All around the water tank, waiting for the rain...

Having the luxury of mains water means that I don't really care in fanatical detail about the state of the dam water levels for Perth (except that "it's lower than it should really be"). However with our new place being entirely dependant on rainwater collection off the roof into storage tanks, I'd like to know the levels of the various tanks (and therefore the volume remaining).

So, what's available - simplest is knocking on the side of the tank and guessing from the sound how full. Not terribly reliable or hi-tech, but is cheap. Dipstick also cheap, but requires removing filter cover. Next up are external gauges - Our tank supplier stocks the Yaktek Levetator, but that's not really any good when I'm not on site. Hence, it's time to investigate the electronic options:

This thread on whirlpool mentions the Electrosense Aquagauge, but at $265 each plus telemetry thats not cheap. The Jaycar ultrasonic one may be OK, but as it doesn't have a serial / usb  output from the display, I'd need to hack up something to parse the RF (as others have done). So datasheet hunting time:

The MaxBotix series looks like it's pretty much ideal - 1mm resolution, 5m max range, weather resistant. Annoyingly I can't see it cheaper than the ~100 USD on the manufacturer site (sparkfun et al. only have the MB7360 not the MB7369), but at least there's a local supplier.  A slightly different model (MB7060) is being used by the flood network.

Next up is trying to work out how to connect them - My options are:

• Wired - Etherten or possibly something as simple as serial-ethernet adaptor
• Wireless - wemos / ESP8266 for wifi (power hungry?)
• Wireless - rfm type TX/RX setup to basestation
• lora - nice but possibly expensive as I'd need a gateway.

I suspect this particular blog entry will get updated as things progress..