How do I reduce interference/echo on HC-SR04

Hi all!

I've been working on a project where I need to measure the water level within a small underground compartment which measures 70x60x40cm (hxwxd).

I'm currently using a Hc-sr04, I'm getting good readings against a wall but when I put the device into the small compartment I get completely incorrect readings when at the top of the compartment. Instead of reading say 70cm it says 1cm. When I move the device down the height of the compartment to 30cm I start to get correct readings. I'm guessing I'm getting echo's due to the small area, is this correct and if so is there anything I can do to solve this? Appreciate your help.


That is they way such devices work. Not an appropriate sensor for such a project. Search the forum for some of the others that have had the same results and their potential solution.


Avoid using electronic circuitry in an enclosed, humid space. It be destroyed within weeks by condensation and current flow.

Floats with external sensors are one way to go.