RV Holding Tank Monitors

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May 24, 2009

Sometimes the smallest of things can be the most frustrating. Take for example, RV holding tank monitors. You push a button and the monitor display is supposed to tell you the levels of fluid in your holding tanks using a few simple indicator lights. One light means empty, two lights means 1/3 full, three lights means 2/3 full, and four lights means full. The problem is that these simple indicator lights are notoriously inaccurate and very misleading.

Take for example the case where the monitor is showing two lights for your fresh water tank level, meaning you have 1/3 remaining. As soon as you use a small bit of water, the level drops below the 1/3 level and now the indicator lights show you are empty. This is true no matter the size of your holding tanks. The standard sensor arrangement is such that it cannot measure levels any more accurately. How can you get more accurate readings for any and all of your holding tanks? Modify your RV with a See-Level Tank Monitor System.

The See-Level Tank Monitor System lets you know your holding tank levels by percentage rather than by the so called “idiot lights”. It does this by using a different type of sensor that is not subject to fouling by debris inside the tank, which can also contribute to inaccurate readings. The standard type of sensor goes through the wall of the tank whereas the See-Level sensor is attached to the outside of the tank and reads the tank level electronically. This way provides a much more accurate reading and expressed as a percentage, is easy to know where your tank levels are quickly.

Modifying your RV with one of these systems is fairly straightforward. But you need to have access to your holding tanks. For some RVs with enclosed underbellies, this can be a challenge. You will have to remove the underbelly cover to get to your tanks. Once you have access, this mod can done in a matter of a few short hours.

The See-Level kit allows you to reuse your RV’s current tank monitor wiring, which shortens installation time substantially. The new sensors are actually a circuit board with adhesive backing that sticks to the side of your holding tanks. They can be cut to length to fit almost any height tank. And in the event that your tank is taller than the sensor, two sensor strips can be used together. Just peel, stick, and connect the wiring from the old sensors to the new sensors, using the provided connectors.

Fitting the display panel is equally straightforward. Simply remove the old “idiot light” display, remove the wiring from the old display, and then attach the wiring to the new digital display using the connectors provided. Wiring instructions for both the display and sensors are included with the kit and should work for most standard RV wiring.

By doing this mod, there will be no more guessing as to how much fresh water is left or how full the waste tanks actually are. And after a few times going through filling and emptying your tanks, you’ll get a good feel for what your water usage is and how you can better manage your holding tanks.

Have you done this mod? Please share your experience by commenting below. Happy modding!

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  1. Richard

    The monitors sound great but what do you do when the light panel includes a battery monitor?

  2. Bill Mann

    I just installed the SeeLevel on my Allegro Bus. I ordered the 6 in. high sensors that closely match my tank heights and require no cutting; they also have more measuring “points” along the full height than the regular ones, but cannot be stacked for taller tanks. I ran new cables for my install so that I could keep the OEM system as a backup. Finding locations to install the sensors proved somewhat difficult. On the Tiffens, there are lots of steel supports to retain the tanks and you must have the sensors at least 1 in. from any metal. I had to install the sensors for the fresh water and black tank on the passenger side of the tanks, and the sender for grey tank on the driver side. No big deal since I was running new power cable and ground from passenger side anyway over to the driver side and the wet bay. I added a second display in the wet bay so that I can monitor the tank levels as I drain the tanks.

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  5. Bluebird Bob

    Try MicroPulse. Easy to install and a 5 year warrenty.
    Had mine 3 years now and not possible for stuff to hang up on.

  6. I have just picked up a new born free coach at the factory in Humboldt Iowa. I asked the R+ D people there to remove the standard sensors that everyone complains about and install the new Horst Miracle probes in the black and grey tanks. This was done before I picked up the coach, along with the new Solar system we set up with AM Solar, I now have a Class C where I can dry camp and use the microwave and coach 120 outlets without the genny

  7. pkunk

    I did do this on my old Allegro and loved the increased knowledge that it gave me on my usage in addition to the reliability factor. I plan on an upgrade to my present MH in the near future.