Black Water Pump Out Dilemma

[Bryant]

Black water pump out

For years, I've read the black water tank threads with a "lucky that's not me" mentality. Well, it looks like my turn has finally come.

Following Peggie's advice, I'm getting ready to ditch my black water vent filter and enlarge the hose including a nice mushroom through-hull fitting so my tank can breathe and I can ensure the vent is clear. In preparation, I went to the pump-out dock to empty my black water tank.

My black water tank is full (don't ask me how I know...it's not pretty). Nothing would pump out. What I tried:

Yes, the pump-out is working (at least it is vigorously sucking up seawater).

No, the vent is not clogged (well, it may have been but I disconnected it where it attaches at the top of the tank so there was no blockage before pumping).

Thinking the pump out line was plugged by solids at the entrance to the tank, I ran a plumbing snake down the deck fitting and "stirred things up."

Took it back to the pump out and still got nothing.

The kicker, I took the boat out (where it is legal) and the diaphragm pump allowed me to empty my tank overboard with no issues.

What in the world is going on here?

Most likely, the pipe that extends into the tank which allows you to pump out has probably corroded and has broken off up near the top of the fitting where it feeds into the tank. This is a common problem. You need a new pump out pipe installed. I had the same problem.

 

[isphh]

I had The same problem

I have a Nordhavn 40 and experienced the same problem. On my boat the solution was easy. After the y valve I have two vented loops for the two thru holes. One is for emptying the tank overboard and the other is for flushing directly overboard bypassing the tank. I had to tape over the vented loop for emptying the tank overboard. I remove the tape so that vented loop works when I want to empty the tank overboard with the macerator. Don't ask me why but I can now pump out my tank complete. BTW I replaced the little joker valves on the vented loops but still use the tape just in case.

 

[sndbowen]

On our way south this fall we had a problem with a pump-out. The pump-out would suck water from the bucket, but not from our holding tank. Turned out the dock pump-out hose had a crack in the plastic.

 

[Paramedic62]

I had the same problem, My tank was full but I could use a manual pump. It turned out that the steel reinforced black hose that was on the pumpout line from the tank to the deck fitting would internally collapse under vacuum. when snaked it was clear but when vacuum applied it would collape. we ended up pumping it out through a sender mounting hole on the tank top by making a wand from 1 1/4 plastic electrical conduit and a fitting that attached to the pump out ( i am on inland water way and cannot pump overboard ) found the problem only after a messy hose change

 

[Moonfish]

For ANYONE who has a holding tank system on their boat, we highly recommend (from first-hand experience) Forget About It:

https://youtu.be/lbf_s53OPzE

Everyone we talk to who has used it has basically the same reaction we did...

 

[Capt Ray]

All good comments. The only thought I can add is make sure you try from TWO or THREE different pump out stations before you go too far tearing apart your own system.

These pump out stations are maintenance intensive... and some places are more on top of the maintenance than others. I find a high amount of variability at our main marina's pump out station each week, it's irritatingly "hit or miss". It all depends upon when they last serviced THEIR equipment.

The next closest one to us is a mile away, and it is municipally owned/maintained. It too has a high level of variability of when it is working or not... or more accurately: working well or working poorly. This one has no attendant, it is self service. Interestingly, there is no sign with who to call if there is a malfunction. I wonder how they even know!

The THIRD place near us actually has a "green flag" and "red flag" system near the unit that essentially indicates if the pump out is even working or not!!!
(Same municipality - different location out on the beach/island/marina).

As I cruise around to different ports, I have always been impressed with the floating "honey pot" stations that come to one's boat to pump out, usually VHF73. For some reason, these guys' rigs are always in tip top condition, and have the best vacuum. Some even brag about it! These too are usually municipally owned. My guess: because the skipper is a FULL TIME, dedicated, PUMP OUT employee, he knows right away when there is a problem and calls for service.

 

[My1967nova]

We had a similar situation on our Sundowner 30 tug this past summer. Vent was open, ran a snake into the black water tank, but 2 different pumpouts would not pull a vacuum to empty the tank. Hummm.......

Found that the metal elbow between the tank and the pumpout hose had broken.

Fortunately the holding tank wasn't full.

Repaired the broken elbow and the tank emptied at the pumpout station.

 

[Ruffryder]

Use the threaded adapter to ensure tight seal.

 

[Glaukos]

I have had two similar experiences. The first was caused by a poor seal where the hose from the tank connects to the deck fitting. The second was caused by the top of the tank (an RV tank on a boat) caving in enough to allow the pump-out pipe (which was fastened to the top of the tank) to sit on the bottom of the tank, preventing it from sucking anything out. There were no notches in the bottom of the pipe so the pipe sealed against the bottom of the tank when the top of the tank sagged.

Richard Allen

 

[HeadMistress]

If you still have that boat and same problem, there's a easy cure for it.


--Peggie