Sound like the RFM69HW might get that range:http://lowpowerlab.com/forum/index.php?topic=114.0Buy it from ebay for about $4 each. You have to wire up your own antenna, so you can look into how to make the signal more directional. It communicates with Arduinos visa SPI.What are you using for the water level monitoring? An Arduino?
What is a "free slate" pressure sensor?I've been using Omega PX309 pressure sensors to monitor water tank levels for many years (we are on a rainwater system for home and garden) and although they are expensive, they are absolutely rock-solid. I can easily resolve a 1-gallon difference in a 3000 gallon tank over a long period of time, and detect the tiniest of leaks. The only difficulty I've ever had is with local air pressure differences. The 1500 gallon pressure tank for the house is located about 1000 feet away, 120 feet up on a hill and I monitor its level by measuring the pressure at the house. When the wind is blowing, local air pressure differences sometimes lead to false readings, but for the most part they can be ignored.
It exceeds the accuracy of the sensor and the arduino. Perhaps a 1 gal / time period measured over several time periods.
I've built a water tank monitoring system that logs water usage at a tank 1500' from our house in hilly terrain. The most direct path has lots of trees and is far from line-of-site.
QuoteIt exceeds the accuracy of the sensor and the arduino. Perhaps a 1 gal / time period measured over several time periods.l use the analog version of the PX309 (0-5V output) and an external, 12 bit ADC. I take 64 readings of the ADC and average them to produce a 13 bit result, resulting in readings in the range of 0-8191 for a 3000 gallon tank. After subtracting off the zero water level reading, the end result is still better than 1 part in 3000 accuracy, which I have verified by dumping a known quantity of water into the tank. The Omega gauges are high quality measuring instruments!
Can the sensor just be dropped into the tank or does it have to be mounted through the tank wall?