Black tank

I've probably not gone more than a week without dumping.

But, I also do not clean my black tank or hose it out or any of the other heroic efforts I sometimes read about here. I always put an enzyme "poop packet" in the tank before a trip, and when I get ready to dump I have a small piece of wood that keeps the toilet valve blocked open so that I can top off the black tank with fresh water. Once it is full, I dump.

My RV is 28 years old, and I have owned it for about 10. The sensors operate great. In the day time you can see down the hole to the tank itself and while not "clean", you can see daylight through the holding tank walls.

I don't think there is any need to hose down or otherwise clean the black tank.

While using the RV or while in storage are very different answers. I would not leave fluids in the tank for extended periods while not using RV as the solids can settle and become stuck. I live in my RV with the DW and we have very large holding tanks and have been able to go for 3 weeks without dumping. It was REALLY full at that point and we really should have dumped sooner, but we did make it. A smaller coach or one not setup like the bus conversions are will not make it that long unless you are using some other bathroom facility throughout the day.

About 3 months, yes all summer and it was over half full. I drained it next time I picked it up from storage. The black tank is probably 99 percent liquid anyway, it will take a long time to evaporate up that 2 inch vent pipe.

7 DAYS MAX

the black tank is a holding tank only. the waste does not decay in a black like it does in a septic tank. do not get the two mixed up. BECAUSE if you do, you will have a 25 gallon brick and impossible to drain. and one other thing to know is do not ever, ever leave your black tank valve open when not dumping

During camping season I keep the trailer ready to go. When I come home, I back into the level spot, plug in the power, top off the water tank with fresh or change out completely, and make sure the drains have water in the traps and the toilet is holding water in the bowl. I sometimes have guests stay in the trailer until our next trip, and if they need water or toilet, it's no big deal. Usually camp once a month or more so the black tank never really sits more than a month with "stuff" in it. Plenty of water and the geo method have worked fine for me. I just dump at the next opportunity. Zero issues in 10 years.

I don't go by days. When it appears to be 3/4 or more full then I will dump it. We try to use a lot of water to make sure it drains well when we do dump which may mean we dump more often than many.

17 days, 2 people, 45 gal tank, RV bathroom exclusively.

The adhesive property of dried out poop is amazing. Even on something as slick as a porcelain toilet bowl. Simply wetting it doesn't remove much at all. It takes a pretty aggressive scrub to get the stuff off. I would suppose some sort of enzymatic action would have to take place to remove the stuff when there's no way to scrub or blast it off.

I start a trip with 3 gallons of water in the black tank and add at least a half gallon per flush of solids. Then I add 2 packets of dishwashing detergent to the tank at the start of the trip as well. Seeing as a dishwasher is able to remove stuck-on stuff with just water pressure, it's my theory that it will help in a black tank too. Gray tank for that matter as well, so I add 2 packets there too.

I would think it would take a long time to dry out.
I was wondering how long it would be before the waste would start to decay?