How accurate are the holding tank gauges on your RV?


Are your RV’s holding tank gauges reliable? Do they accurately show the level of your  holding tanks — black, gray and fresh water — and LP gas?

Or are they never or seldom correct? Curious minds would very much like to know.

It may take a moment for the survey to load, so please stand by.

Join the Discussion

30 Comment threads
13 Thread replies
Most reacted comment
Hottest comment thread

This site uses Akismet to reduce spam. Learn how your comment data is processed.

newest oldest most voted
Notify of
Stephen Willey

I checked “very accurate” because I replaced the stock gauge with an electronic tank monitor that uses foil tape on outside of the tanks to sense levels. Bit of work, because the new system needed one more wire from each tank than the original. But it works great. HEY! this hgas been an issue for decades. Why don’t manufacturers update and quit using those cheaper pin through the tank gauges that always foul up?

Colin Grant

My black tank gauge is useless. I`m lucky though if I shine a flashlight down the toilet with the slide open the tank is directly visible below. My grey tank is reasonably accurate but if you fill to the max it will come out on the shower floor which isn`t a problem. Fresh and propane are good. This is on a Pleasure Way Sprinter class B, an older model.


They worked fine for three seasons and that was it. Even had the tanks power-washed and replaced the sensors. Tried almost every tip I read here on RVTravel. Bought cleaners from Amazon with no success. So I just dump them every few days.

Bluebird Bob

We have had a MicroPulse indicator with probes. Have had it now for over 10 years and VERY accurate. Love it!


Ours have not worked from day 1. When we did our inspection I noticed gray tank #1 was reading 3/4 full, gray tank #2 was 1/2 full and the black tank full. The dealer knew they did not work and stated there was nothing they could do about it. According to them that was worked into the price of our brand new 5th wheel. That took them 3 months to get. I never tried getting Grand Designs to warranty it, because I don’t want the dealer to take a few months trying to fix something that they know doesn’t work… Read more »


I think one of the choices should have been accurate enough. Usually if it reads 1/2 a tank it gets emptied.

Lynn Benzel

I think the gauges suck. Never tried to correct. Why put out the money. Factory should make it right.


My gauges work fine. I do flush and empty tanks frequently and never but toilet paper in black tank. The outside propane tank gauge is accurate but the gauge inside RV is not accurate. This Class C is my 4 th RV been RVing about 6 months a year for last ten years and RV ing since 1995. I’m 71.

Jim Thompson

So how do you wipe???


For anyone who is interested, here is the link.


My readings on my tanks are accurate because I installed SeeLevel tank sensors. About $100. Worth the price.

Vanessa Simmons

Being solo I empty the black tank every other week and usually the bathroom gray tank at the same time to rinse out the hose. The gauges haven’t been accurate since I bought it two years ago. The kitchen gray tank I empty as needed…sometimes when the water backs up in the sink! 😉

Carl M

My Tech Edge sensors are working well after six months. Install involves a lot of crawling around under the trailer to install foil tape on each tank and run a 3-conductor cable to each tank. The system needs to be properly calibrated after install. My tanks are shallow, so being out of level gives an incorrect reading.

Daniel Pankiewicz

No matter how I empty, the chemical used, multiple clean water flushes, gauges still read full . Thus useless in my opinion.

robert garder

The Seelevel system is available from I have had mine installed for 4 years and am very satisfied with the system. Installation is easy as you can utilize the existing wires. The hardest part is gaining access to the tanks to attach the sensing strips.
I would buy this system again.


Mine are “somewhat accurate AND generally reliable.” Probably the case for many, but can’t choose it the way the choices are written.

Rocky J

I read a comment several years ago that one person recommended putting Calgon in black water ….this will prevent any materials sticking to the sensors.
Note..we still use soap and water to clean out the tanks!!

Gene Bjerke

Our monitor levels (lights) are reasonably accurate for everything but the black tank, which is useless. On longer trips, I have begun to use a system based on the fact that the total capacity of my sewage tanks is pretty much equal to the capacity of my fresh water tank. This is done to keep the rig balanced as the water is transferred from the fresh tank to the waste tanks (some of it via the humans aboard). Thus when the fresh tank is getting low, it is time to dump the holding tanks. I dump and reload at about… Read more »

Karen K Willis



I have the old fashioned electrical contacts drilled through the tank walls but the installer did not place them accurately. So, starting with an empty tank add water by the bucketful (most buckets are calibrated) until the gauge flicks over to 1/3 full and note the number of gallons added. Continue until you get to 2/3 full, then again till it reads Full. Post a little chart by the gauge and never again be concerned with a reading that’s much higher than you expected.


I checked very accurate, however they are not properly placed, so the level indicators very accurately shows when the level is at the sensors, but the sensor is nowhere near where it is labeled, so on the fresh water tank, for example, the full sensor is placed at about halfway up the side of the tank. I can very accurately determine when the tank is full when water starts coming out the overflow. The grey water tank is pretty close to full when indicated, and we have never gotten the black water tank full (except when I forgot to disconnect… Read more »


For the record, most of the standard gauges that screw up, is primarily caused by not keeping the tanks free of stuff sticking to the sides of the tank. This can easily be corrected by flushing out the tanks with soap and water when you drive from one place to another. No need for any chemicals or odor cover ups. My biggest gripe with these gauges is that when it reads 1/3 full….it can actually be almost 2/3rds full, or 1/2 full, or 3/8 full and 1/3 full. There is just too large of a difference between 1/3 and 2/3.… Read more »

Fred P Burns

My Tech edge tank sensors (outside on the tank walls) are inaccurate & very hard to read. The fresh tank is fairly accurate because it sets level, but the grey & black tanks are tilted at an angle to facilitate better draining, which causes the drain end of the 6 ft long rectangular tanks, where the sensing tapes are applied, to fill up faster than the raised end, thus giving a reading of being much fuller than they actually are. The digital display also flickers a lot & rarely shows a solid, readable number, so the readout could be anywhere… Read more »

Thomas Becher

Bought and installed sea level and they where very good but also very inaccurate. My tanks( 4 of them) were very shallow, about 6 inches high. The sensors had to be placed almost together. Any little movement threw the reading off. I had them previously on a motor home with higher tanks,(3) and worked great. That’s why I bought them for my fifth wheel. Before buying them I’d check the height of the tanks if possible.If diy, you need to run new wires to the sensors so you need to access the tanks and new readout. It is not an… Read more »


Had my 2018 in for Warranty service and had a rep from KIB recalibrate the gauges twice in the 5 days we were there. NONE of them work properly the day after we left. Save yourself some grief, don’t buy K I B


Yep, sorta. The KIB (and any other “resistor-ladder” based) display relies on small changes measured through a single wire, and even modest “sludging” bumps one threshold into the next. Being a nerd, I invented my own self-calibrating replacement display that is 100% accurate to the same 33% precision. Not difficult to make for under $10 if readers know arduinos…

Tommy Molnar

Wolfe, I looked up “Arduino” and found that it’s waaaay over my paygrade. We just learned to ‘guesstimate’ how full our tanks are – and we do quite well. . .

Gordon Herrmann

The Seelevel system is available from I installed them a few years ago and the work perfectly. Gives you a percentage rather that just 1/3, 2/3 etc. They mount on the outside of the tank and are very accurate if you calibrate them properly.


Just to be correct… 1/3 and 2/3 are percentages as any 5th grader can tell you that they are 33% and 66%.


Sorry, 1/3 and 2/3 are fractions.


My tank level monitoring system is very adequate but the display was inside the coach above the co-pilots seat. I wanted a display in my service bay that I could read outside. So I purchased a SeeLevel Tank Monitoring System and installed it with the display in my service bay. I now have two systems and like them both. The sensors are NOT inside the tank where they can get crapped up but rather attached to the outside of the tanks.

Keith Miller

I have brand new 2019 fifth wheel. Black water tanks show 1/2 to 2/3 full when tanks are emptied and rinsed thoroughly.

Tommy Molnar

So Keith, your stuff is normal eh?


The gauges in our 5th wheel aren’t worth a crap. After I have emptied all 3, they will most all ways show 1/3-2/3 full. I empty the black tank first, flushing all-the-while when it is being emptied, closing the valve letting it fill a bit, opening again then repeating several times. After the black tank has finished it’s dumping the first time I will open one of the two grey tanks then the other and leave them open until there is no more water flow, (empty?) I would guess, but the the gauges tell the story, well maybe not the… Read more »

Captn John

Have not looked at those in many years on many units.


My gauges are Horrible, especially the Black Tank. The Grey Tanks seem to work OK. So, since it is only 2 of us using the RV, we usually can safely go for 4 days before needing to dump the Black Tank. Of course the Greys get dumped as needed. I have flushed and Rinsed the Black Tank Numerous times from the Top down and with the Built in Tank Flush system. Sometimes the gauge will show 1/3 but most of the time is shows 2/3rds or even Full, when I know I just emptied it completely! So it goes, just… Read more »

Ed Kilburn

Sea level works great, always know my tank level.


I too installed the “see level system and it accurately shows full, empty, and 4% steps between the two. The sensors mount on the outside of the tank so they don’t get contaminated with “stiff”.
Factory sensors, not so good.

Brian Tillotson

They were horrible until I installed a seelevel system now the levels are extremely accurate

Dave Telenko

Not heard of a “seelevel system”. I bet there’s a group of RV’s that would like to know what they are & where to get them!


Google Seelevel Tank Monitoring System and you will have plenty of choices as to where to purchase the model of your choosing. I purchased mine from but they are also available from Amazon and other places on the Internet.


Canadian outfit that makes the SeeLevel guages for fresh and holding tanks. Very good system, and uses the typical wiring already in the RV for OEM guages.

Brian Tillotson

Thank you Lance. I forgot to include the link in my post