How often and how to clean black tank

rvshrinker wrote:
We have sani flushed the tank only once in 3 years. Recently I read I should be doing this more often. On the other hand some places say not to empty black too often because then there is an inadequate amount to drive biodecomposition. It does smell now despite minimal use so I'm planning to flush.

Also I read to 1. Empty tanks. 2. Fill with some toilet flushes. 3. Add some bleach and dish soap. 4. Let sit. 5. Empty. 6. Leave black tank open. 7. Flush for a while (how long?). 8. Close up. 9. Flush some water into toilet.

We use the rv for 3-6 4-16 day trips per year. And occasionally at home as a spare bedroom or office. In The latter cases, if it makes sense to avoid using the toilet we could easily do this.

I drain and flush the black tank on our TT after every trip. Then I fill the black tank with water and a big dollop (1/2 - 1 cup) of bleach, let it sit about an hour, then drain it again.

We go weeks or months between trips, so the camper is just sitting. If the black tank isn't thoroughly rinsed out and sanitized it will stink up the camper.

We used to camp a lot with 2 other families, brothers, who own a septic / excavation company. When they bought new campers, they insisted that people were wasting their time flushing black tanks, as they were experts and knew that the "stuff" in the black tank would biodegrade and not smell. I just shrugged my shoulders.

Next camping trip they said that their shop where they store their campers stank to high heaven, and they sheepishly said "yea, the campers don't have septic tanks but holding tanks that need to be cleaned".