaches from near the bottom of the liquid - to the top of the well. Use the air pressure in the tube as a proxy for depth. That way nothing sensitive needs to get wet, be subject to high pressures or be inaccessible. You would need some way to calibrate the device initially. However I have no idea whether the pressure differences for the range of depth variation in your well would be sufficient to be detectable.
How do you get water out of the well? is there scope for using part of that process to estimate the depth in the well?
...R
I know what you are talking about, I guess it should be perfect fit for water tower, but here we are talking about borewell.
GoForSmoke:
There are probably sound frequencies that would echo better depending on the distance to water being half wave or full wave rather than some fraction. Maybe the whole length can be turned half-test/half-musical instrument getting the strongest return.Advantage: equipment stays at the top with no permanent installation necessary.
Hey, Terry got second supporter. if OP go this route, please do not forget hangup sign "Speaking is Strictly Prohibited around Sensor".
sonnyyu:
GoForSmoke:
There are probably sound frequencies that would echo better depending on the distance to water being half wave or full wave rather than some fraction. Maybe the whole length can be turned half-test/half-musical instrument getting the strongest return.Advantage: equipment stays at the top with no permanent installation necessary.
Hey, Terry got second supporter. if OP go this route, please do not forget hangup sign "Speaking is Strictly Prohibited around Sensor".
You might check the thread to see the first person to mention echo measure besides short range ultrasonic units.
But making a standing wave in the borehole might only help with fine-tuning measurements gotten from echoes. It doesn't tell how many wavelengths or half-waves. It only tells you when they fit, what frequencies fit, etc.
I would use a clicker to make the sound for echo.
PS don't forget that the speed of sound varies with air temperature and to a much lesser extent, humidity.
GoForSmoke:
You might check the thread to see the first person to mention echo measure besides short range ultrasonic units.
I am sorry. I think correct order is you, terry, then myself. I am your second supporter !
I don't understand why you think there is a difference.
...R
sonnyyu:
I know what you are talking about, I guess it should be perfect fit for water tower, but here we are talking about borewell.
Robin2:
I don't understand why you think there is a difference....R
sonnyyu:
I know what you are talking about, I guess it should be perfect fit for water tower, but here we are talking about borewell.
I guess is location of sensor.
The hole is going to be 420 feet deep, but how much of that will be water? Could you hang an arduino with a ultrasonic sensor on 400 feet of cable, so it can measure a 20' (or something) variation at the bottom?
I like the float on a string method. Keeps all the expensive stuff above ground, and gives you a large range of measurement. If you don't pull the float to the surface for every test, you might want to use a pre-marked rope so you can tell if it has slipped.
Hi,
harivemula:
I am looking for ideas on how to measure water level in a bore well using arduino boards, and which boards and sensors I need to use.
Are you trying to make a pump-off controller?
sonnyyu:
zoomkat:
Curious, have any of you ever worked with wells, or have wells and are familiar with how your wells work?You mean I never arise cow, eat steak is prohibited? just kidding.
straight answer is no, not until today. That is why cat dish sensor come out
If the well is an actual working water well, then the well bore will most likely be almost totally filled with the pump discharge piping, power cabling, pomp retrieval cabling, and such. Anything else going down the well bore is probably a remote possibility. The OP might try monitoring the pump discharge pressure at the well head as a function of the well water level.
I am interesting to learn;- how did you compensate ice with water in the winter? did you measure ice depth as well? where is the dam? Is mix fresh water and salt water is going to be problem?
I am not finished with my project yet. Still waiting for my sensor to arrive.
This weekend I tested out a GSM-module that will send SMS if the water level get to high/low (will also recive SMS and send an answer with the current waterlevel).
I looked at a professional solution that costed 4000$ and it used the same kind of sensor that I ordered.
The problem with ice (fresh water) I think is that you can get air between the ice and water (because the water level change a lot).
The sensor has to be placed below the ice.
I don't think it is a problem if the ice rise above the water in the winter, also 1m of snow above the ice is not uncommon 
In my concept (and it's no more than that) the sensor would be at the top of the well and therefore would be readily accessible.
I'm not saying my idea would work, but I wouldn't like to see it discarded due to a misunderstanding. Something like this where "s" is the sensor and "w" is water. (and the pipe doesn't have perforations down the side )
| s |
| |_______
| | ground
| |
| |
| w |
| w |
w
...R
sonnyyu:
I guess is location of sensor.
olof_n:
I looked at a professional solution that costed 4000$ and it used the same kind of sensor that I ordered.
The problem with ice (fresh water) I think is that you can get air between the ice and water (because the water level change a lot).
The sensor has to be placed below the ice.
I don't think it is a problem if the ice rise above the water in the winter, also 1m of snow above the ice is not uncommon
Thank you for share the detail with us. I have last question;- "air tube" for winter, Is it stay between the ice and water? How to make sure it remain that way?