# 2 mm accuracy in an affordable water level sensor (pressure transducer) - Does one exist? [closed]

I'm looking to conduct water level monitoring in streams and rivers for water resource engineering purposes. My plan is to use Arduinos and Raspberry Pis in conjunction with a pressure transducer, as Pis and Arduinos work with the telemetry system and water quality sensors that I have chosen for the project.

However, the standards in British Columbia, Canada (where I work) require that the sensor must have a 2 mm accuracy to collect "Grade A" data. Grade B data requires 5 mm accuracy, and as it turns out a pressure transducer with these accuracies are hard to find unless you spend >$500 per pressure transducer. Does anyone know if a low cost ($300 max, but preferably $50 to$150) pressure transducer designed for measuring water with 2 mm or 5 mm accuracy exist? I'm also open to other technologies as well.

Thanks!

Page 4 in the attached in BC's standards doccument is attached if anyone is interested in checking it out.

• Welcome to Engineering! This looks like a resource-hunting question. Such questions are prone to becoming out-dated, and are therefore considered off-topic for this site. – Wasabi Jul 19 '18 at 22:15
• Does it have to be a pressure transducer, or would some other mechanism be OK? – Jonathan R Swift Jul 19 '18 at 22:28
• I've been looking at other instruments such as ultrasonics. We actually purchased a MB7369 HRXL-MaxSonar-WRM (link below), but ultrasonics come with some qualities that make them less desirable than pressure transducers when measuring a fluctuating water level such as the case with fast flowing streams. – Rory G Jul 19 '18 at 23:24
• maxbotix.com/Ultrasonic_Sensors/MB7369.htm – Rory G Jul 19 '18 at 23:24
• I would vote to reopen this if it were rephrased as "what is a cost effective type of instrument for measuring water levels to 2 or 5mm accuracy?", although I admit I recognize I'm not in majority on my opinion about the on-topic-ness of these questions. I'm curious though, what does it even mean to measure a river height to 2mm? The water level certainly varies more than that across its profile! – ericksonla Jul 21 '18 at 20:50