Black water flush

WALLEN · July 2025

I want to power flush the black water tank on my 2023 tab 400 but the water doesn't go into the tank when connected to a hose. Instead water leaks from somewhere under the trailer. The gauge indicating amount in the tack works fine. So something must be blocked? Should I sanitize the system agin?

Wyo4Life · August 2025

Does the Nautilus system levers need to be turned a certain configuration in order for the black tank flush fitting to be open? The only reason I ask is we just bought a 2025 Tab 400 last week and will need to know this in the future.

During our walk through I do not remember them saying anything about it to that level of detail but my rv'ing experience tells me you have a problem with that hose, possibly kinked etc.?

Will be interested to hear what you find out and what other more experienced Tab 400 owners have to say.

Sharon_is_SAM · August 2025

Found this: https://nucamprv.freshdesk.com/support/solutions/articles/44001867240-how-to-flush-the-black-tank

Sharon_is_SAM · August 2025

See qhumberd post in this thread: https://tab-rv.vanillacommunity.com/discussion/comment/215727#Comment_215727

subkron · August 2025

@Wyo4Life No, the nautilis system/levers only control the fresh water system, the black tank rinse is completely independent of that. There is pretty much a direct connection from the black hose fitting to the rinser on the black tank (there is a valve in-line but not adjustable).

Jay_and_Kat · August 2025

So something in the nuCamp video on flushing the tank I found interesting...
You leave the black valve closed while you're flushing then open to dump again. I've been keeping the black dump valve open when flushing (my usual dump station routine is: Dump black tank, flush black tank w/valve open, close black tank, open grey tank)

Have I been doing it wrong these couple years???

AnOldUR · August 2025

The nuCamp method kind of makes sense @Jay_and_Kat. The large volume exiting instead of just a steady stream may carry more waste with it. Like you, we've never done that in five years and haven't noticed it causing a problem.

What I do is after draining, I fill the bowl to the rim and flush several times with the gate still open. The toilet bowl holds about a gallon. My thought is that this large rush of fresh water from the bowl will help with flushing the black tank.

cottonmouth · August 2025

I do both. After draining the black tank, I run the rinse out with the gate open for a couple of minutes, and then close the gate to fill the tank and empty again. I haven't used a pressure regulator on the rinse port though. I just thought that since the system is open, there is no need for a pressure regulator. I haven't had any issues, but now I will start using a regulator.

Jay_and_Kat · August 2025

I'm thinking we've (so far) not had a problem as we can count on one hand the number of times we've used the toilet for...
"solid" waste (not including TP,) so there's not really a lot collecting in there to flush out.

Wyo4Life · August 2025

subkron said:

@Wyo4Life No, the nautilis system/levers only control the fresh water system, the black tank rinse is completely independent of that. There is pretty much a direct connection from the black hose fitting to the rinser on the black tank (there is a valve in-line but not adjustable).

Thank you, @subkron, I appreciate the information.

RogerY · September 2025

I made my own flush valve that connects to a standard garden hose. You can shove a 3/4 inch pipe straight down the black pipe and attach a plastic 3/4 female hose adaptor to it.

RogerY · September 2025

https://share.icloud.com/photos/0a1bQm6Jq6MRpZykAsPvie7vg

Black water flush

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