My black tank level is incorrect . It always shows 3/4 full . I do not plan to fix it as I know it is a common problem. I just wanted to ask the experts here . How to you know (or guess) when it is time to dump the tank without looking at the level indicator ?thanks

If you use your rig a lot you will pretty much just know when it is getting full. But if nothing else when it gets full you will know when you flush. It is a pretty simple system. It may burp a little when you flush when it is real full. Eventually you will actually see the contents coming up the 3 inch line, hard to miss. Of course you want it to be at least 2/3 full when you dump so there is enough liquid to get rid of all the solids. Keep in mind the worst than can happen is you could end up with a little in the bowl. Not a crisis.

There is probably not a rig over 6 months old that does not show 3/4 full. Don't worry about it, the grey tank will fill a long time before the black tank.

What type of RV do you have?The reason for asking is, in many trailers and motorhomes, you can look down the toilet and see the liquid level. that makes it easy to check the level.In some, that cannot be done due to the height of the toilet above the tank, and sometimes there is even bends in the pipe. In most of those, the toilet will "burp" when flushed, showing the tank is full.With experience, you will know how long you and your family can go before dumping the tank is needed. For instance, when we were full-timing, I knew that in about a week or 10 days, the tank would be full enough to be dumped. I wanted it to be more than 1/2 full, but not completely full, then I would dump a bucket or two of water down the toilet with the valve open to rinse it. I never checked the gauges, I knew they would lie to me.

mowermech , We have a Winnebago 24F C . thanks

dave17352 wrote:If you use your rig a lot you will pretty much just know when it is getting full. But if nothing else when it gets full you will know when you flush. It is a pretty simple system. It may burp a little when you flush when it is real full. Eventually you will actually see the contents coming up the 3 inch line, hard to miss. Of course you want it to be at least 2/3 full when you dump so there is enough liquid to get rid of all the solids. Keep in mind the worst than can happen is you could end up with a little in the bowl. Not a crisis.You must not have a flush kit installed.We hook up the drain hose to the dump station, pull the slide valve for the black tank, allow to empty, then close the slide valve. Then pull the slide valve for the grey tank, allow that water to chase out the black waste in the hose. then close the grey tank valve. to flush the black tank, we simply hook up a water hose to the flushing fitting and partially fill the black tank then empty again. repeat as required to insure the tanks flushed out.

Pls help - My black tank level is incorrect | Good Sam Community

19 Replies

RCMAN46
Explorer
May 27, 2014
Harvey51 wrote:
The level of the freshwater tank is a good indication of how much has gone into the waste tanks, unless you are bringing large quantities of liquid refreshments aboard.

My black tank level indicator has never worked.

I have never worried as my fresh water is less than my black and gray tanks. When I run out of fresh water I go to a dump and dump the tanks and refill the fresh water.

If at a campground using their water I go two days then add about three full toilets bowls in the black tank and dump. I have found the wife and I can go 4 plus days on the black tank.
pennysmom09
Explorer
May 27, 2014
We have had our fiver just one year. The sensors have never been accurate so we don't even use them. Experience has taught us when to empty....water in the shower, and looking into the toilet. Who needs sensors! :)
dave17352
Explorer II
May 27, 2014
sharker6 wrote:
Who needs a sensor? When your tank is full your feet get wet. Same with the grey tank and the shower.
Well you would really have to have a big bladder to get your feet wet using the stool. You should be able to notice when the slider is submerged!:W
sharker6
Explorer
May 27, 2014
Who needs a sensor? When your tank is full your feet get wet. Same with the grey tank and the shower.
bob_b1
Explorer
May 27, 2014
I'd just ignore it. I've never filled the black tank in the last 11 years of ownership.
You'll need to dump that gray tank more than Twice before the black tank needs dumped.
If you still are still convinced that you need to fix the sensor, do a search on the GEO Method. There is a lot of good information on tank cleaning in his post.
mgirardo
Explorer
May 27, 2014
Apparently I am one of the lucky 10% that doesn't have this problem, at least on a long term basis. Every once in a while when we are camping, if I don't rinse out the tank after dumping, the reading may not be correct. Probably some TP stuck on the sensor.

Fortunately our MH has a built in tank rinser which definitely works well. After 5 years, our currently empty black tank reads Empty on the sensor. I've never used anything to clean out the tank other than rinsing it with water.

-Michael
wa8yxm
Explorer III
May 27, 2014
I would say 90% of all RVers have your problem.. I just ignore the beast.. My tanks have other ways of saying "DUMP, SOON".

There are 3 or 4 different sensor sets.

Standard is a row of nails, or equivlant of nails, these penetrat the tank wall, Just a metal rod inside the tank, if the rod is WET, then clearly the level is at least that high. The "Gauge" senses which rods are wet and shows the level.. The problem is that slime on the walls keeps them wet all the time.

HORST miricle probes are "1b" for this discussion, Same type of sensor but they have done a few things to make them less suspectable to slime.. Supposed to be good, I hope to install later this year.

There are Pneumatic sensors.. These measure pressure at the sensor point, if the pressure on both sides of the sensor is the same, It's not that full, If the pressure is higher INSIDE the tank, it is that full... I have only seen these in the instruction manual for my macerator toilet. alas the sensors were NOT installed.

In theory you could weigh the tank. Several companies make load cells that could do this.

SEE LEVEL sensors use some sort of electrical sensing to measure the level inside the tank.. People who have this type of sensor.. Say it works well.. The only problem is if the sensor falls off the tank These are the Cadillacs of the sensors.
wbwood
Explorer
May 27, 2014
As others said, after using it a few times, you will know. Also, as I heard someone mentioned on here, when it burps. Yes, it will burp when you flush it and it's full.
cochise49
Explorer
May 27, 2014
Have had four RVs that had internal tank sensors. None were still working after the first year. Limited success with all the tricks with cleaners, ice, etc. Now have one with external sensors. Only three months old so, we'll see.
rondeb
Explorer
May 26, 2014
We had the exact same problem. 3/4 full and wouldn't budge. I tried everything(spent a fortune on vinegar and ice) We sat in LV for 2 winters (very hard water) so the hard water calcium built up was registering false readings. I got the gray tank cleared with hot water and vinegar, but when we got home, I decided I wanted the black reading empty. "These things bug me" I ordered

Black tank wand

It will bend into all corners of the tank. It took about 20 minutes of moving it into all corners and WAHLA tank read empty.

Definitely worth the trouble