When is black tank full?

rkymntsno · 07-17-2019, 08:09 AM

When it shoots out the roof vent, lol! I know there's a lot of discussion on this topic out there but I wanted to ask this forum the question. I have a 50 gallon black tank on our 355. This trip, it's just me and my wife. How do I know when it's time to dump the black tank so I don't empty too soon or too late? This size tank with two people, is 7 days realistic? I've heard of the "toilet burp" but not sure what that is. Are there pitfalls to waiting too long to dump? Is it safe to say if you can see the level coming up to the bottom of the toilet it's time to dump? Just trying to find out the best info for this. Thanks!

spoon059 · 07-17-2019, 08:15 AM

Its hard to say for certain, but my wife and I can survive 7 days on our black tank. Its usually the gray that fills up first. You'll be able to see down the toilet drain when the water is really high and starting to back up into the drain. I'd prefer to dump it BEFORE it comes back up the drain, because I don't have much faith in the seal at the floor line.

rkymntsno · 07-17-2019, 08:20 AM

Quote:

Originally Posted by spoon059

Its hard to say for certain, but my wife and I can survive 7 days on our black tank. Its usually the gray that fills up first. You'll be able to see down the toilet drain when the water is really high and starting to back up into the drain. I'd prefer to dump it BEFORE it comes back up the drain, because I don't have much faith in the seal at the floor line.

Thanks, that's what I was thinking. As far as the gray tanks go, our Open Range TT could only last 3 days before the overflow started. First time it happened I didn't know what it was but figured it out. Do all gray tanks have overflows? I've come to distrust all sensors now.

ynpmoose · 07-17-2019, 08:26 AM

I usually dump black if it hits 2/3rds on the sensor, just to be safe. That size tank will probably last 2 weeks with 2 people. I have my wife and 4 kids and we've gone 5 days on a 35 gallon black tank.

**norty1** · 07-17-2019, 08:28 AM

In our rig after 5-6 days, we will see and hear a bubble when the commode is flushed. That indicates to us that dump time is near. I think it gets full enough to cover the roof vent pipe in the tank which causes the indication of burping.

Screwby · 07-17-2019, 08:56 AM

Same here, I’ve waited so long it was visibly getting full, but usually if it’s burping I’m dumping it.

spoon059 · 07-17-2019, 08:59 AM

Quote:

Originally Posted by rkymntsno

Thanks, that's what I was thinking. As far as the gray tanks go, our Open Range TT could only last 3 days before the overflow started. First time it happened I didn't know what it was but figured it out. Do all gray tanks have overflows? I've come to distrust all sensors now.

Gray tanks should NOT have overflows. It is considered dirty water and you can't dump that on the ground.

Camper_bob · 07-17-2019, 09:18 AM

Quote:

Originally Posted by spoon059

Gray tanks should NOT have overflows. It is considered dirty water and you can't dump that on the ground.

+1 Gray will usually back up in the shower (lowest drain).

We're usually not out long enough to fill the black tank even enough to dump it. So I always end up having to put a bunch of water in so I can dump the tank.

And that's with 35 gallon tank and 2 adults and a child. I think 7 days is more than realistic (for us) on a 50 gallon tank.

In the rare event that we're in the rig long enough to fill the tank, I will usually dump it when the water gets to about an inch below the outlet as seen from inside the toilet. I have had it "burp" before, but in that case, I was actually TRYING to get it full.

**Mustang65** · 07-17-2019, 10:12 AM

Quote:

Originally Posted by rkymntsno

When it shoots out the roof vent, lol!.....

Check on the 1st post in this thread. That is a disaster.

https://www.jaycoowners.com/forums/f...r-61109-2.html

Don
My Registry

RVing with SOLAR

travelingjw · 07-17-2019, 12:07 PM

The most basic way to check if it is full is to shut off the water and shine a flashlight down into the tank. With 7 people, my guess is it will fill quick. I would rather empty early than deal with even one night where I was concerned that the tank would overflow.

**Midnightmoon** · 07-17-2019, 12:38 PM

I this heat, I end up dumping long before we have to just because of the smell. I really need to revisit our chemical selections or something, but this year has been really bad.

NewBlackDak · 07-17-2019, 01:29 PM

We were out for 5 nights with 2 adults + 4 kids, and my 35G wasn’t full. I added a ton of water to it before emptying.

GAD36H · 07-17-2019, 03:11 PM

I know when it's time to dump the gray tank when the wife hollers from the shower :-)

AKRUEBBE · 07-17-2019, 03:39 PM

Quote:

Originally Posted by GAD36H

I know when it's time to dump the gray tank when the wife hollers from the shower :-)

I know the feeling............the other day my wife was taking a shower and yelled, "the shower is not draining". Didn't think I could move so quickly

Salliemeandering · 07-18-2019, 07:45 AM

Midnight moon
I had that problem and discovered it was the grey tank. Overtime the smallest bits of food started stinking.
I also switched to a product called "break up" out of TX and have been very happy with it!

**Midnightmoon** · 07-18-2019, 07:47 AM

Quote:

Originally Posted by Salliemeandering

Midnight moon
I had that problem and discovered it was the grey tank. Overtime the smallest bits of food started stinking.
I also switched to a product called "break up" out of TX and have been very happy with it!

Thanks. I'll take a look at that product.

rkymntsno · 07-18-2019, 08:00 AM

Quote:

Originally Posted by Midnightmoon

I this heat, I end up dumping long before we have to just because of the smell. I really need to revisit our chemical selections or something, but this year has been really bad.

I know, us too. We tried RV Digest It. It sucks. Started stinking to high heaven after three days. I think I'm gonna switch to Rid X drop ins. Right now we're using TST Citrus drop ins and they seem to be working ok. So after four days, had to dump black with the smell. A 50 gallon black tank doesn't seem right. Gotta find some chemicals that'll work.

RetiredOne · 07-18-2019, 08:13 AM

Quote:

When is black tank full?

This is such an easy question to answer...When you need to wear one of these to move from the front to the rear of the coach!!

oh355mbqs · 07-18-2019, 09:05 AM

Hi rkymntsno,

We have a 355 also. I don't think you want to wait until the black water is backed up to the toilet. Since this is a 5th wheel and the bathroom is on the higher floor level, there is a drain pipe from the toilet to the tank. As someone pointed out earlier, I wouldn't trust the seal between the pipe and the tank. I can't remember for sure, but I think there was an offset in the pipe too (a couple of 45 elbows) so I don't think you can use a flashlight to see in the tank. If I have a full hookup, I just dump it whenever I think it needs it and then add more water chemicals. I kinda go by the sensors, but don't trust them too much.

rkymntsno · 07-18-2019, 09:20 AM

Quote:

Originally Posted by oh355mbqs

Hi rkymntsno,

We have a 355 also. I don't think you want to wait until the black water is backed up to the toilet. Since this is a 5th wheel and the bathroom is on the higher floor level, there is a drain pipe from the toilet to the tank. As someone pointed out earlier, I wouldn't trust the seal between the pipe and the tank. I can't remember for sure, but I think there was an offset in the pipe too (a couple of 45 elbows) so I don't think you can use a flashlight to see in the tank. If I have a full hookup, I just dump it whenever I think it needs it and then add more water chemicals. I kinda go by the sensors, but don't trust them too much.

Yes, I looked down there yesterday and saw what I thought was an elbow and thought that was strange. So thanks for that. We had to dump yesterday, leaving Friday so I'll add plenty of water when I dump tomorrow.

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