Holding tank back flow to shower sump

[Nexterday]

2008 Amberjack 290. Holding tank 1/4 full. Cabin smelled, pulled the access panel and discovered about two inches of black water in the shower sump. Pumped out holding tank to confirm it wasn’t full (only about 1/4 as indicated). I rarely use the fresh water system for sinks/shower, just the head when guests are onboard. Looking for ideas on how the holding tank could backflow into the grey water sump. Thanks in advance

 

[Riptide III]

Are you sure it’s holding tank. That fresh water sump will get messy from lack of use. It will get a moldy nasty black film that smells

 

[Chris-380]

2008 Amberjack 290. Holding tank 1/4 full. Cabin smelled, pulled the access panel and discovered about two inches of black water in the shower sump. Pumped out holding tank to confirm it wasn’t full (only about 1/4 as indicated). I rarely use the fresh water system for sinks/shower, just the head when guests are onboard. Looking for ideas on how the holding tank could backflow into the grey water sump. Thanks in advance

It’s not from the holding tank, that’s what happens if the water gets stagnant and does not get treated. I put a little no flex in there every so often to help with that

 

[garybly]

Doesn't the shower sump pump overboard? It does on my 320

 

[K-DUB]

Searay offered a gray water option (environmental thing) where the sinks and shower sump drain/pump into the holding tank. My friend had it in his 26. If that’s the case then maybe an additional check valve in the sump discharge line or replumb it to pump overboard like most boats do.
Otherwise, it’s just stagnant water like the suggestions above. I throw a white toilet bleach tab in mine once a year and it keeps them clean and fresh.

 

[Lazy Daze]

As mentioned, that's not from the black water tank. There's no way that could happen. Not even with a grey water system (although good thought). A grey water system enters the black tank from the top.

Clean it out and disinfect the lines that dump into there. Clean it on a regular basis. Done.

 

[Nexterday]

Unfortunately, it is most definitely urine. Additionally, ran a test on Monday, flushing the head while monitoring the shower sump. Sure enough, the water came into the sump box

 

[Lazy Daze]

Hmmm. Go take a look at the black water tank - pay close attention to all of the hoses. If someone jury-rigged a grey water system, I wonder if they simply T'd into lines and you're getting some back splash. Post a bunch of pics if you need help.

And/or... we need confirmation if you do/do not have a a grey water system - or at least tell us if the sump box pumps through the hull?

 

[Nexterday]

Hmmm. Go take a look at the black water tank - pay close attention to all of the hoses. If someone jury-rigged a grey water system, I wonder if they simply T'd into lines and you're getting some back splash. Post a bunch of pics if you need help.

And/or... we need confirmation if you do/do not have a a grey water system - or at least tell us if the sump box pumps through the hull?

Thanks! Will eyeball it tomorrow.

 

[Nexterday]

I guess I overlooked the obvious. Black water hose from shower sump pump goes uphill (I guess to a tee in the head drain line). I pulled panels to look at lines
this is the sump with the shiny black hose.

next shot is the sump waste line going up to the main black waste line from the toilet. I am guess there is a partial blockage below the tee, and it backs up then flows down through the pump. Pump failed and allowed it to pool in the plastic sump housing, and spill over. Will snake it tomorrow.
Thanks to all for the advice and suggestions.

 

[Lazy Daze]

I guess I overlooked the obvious. Black water hose from shower sump pump goes uphill (I guess to a tee in the head drain line). I pulled panels to look at lines
this is the sump with the shiny black hose.

next shot is the sump waste line going up to the main black waste line from the toilet. I am guess there is a partial blockage below the tee, and it backs up then flows down through the pump. Pump failed and allowed it to pool in the plastic sump housing, and spill over. Will snake it tomorrow.
Thanks to all for the advice and suggestions.

Negative, Ghostrider, that is not how it should be plumbed. I think you're confused on some things...

The shiny black hose should go direct to the thru-hull for overboard discharge or direct to the black water tank (if you have a grey water system... still need confirmation).

Why not confirm if you have a grey water system or not? Just pour water into the head drain until the pump kicks on... does it come out the side of the boat or go into the black water tank? It seems like this would be an easy thing to do to make it easier for us to help you.

The head drain line feeds directly into the sump box. It would not be logical to drain into the DISCHARGE of the pump.

Your second picture DOES NOT show the sump discharge T-ing into the head discharge hose.

This is all assuming you don't have some type of home-brew installation... in which case, all bets are off.