Topic: Waste tank gauges

pirate    -- Jun-29-2021 @ 10:35 AM
  What type of waste tank senders do people have?

There appears to be either probes of different lengths with a current passing between or floats up poles.

Can anyone give any experiences either way please these are for toilet tanks.


annville    -- Jun-29-2021 @ 10:43 AM
  Hi Andy electric tube type is best, float ones can get snagged and need a larger hole with multiple screws, while tube type just need a threaded socket molded in top for tube to screw into. John

ruby    -- Jun-29-2021 @ 11:07 AM
  Tube type, my problem was tank is incredibly shallow so getting an accurate measurement is nearly impossible.

Shows empty for ages and then goes almost immediately straight to full  


L'sBelles    -- Jun-29-2021 @ 12:08 PM
  I just look down the loo when flushing and I can see the level but I understand this technique only works if the toilet is directly over the tank.
I would avoid anything with floats whether on a tube or swing arm because they could easily get snagged by the contents of the tank so the conductivity probe type appears to be the best idea.
The tanks are generally quite shallow so do not expect good resolution from empty, quarter, half, three quarters etc. just ensure that it is set to be accurate at full with sufficient headroom in the tank for one or two more flushes prior to arranging a pump out.

This message was edited by L'sBelles on Jun-29-21 @ 1:11 PM

Luise    -- Jun-29-2021 @ 5:14 PM
  Is it a metal tank? Perhaps consider a contactless ultrasonic level sensor? Mine's a Vetus (the water tank sensor is from Gobius) but neither is really necessary for me, the tanks are plastic and I can see the level(s) from the outside...


pirate    -- Jun-29-2021 @ 7:27 PM
  The tanks are built in as had straight through toilets originally, Alpha craft

Your thoughts seem to agree with mine that anything that relies on floats are likely to get "clogged up"
Thanks for the feedback so far.


pirate    -- Sep-3-2021 @ 5:01 PM

I fitted one of the electronic units from Norfolk marine and fingers crossed it seems to be working ok.

If it continues I'll fit one to the rear toilet tank also.


Hylander    -- Sep-4-2021 @ 6:37 AM
  The only snag is one or two flushes isnt a lot of use when you are a long way from a pump out station ie down South.     You would think in the 21st century someone would come up with an answer.    As said one minute you have plenty of room and the next its 'panic stations'.

Women dont nag they just
things out...


annville    -- Sep-4-2021 @ 11:30 AM
  Hi Hylander It's called a bypass/diverter valve from LeeSan. John

This message was edited by annville on Sep-5-21 @ 12:14 PM

L'sBelles    -- Sep-4-2021 @ 4:38 PM
  Hylander wrote "You would think in the 21st century someone would come up with an answer. "

There are answers but not at a price your average boater would be prepared to pay.
A time of flight ultrasonic level gauge, for example, would resolve to better than 1mm liquid height or a radar unit might even be better than that. However, a simple single transducer and display transmitter would more likely be in the £1000+ bracket and not tens or hundreds of £'s.

The problem is waste tanks are generally large surface area but shallow. Therefore, a tiny increment in liquid height is a significant volume of liquid and to measure small level changes requires decent technology which costs money.
A diesel tank, conversely, is usually very deep in comparison to a small surface area and a simple float and potentiometer device can determine level changes of several cm with acceptable accuracy and also be produced economically.

This message was edited by L'sBelles on Sep-4-21 @ 11:03 PM

pirate    -- Sep-6-2021 @ 8:40 AM
The sender on this unit has a "full" probe about 2 inch long so on most tanks this gives some lee way. On our tank this was probably 15 to20 % volume so unless it was after a particularly good night on the ale not a great panic to empty.


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