PVC Valve Safe Between Holding Tank & Macerator?

[P12nash]

I'm in the midst of replacing all of my sanitation hoses with Raritan Saniflex and installing a Raritan Marine Elegance head. One major issue with the original design of the sanitation system on my Hunter 38 is that the discharge on the holding tank for the macerator is at the bottom of the tank, has a 12' run of hose, and then goes to a valve and macerator. I'd like to add an additional valve at the tank fitting so that I can prevent that hose from constantly being full of sewage. Is it safe for me to use a standard PVC ball valve in this application, or should I be purchasing a marine grade bronze or marelon valve?

Thanks

 

[Peggie Hall HeadMistress]

Hopefully you haven't run any of the tank discharge plumbing yet 'cuz there are betterways to accomplish what you want to acccomplish without the need for ANY inline ball valves.

I have questions that need answers before I can recommend a plan: You don't mention any pumpout line...surely there is one. Is the discharge fitting for the macerator pump separate from the fitting for the pumpout line or does the line to the macerator pump tee into the pumpout line? If--as I suspect--it tees into the pumpout line, is that connection just a tee fitting, or is it a y-valve?

How much clearance do you have above the tank?

--Peggie

 

[P12nash]

Hi Peggie,

Right now I just have all of the lines run where the previous ones were, but nothing is cut to length or connected yet.

My pump out is connected to a dip tube that is in the top of the tank. There is a short section of hose between that and the fitting above - about 1’.

The discharge for the macerator is on the side of the tank right at the bottom. A 1-1/2” hose runs from there to the macerator under the aft berth sole. From there a 1” hose goes to the thru hull in front of the companionway steps. All of my below the waterline thruhulls are centrally located there.

I currently do not have a y valve.

If memory serves correctly I have about 10-16” of clearance above the tank that provides access to 1/2 of the top surface. This requires me to disassemble some of the aft berth.

 

[Peggie Hall HeadMistress]

Unless you plan to do a lot of open ocean sailing in the very near future, you have very little need for a macerator pump (see the EPA list of NDZs by state to see how much of the east coast waters from Maine to LIS are NDZs EPA NDZ list and besides you have to be in open sea at least 3 miles from the nearest point of land on the whole US coastline dump a tank legally, so you wouldn't be able to dump a tank in any of those waters anyway. If you actually do any blue water sailing, install a y-valve in the toilet discharge to discharge the toilet directly overboard at sea.

So I'd simplify the plumbing by getting rid of the macerator and its related plumbing altogether...a threaded plug wrapped in plenty of Teflon tape will seal the tank discharge fitting.

That's my $.02 worth anyway...your mileage may vary.

----Peggie

 

[Rick Webb]

I'm curious on the point of the question.

Is a PVC ball valve acceptable??

 

[Peggie Hall HeadMistress]

Schedule 40 PVC might be a bit brittle in cold weather, but schedule 80 is ok. I just can't think of a good reason to use one in the OP's plumbing. If he's determined to keep the macerator pump, a PVC shutoff valve at the tank would be a much better choice.

What y'all may not realize is that lack of use for extended periods is more damaging to equipment than heavy use because rubber parts (gaskets, etc) dry out and leak, lubrication in sealed motors settles to the bottom, no longer providing any protection from corrosion, and unless a macerator pump is thoroughly rinsed out after use, the impeller sticks to the housing, resulting in a cracked vane the next time you try to use it.
All of which should explain why I recommend he just remove it and either install a new one if/when he can use it or just plumb to flush overboard at sea instead of unnecessarily flushing into the tank.

--Peggie

 

[P12nash]

Hi Peggie,

I do a lot of day sailing but also have an annual 7-10 day cruise and do many weekend cruises throughout the season. While there are a lot of no discharge zones in my cruising territory, I prefer to keep the macerator so it can be used to aid in flushing out my tank or empty it offshore during my longer cruise. I actually chose the sea fresh option for my Raritan elegance so that it could be used in conjunction with the macerator for clean out of the holding tank.

I appreciate your input and time. PS I have a copy of your book which has encouraged and informed the overhaul of my sanitary system. It’s a great resource for boaters.

 

[Peggie Hall HeadMistress]

As long as you understand that it's not only in NDZs that it's illegal to dump a tank or flush directly overboard, it's illegal in all US waters within 3 miles of the US coastline. The Chesapeake Bay is an example. There's only one small NDZ--Herring Bay--in the whole Bay...the discharge of TREATED waste from a USCG certified Type I or II treatment device (ElectroScan or PuraSan) is legal, but dumping or direct discharge is not.

If you still want to keep the macerator, I'd get rid of both of the ball valves--the one you have and the one you wanted to install--and put a shutoff valve in that discharge line at the tank.

Plan B 1.0 : relocate the macerator pump to put it above the tank, or at least at the top of the tank. Use a 90 degree tank fitting and run the line up to the macerator pump. This will eliminate the need for a shutoff valve at the tank and give you a downhill run all the way to the thru-hull, eliminating standing sewage in the line from the macerator pump. You'd still have standing sewage in the line from the tank fitting to the level in the tank ...if you weren't using SaniFlex hose, I'd recommend that you use hard PVC to the top of the tank, then switch to hose...wouldn't hurt to do that anyway.

Plan B 1.2 : Relocate the macerator as described in Plan B 1.0, and put a y-valve in the pumpout line. A threaded plug wrapped in plenty of Teflon tape will seal the lower tank fitting.

Plan B 1.0 and 1.2 are submitted for your consideration without actually seeing the sanitation system on your boat, only going on your description of it.

--Peggie

 

[shemandr]

I never understood the design of the Hunter 356 macerator system for the very reason the OP states. Since there is not a shutoff at the tank the hose is almost always full of sewage and I think that hose is more prone to permeation than the other side of the system. Based on Peggie's book I wanted to add a shutoff valve but didn't before I sold the boat.
The J valve and tank plug seems to be a viable solution without the macerator problems (And there are some). Even with a tank shutoff for the macerator there would still be sewage in the macerator hose. I don't know of a simple way to drain it.
If you want to clean the tank you can flush it with fresh water after a pump out and re-pump out the less-
fresh water. Repeat.

 

[sailme88]

I did a complete overhaul of my system a few years ago after the macerating pump failed. I had the tank vac'ed and then carefully removed the tank.. While out, totally rinsed out the tank to remove the old settled sludge. I went to a PVC specific store and acquired my needs in the gray sewerage rated PVC. Out of the tank. a close nipple connects the tank to a gate valve. The valve has a close nipple that attaches to union joint. The new macerator is fed from the union by a rubber black water rated hose. This isolates the tank.. Should the pump fail, the union is opened and the pump easily removed with about a cup of black water spilling into a disposable aluminum foil cooking pan that just fits under the joint. CG inspection by the MSO found the installation above and beyond and commented on the efficiency of the set up..

 

[JamesG161]

I actually chose the sea fresh option for my Raritan elegance so that it could be used in conjunction with the macerator for clean out of the holding tank.

Another method we use [in proper zone] to clean out holding tank.
1} Macerator and dump.
2) Leave the hull isolation valve OPEN.
3) Let the sea water back flow and fill up your Hold tank [ takes us about 15 minutes to back fill tank]
4) Macerator and dump again.
5) Repeat steps 3 and 4 again.
6) Close the isolation Valve.

Hold Tank is cleaned!

Note this works when your hold tank top is below your boat water line.
Jim...