Black tank level estimate options

[oldryder]

Grand Design 27RL new to us. Everything worked (!) except black tank level indicator which shows full. I am aware this is a typical problem. is there a reasonably convenient way to measure fill level manually?

 

[Ex-Calif]

I can see the level of the tank through the toilet if I look. I also have gotten decent at estimating the time between dumps needed - Usually a week to ten days if solo.

I can also "hear" the relative level by the splash sound when flushing.

But TBH when living aboard I just dumped every 7 days or so. I didn't earn any prizes by filling to the brim before dumping.

 

[Mark_K5LXP]

I didn't earn any prizes by filling to the brim

I thought that was something everyone got a trophy for.



Mark B.
Albuquerque, NM

 

[Oldgator73]

I never trusted the level indicators. I just dumped every three or four days.

 

[Mark_K5LXP]

is there a reasonably convenient way to measure fill level manually?

Generally you can go by your fresh tank level. Unless you disproportionally use the sinks & shower vs the toilet you can gauge the full-ness of black and gray by the empty-ness of the fresh tank.

My level indicators have worked reliably since I got the thing but as the old RV'er Ron Reagan once said , "trust but verify". One fine day I spent some quality time with a 5 gallon bucket and a hose, and proceeded to fill each tank with a measured amount to compare to what the gauges said. Turns out I have 10 gallons left in the fresh tank when it says "E" and I have 5 gallons remaining when the black tank says "F". Per Ex-Calif's post you can "tell" by the sound when you're getting close to full. Once you see the level starting to come up the toilet drain through the slide valve you know you're done. My bathroom sink drains into the black tank and just by running the faucet a second then listening to it dribble into the tank I know I've either got room to spare or better start being quicker on the flush pedal.

Mark B.
Albuquerque, NM

 

[Tulecreeper]

Generally you can go by your fresh tank level. Unless you disproportionally use the sinks & shower vs the toilet you can gauge the full-ness of black and gray by the empty-ness of the fresh tank.

My level indicators have worked reliably since I got the thing but as the old RV'er Ron Reagan once said , "trust but verify". One fine day I spent some quality time with a 5 gallon bucket and a hose, and proceeded to fill each tank with a measured amount to compare to what the gauges said. Turns out I have 10 gallons left in the fresh tank when it says "E" and I have 5 gallons remaining when the black tank says "F". Per Ex-Calif's post you can "tell" by the sound when you're getting close to full. Once you see the level starting to come up the toilet drain through the slide valve you know you're done. My bathroom sink drains into the black tank and just by running the faucet a second then listening to it dribble into the tank I know I've either got room to spare or better start being quicker on the flush pedal.

Mark B.
Albuquerque, NM

Unless you take nothing but Navy showers, those two won't have much to do with each other. If I'm hooked up to city water, I'm taking a regular shower. The average shower lasts about eight minutes. Since the average showerhead has a water flow of 2.1 gallons per minute, each shower uses more 16.8 gallons of water. Three such showers and my gray tank would be full with shower water alone, not counting washing dishes, etc.

Flushing the toilet only uses about a half gallon.

 

[Mark_K5LXP]

I would consider long showers "disproportionate use", because if you're not on hookups one generally doesn't invite burning through their fresh water supply taking showers. Odds are it will never be perfectly even but between conservative use and the size of the gray and black vs fresh, you may not fill either one completely. I've got about 80 gallons combined waste vs 60 gallons fresh so it would take a fairly significant use imbalance to fill just one completely. I got one of those drain fittings with a blade valve on it with the idea I could put that on, open the gray and black tanks to let them equalize in the event one filled before the other. Now years later I've never had the occasion to use it. Very user dependent for sure, but there's quite a bit of margin there at least with my setup.

Mark B.
Albuquerque, NM

 

[CharlesinGA]

Dan has the right idea, if the toilet sits on the tank, just stand on the pedal and take a light and look down in it.

One thing you need to determine is if the bathroom sink(s) drain into the black tank or the gray tank. Winnebago motorized RV's in almost every case, adds water to the black tank by draining the bathroom sink into it. Great idea. Other companies do this only if its convenient and they feel like running the pipes that way.

Charles

 

[LarsMac]

Dan has the right idea, if the toilet sits on the tank, just stand on the pedal and take a light and look down in it.

...

Charles

My toilet has an angled pipe to the tank, so can't see into the black tank. About all I can do is guesstimate how full it is getting. but dumping about every three or four days has proved safe, so far.

 

[MoInEd]

I have the toilet right above the tank and look as sometimes the sensors are not reading correctly.
O thing I am not sure is how fr below the toilet connection is full

 

[Kirk]

O thing I am not sure is how fr below the toilet connection is full

Take a look at the black tank and measure the height of it and then add something for the distance from the top of the tank to the toilet flush valve. Depending on what RV you have, the distance between the bottom of the toilet and the top of the tank is usually only about 6" but you should be able to see what it is right after you dump the black tank by using a flashlight.