Not if you have a leak in your tank, or anywhere before the sender.
Good point. In my case I left the old, semi-accurate on-tank gauge on. I also took good care of my plumbing and inspected my boat on a regular basis and maintain it to a high standard. Another thing is, if I were to run out of water unexpectedly, before the Watercounter indicated I should, I would
know there was a leak, rather than guessing.
The biggest nicety, IMO, about the WaterCounter is its measurement of usage; thus we learned how much various lengths of shower took, or different cycles on the laundry and dishwasher, even toilet flushes after conducting a test (since one flush is not enough to trigger the pressure switch). Like having FloScans for your water. Since we lived full time on moorings for several months a year, and prefer to anchor out when cruising, it became a very valuable tool. For weekend warriors or dock-to-dock cruisers, probably less of a tool and more of a "nice to have".
The boat has a "tank tender" up near the helm where you can switch between the two fuel tanks and water. Water had obviously not been calibrated or set up right, fuel read a little lower than actual, which was ok with me (on-tank gauges were very accurate). A multi purpose tank tender in one location is convenient, but without easy to access on-tank gauges becomes a single point of failure. And obviously, with irregular shaped tanks needs a whole calibration and cross reference process.
