Adding a valve to the black tank outlet

[Hayden Watson]

I am looking for feedback on my plan and suggestions for sanitation fittings. FWIW, I also have a motorhome and have concidered using a Valterra gate valve like is used for the dump on my RV.

The factory installed plumbing for the black tank is all PVC. Starting at the tank outlet, there is a 1½" nipple to one arm of a 1½" tee. The pumpout is connected to a barb on the other arm. The macerator is screwed into the stem of the tee. several years ago, I had complete pump failure where the rods that connect the macerator pump head to the motor which dumped the contents of the black tank into the bilge.

I obviously never want that to happen again so I would like to add one or two valves to the system. I would like to have a valve between the tee and the macerator so that I can flush it out after a cruise and then isolate it from black tank contents. I sail in the Salish Sea and in the US waters, overboard discharge is totally illegal. I can only use it when up in Canadian waters so most of the time I want it in cold storage. I figure that after a CA cruise, I will pump down and flush before leaving Canada and then close the valve. Then after I am back at the dock, I will do a more through flush of the tank at the pump out to get the tank completely clear. Then I can put some pet safe antifreeze with anti-corrosion additives into the tank and run that through the macerator. Then my closing the thru hull and valve on the tee, I can keep the macerator in a clean and protected state until next needed for a cruise to CA waters.

I would also like to put another of the gate valves between the tank and the tee so that I can use flush hose at the pump out for rinsing the macerator and also as an emergency shut off in case the new macerator ever comes apart again to make it easier to replace.

 

[jssailem]

A couple of questions.

• The RV valve makes me cringe if it is to stop raw water from entering the boat. I have seen those valves on RVs dribbling a bit of tank water as they drive down the interstate. I suspect you plan to use a standard through-hull valve to ensure that raw water is stopped at the hull. The RV valve would be between the through-hull valve and the tank. Not sure what will happen if something gets clogged on the lip of that vertical gate.
• Reading @Peggie Hall HeadMistress information, she suggests that there is no need for a macerator as the toilet paper and human waste become dissolved in water when aged in the holding tank for a couple of days. You just need to manage what goes into the tank.
• I have installed a Whale Gulper Toilet/Waste Pump, 12V to evacuate the effluent from the holding tank in open waters.
  • Ideal for emptying holding tanks and vacuum systems.
    • Non-choke valves are virtually unblockable
    • Can run dry without damage
    • No air locks - can pumps air/water mixture
    • Large single diaphragm pumps up to 18 litres (4.75 US gal) per minute
    • Rotatable head allows flexibility when installing in awkward locations
    • Self priming up to 3m (10 ft.)

You will need to have a way to show that the pump over the side plumbing is locked while in controlled waters.

 

[Hayden Watson]

A couple of questions.

• The RV valve makes me cringe if it is to stop raw water from entering the boat. I have seen those valves on RVs dribbling a bit of tank water as they drive down the interstate. I suspect you plan to use a standard through-hull valve to ensure that raw water is stopped at the hull. The RV valve would be between the through-hull valve and the tank. Not sure what will happen if something gets clogged on the lip of that vertical gate.
• Reading @Peggie Hall HeadMistress information, she suggests that there is no need for a macerator as the toilet paper and human waste become dissolved in water when aged in the holding tank for a couple of days. You just need to manage what goes into the tank.
• I have installed a Whale Gulper Toilet/Waste Pump, 12V to evacuate the effluent from the holding tank in open waters. View attachment 237949
  • Ideal for emptying holding tanks and vacuum systems.
    • Non-choke valves are virtually unblockable
    • Can run dry without damage
    • No air locks - can pumps air/water mixture
    • Large single diaphragm pumps up to 18 litres (4.75 US gal) per minute
    • Rotatable head allows flexibility when installing in awkward locations
    • Self priming up to 3m (10 ft.)

You will need to have a way to show that the pump over the side plumbing is locked while in controlled waters.

• RV 1½" gate valve would go between the tee from the tank and the macerator. The outlet from the macerator is a 1" hose and it would go to a standard Series 93 Marelon seacock.
• Good point. I use Norflex Digester and it does an excellent job of breaking down the solids.
• I will look at that pump. My understanding is that removing the handle on the valves is sufficient for the no discharge rule.

 

[jssailem]

The CG was giving away large Orange Zipties to secure the valves on the boat at the Seattle Boat Show. Of course, you can remove a ziptie, but if in place during the inspection, all is good.

 

[Hayden Watson]

I was looking through the offering of non-macerator pumps and came across this one. My black tank is only 18 gallons so this would take less than 2-minutes of pumping. It says that is it rated for waste.

 

[Stu Jackson]

Hayden, IIRC there's not a whole lot of room where your existing macerator pump is located. Unless it's a Shurflo unit, it WILL lock up on you. ALL of the Jabsco units lock up. Shurflo just does it less often..

Your suggestion takes oodles of room. And is manual.

John's suggestion, which he's proven in practice, is far superior and would be my choice. Would be, too, if I got rid of my old macerator pump. It's a Shurflo, in since 2013, about due...

 

[Hayden Watson]

Hayden, IIRC there's not a whole lot of room where your existing macerator pump is located. Unless it's a Shurflo unit, it WILL lock up on you. ALL of the Jabsco units lock up. Shurflo just does it less often..

Your suggestion takes oodles of room. And is manual.

John's suggestion, which he's proven in practice, is far superior and would be my choice. Would be, too, if I got rid of my old macerator pump. It's a Shurflo, in since 2013, about due...

It will NOT be a Jobsco pump. My last one was a Jobsco and I wish that its only problem was that it locked up. The rods that hold the pump head to the motor rusted away and the head fell off, dumping about 1/4 of a tank of black water into the bilge. I do not ever want to repeat that again. Oh, and of course, it happened on a day we had guests on board.

I am leaning toward a manual diaphragm pump.

 

[jssailem]

Certainly, the Gusher Urchin is an option. I have one on my boat as a manual bilge pump. Works great for liquid overboard disposal.

Only issue I find yucky:
• Quick access of diaphragm for removing debris
The challenge of a diaphragm pump is the potential for blocking. Liquid effluent will pump out fine.

Perhaps that is all you need while cruising north of the 49th parallel.

 

[colemj]

Big no on a macerator pump and a big yes on the whale pump John listed. I think that thing will pass a tennis ball if you can.

Macerator pumps are for masochists.

I've never had to access the diaphragm because ours has never clogged or got enough debris to overcome the check valves. I guess that is a concern, but no different than an issue with a macerator, as far as yuck goes.

The manual pump you linked is the same as the one John showed in how they operate. They are both diaphragm pumps, only one uses a motor to operate the diaphragm. There may be differences in size and stroke capacity - I didn't look closely. I think the Whale will be slower than the macerator, but that isn't really an issue.

Mark

 

[JoeWhite]

Hayden, you are on the right track, but...., I experienced that very same problem with the macerator pump with broken screw rods. They broke because it's head potion twisted as the hull twisted and it was connected to the holding tank with a PVC T divider. I fixed it by installing stainless steel screw rods cut to size, and to allow flexing I added a 4" sanitation hose. I also installed bronze 3-way ball valve to direct the content to the macerator or to the pumpout hose and installed 4" hoses on all sides of the 3-way valve to allow flexing. This will also prevent the content of the holding tank from spilling out if the macerator breaks, since it is normally in pumpout position.
Check my website for additional content and images.

Macerator Pump | Sail La Vie

mei1970.org

 

[MikeHoncho]

It will NOT be a Jobsco pump. My last one was a Jobsco and I wish that its only problem was that it locked up. The rods that hold the pump head to the motor rusted away and the head fell off, dumping about 1/4 of a tank of black water into the bilge. I do not ever want to repeat that again. Oh, and of course, it happened on a day we had guests on board.

I am leaning toward a manual diaphragm pump.

The gusher diaphragm pumps will transmit smell like cheap hoses do over time. I had one for my pump-out, set higher than the tank, so it wasn't full all the time, and it still stank when I cut it all out for a Desiccant toilet.