# Installing a macerator pump



## Omatako (Sep 14, 2003)

My boat has two heads, both with bag-type black water tanks, neither has any way other than vacuum pump-out to empty them. So I have started installing macerator pumps on both, actually the one installation is pretty much done. But is was a heck of a job and I'm not looking forward to undoing any of it.

This is how I piped the thing up:








In reality the only changes are the pipes to and from the new pump and the Y fittings into the vacuum pipe and into the seacock discharge line. The "heck of a job" included a complete re-pipe and a new Y valve.

In a quick test it seemed to work OK but I wondered whether I need any one-way valving to stop unwanted "stuff" appearing in the bowl? For example, a few barnacles in the skin fitting and enough pressure could result to push back up the yellow line into the head. My guess is switching the Y valve would deal to that but what if someone forgot to do that? 

Another thing that I discovered in the quick test is that the exit fitting from the bag is not at the bottom and as soon as the level in the bag (I filled it with water to test) drops to this fitting, the pump starts to cavitate which with these pumps is a no-no. That means a significant percentage of the contents will not be pumped and will lie in the bottom of the tank.  The vacuum units draw everything out, flattening the bag in the process.

I also noticed that when the pump ran and the level got down to the exit fitting, the back "skin" of bag was drawn onto the fitting effectively blocking it off. I wondered whether repositioning the bag to stop this happening would help the pump get more contents out.

Any comments?

Andre


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## theartfuldodger (Sep 4, 2006)

Have a question in each head where does the sink drain straight out the hull, you are probably wondering why I'm asking this, but depending on your answer, may have a very simple fix for you


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## Ilenart (Jul 23, 2007)

*What a crappy post!*

Omatako,

one thing I would suggest is be careful in leaving liquid in the bag. I have a similar system I installed last year (without the Y valve) & I am having problems emptying the bag completely. Lately there is a smell coming from this compartment and I cannot locate any leaks in the system . So I am wondering if the smell is coming out of the bag. What I am going to try in future is to flush the bag a couple of times before I leave the boat for extended periods so any liquid remaining is mostly sea water.

I also have the same problem when the bags almost empty that the back skin gets drawn in. A couple of times I have lifted the edge of the pipe when the pumps running and that sucks out a bit more.

My outlet fitting is on the right hand side so I normally empty the tank on a port tack, which means the outlet is the lowest point of the tank. This definitely helps in emptying the majority.

Overall I have not been too happy with the "bag type" tank and I am wondering whether a "hard type" tank would be a better option in the long run. However the bag type was significantly cheaper so I am persevering with fine tuning "the system"!

One thing I noted on your diagram is no water inlet. Assume you have a saltwater inlet not shown?


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## sailingdog (Mar 19, 2006)

One change I'd make to your system, to both simplify the plumbing and to make it more reliable is to eliminate the diverter valve and have the head pump directly into the holding tank. When you're out past the three-mile limit, you can always empty the holding tank instead of pumping the head directly overboard, so you're really not losing any capacity. 

I would then put the diverter valve, which you removed from the head output line, in the holding tank output line, where you have the "Y". If you ever have to work on the macerator pump, having this diverter valve will make your life a lot simpler and help keep the mess to a minimum.


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## Rodz47 (Apr 2, 2006)

I am looking at the drawing and trying to understand the rationale behind putting the vent line together with a drain? I am not a plumber but for me it looks like your pump will be sucking air not sh...t. It sounds like cavitation also. Wouldn't be better if you install your vent in the upper portion of the tank??

Just a thought!


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## sailingdog (Mar 19, 2006)

He said deck vent, he meant deck pumpout fitting. 


Rodz47 said:


> I am looking at the drawing and trying to understand the rationale behind putting the vent line together with a drain? I am not a plumber but for me it looks like your pump will be sucking air not sh...t. It sounds like cavitation also. Wouldn't be better if you install your vent in the upper portion of the tank??
> 
> Just a thought!


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## artbyjody (Jan 4, 2008)

There is a decent illustration .. hope that helps.


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## brak (Jan 5, 2007)

Тhat's kinda how I have it except I don't have a Y-valve - just a regular Y crossing. Gotta keep the deck fitting properly closed when using the macerator, but it does seem to work well even that way (less than 3 minutes to empty over 30 gallons of liquid in a tank).


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## Omatako (Sep 14, 2003)

Let me respond one at a time:

Brak - the Y valve allows me to positively direct the black water where I want it. As mentioned below, I don't want everything automatically directed to the tanks.

Jody/SD - the layout you have provided (thanks for that) is the same as suggested by SD inasmuch as everything pumps to the holding tank. That may be best in the US but "anywhere else" in the world, within a relatively close proximity to the shore you are allowed to pump macerated black (no solids) water to the sea. In NZ that limit is 500 metres. And especially when we're at sea proper, we rather pump black water directly to the sea and not to a holding tank. Hence the position of my Y valve.

SD - as far as being able to effect repairs without getting oneself immersed in black water, that's really a matter of wash, wash, wash before disassembling. I just did that and not too terrible.

Rodz47 - SD got in 1, that's where the pump-out connects and it is of course a good seal so no problem.

Ilenart - Yes leaving juice in the bag bothers me too. I've just replaced all the pipes because some of them were transmitting odours. I think that the bags will start to do the same after a time. I guess it will become a ritual of flushing the bags with volumes of water and pumping it out before leaving the boat. And, yes the water in isn't shown, that's really a given. I was more trying to debate the outlets. Solid tanks are just too big a job, I'd rather replace the bags periodically

Dodger - my basins drain through their own skin fittings but they're above the water line so not really a 1st choice for black water  . And besides, a backfeed into the basin would probably irritate my wife a little especially while she's cleaning her teeth  

One of my concerns is the back-feed and more I think about it the simplest solution would be to fit a joker valve into the yellow line (my diagram).

Thanks for responses, always valuable.

Andre


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## artbyjody (Jan 4, 2008)

Omatako said:


> Thanks for responses, always valuable.
> 
> Andre


In the states we are more stringent on how systems can hook up... Prior to - the regulation - a y-valve was ok prior to the holding tank to discharge overboard...hence why the drawings reflect the y-valve after the holding tank - it appeases the gods that inspect to make sure at least US vessels meet our laws for discharge of waste....having one prior to the tank and before the head - here in the states we are presumed guilty of not abiding by the rules...


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## maru657 (Aug 4, 2007)

The sanitation setup on my boat is almost exactly like yours. I think the odor problem can be fixed by using better piping. The piping I used was over 7$/ foot but seems to have eliminated the nasty smells. You can get this at west marine.


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## sailingdog (Mar 19, 2006)

The best hose for sanitation use is Sealand's OdorSafe hose... a bit pricey, and a royal pain in the butt to work with, but worth the extra effort and money IMHO.


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## chucklesR (Sep 17, 2007)

Heating the hose with a hairdryer makes it easier to bend.

Flushing the system with fresh water is probably the most effective way to reduce odor, my boat has plumbing that enables that. I'd rather waste a gallon here and there to flush a shot of fresh water through every day as part of my nightly close up/rounds than have a head that stank.

Melted ice is the easy source of flushing water.


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## sailingdog (Mar 19, 2006)

Chuckles-

Did PCI plumb the Gemini so you can flush the head from the Head compartment sink, like they did on my Telstar???

That really does get rid of a lot of the stink...since a good percentage of head smell is from rotting sea life, rather than permeated hoses... and new hoses don't stop that from happening...


chucklesR said:


> Heating the hose with a hairdryer makes it easier to bend.
> 
> Flushing the system with fresh water is probably the most effective way to reduce odor, my boat has plumbing that enables that. I'd rather waste a gallon here and there to flush a shot of fresh water through every day as part of my nightly close up/rounds than have a head that stank.
> 
> Melted ice is the easy source of flushing water.


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## Omatako (Sep 14, 2003)

maru657 said:


> The sanitation setup on my boat is almost exactly like yours. I think the odor problem can be fixed by using better piping. The piping I used was over 7$/ foot but seems to have eliminated the nasty smells. You can get this at west marine.


West Marine would be a little problematic for me, I live in Auckland. 

I have repiped the for'ard head with piping that I'm told is the same as that is used on the superyachts built in NZ. Costs NZ$34 a metre so not cheap. I reckon it'll probably do it, sure hope so because royal pain in the ass is right. So far that part of the boat is odour-free. Now for the aft head.

Chuck - I was wondering whether heating the pipe to make it more maleable will not cause a breakdown in the impervious properties of the pipe? I don't know, just wondered.

As said, I will need to get into the habit of laundering the system regularly to stop premature permanent contamination of the bags because I can't see a simple solution to the exit pipe not being at the bottom of the bag.

Andre


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## Ilenart (Jul 23, 2007)

Omatako,

the system I installed also uses the expensive anti odor piping & I am still getting smells out of the system, most probably from the bit that's left in the bag. I think ChucklesR is on the right track; flush out the system with fresh water. Note that I am only getting the smells after 1 or 2 weeks of pretty hot weather (36-38 degrees C for the last couple of days). Therefore giving the system a good flush before you leave the boat will probably suffice.


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## artbyjody (Jan 4, 2008)

Go with an airhead...


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## robfinora (Apr 25, 2001)

Andre -<o></o>
<o></o>
I am not crazy about your system going on here. I went through this drill 2x in 1 year because I did not do it right the first time - not a fun job and most marinas will shy away from this work. I tried to savage the collapsible bag system which did not work out in the end. A few things I noticed here are as follow:
<o></o><o></o>
- Your vent line is not really doing much. It needs to be mounted on a fitting located on the topside of the tank to allow fresh air in. In a collapsible bag system though - it totally defeats the purpose of allowing fresh air because the bag collapses on itself. A vent is very important as it also allows for natural decomposition and thus a major reduction in odor. That said, replace your collapsible tanks with a rigid plastic tank so your vent will actually do its job. You will eliminate a significant amount of odor.<o></o>
- Do away with the diverter valve coming off your bowl. Plumb directly to your tank. This is a dangerous point of failure for seawater to enter the boat when the diverter valve is positioned toward the seacock and the seacock is open. You are relying on a rubber joker valve on the head pump to hold back the sea!<o></o>
- Plumb your head sink drain line into the seawater intake line for the head with a "T" just above the seacock fitting - yes, do this. Now keep this seacock closed almost all the time. Use the head as you would - THEN wash your hands in the sink prior to flushing. The sink water will then sit in the drain line and sink because your duel-operating seacock is closed not allowing the sink water to drain or the head to take in seawater when you flush. Now, after your hands are clean and water is in the sink - Flush and the bowl will suck through the fresh, soapy water into the holding tank. This will significantly reduce head-odors as seawater is the one of the primary sources for head-odor (sea bacteria and critters cause most of the odor believe it or not).<o></o>
- Plumb your macerator pump into one exit line coming out of the plastic tank and just before the intake side of the pump - install your diverter valve running to the deck - pump-out.<o></o>
<o></o>
I am not an expert but I did research the heck out of this online when I went through the drill a few years ago. My system runs flawlessly and has virtually no odor emitted from any part of the lines, vents or tanks.<o></o>
<o></o>
Rob<o></o>


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## arf145 (Jul 25, 2007)

Rob, I'm interested in the sink water-to-toilet bowl deal, as I planned to flush with fresh water this year but would like to avoid having a water jug kicking around the head. Just so I'm clear: you run the water inlet to the toilet from a "T" just above the sink outlet seacock? Do you put a valve on the toilet line side of the "T" so water won't always be sitting in that line? And the normal seawater-inlet seacock is now a closed off dead end?


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## sailingdog (Mar 19, 2006)

Rob-

I have a very similar setup with the ability to flush the sink using water from the head compartment sink. It makes winterizing the head a lot simpler and really does cut down on the odors coming from the head.


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## Omatako (Sep 14, 2003)

Rob, you should really read the rest of this thread because if you had you would have known that:

<O></O><O></O>
- Your vent line is not really doing much. The vent line is actually the pump-out fitting on deck, not a breather.
- That said, replace your collapsible tanks with a rigid plastic tank In order to fit rigid tanks would require a redesign of my boat and I have no intention of doing that.
- Do away with the diverter valve coming off your bowl. Plumb directly to your tank. I stated a range of reason why I don't want to pump directly to the tank.<O></O>
- Plumb your head sink drain line into the seawater intake line etc, etc, etc The amount of fresh water used to flush a head properly (unless your tank is in the same cabin) would use way too much fresh water for an extended voyage. The small amount of water used to wash my hands would never flush the head. Why would I want to use my drinking water to flush the head when I'm floating in a trillion cubic miles of salt water? 
- Plumb your macerator pump into one exit line coming out of the plastic tank and just before the intake side of the pump - install your diverter valve running to the deck pump-out. If the exit line to the pump-out is sealed (and it always is unless it is being used), the pump can't pump to that point. What purpose would a diverter valve serve here?<O></O>
<O></O>

Thanks for your thoughts but I reckon the work that it would take to change my systems to your system (again, stated above, I have two heads, tanks, etc) would be prohibitively expensive and while the result may be possibly better, it won't be that much better.

Andre<O></O>


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## robfinora (Apr 25, 2001)

Andre - I did read your entire post. You come here seeking free advice so take it for what's its worth or go to a marina and pay top-dollar - no need to get confrontational. I told you that I had to go through this exercise 2x because I too thought a collapsible bag would work and it is the wrong way to go. As you already know - you are having problems with your macerator pumps trying to suck empty the bag. See my responses below in blue.

- Your vent line is not really doing much. The vent line is actually the pump-out fitting on deck, not a breather. // OK - your illustration says "deck vent". Without a deck vent, you will significantly increase the amount of odor. I would t in a vent in this line with a shut-off valve for when your getting a pump-out from a facility.
- That said, replace your collapsible tanks with a rigid plastic tank In order to fit rigid tanks would require a redesign of my boat and I have no intention of doing that. Understood - then leave the system as is. The addition of one-way valves and a power macerator pump is not the best way to go here. Get a manual hand-operatored macerator and mount it near the exit line in the bag. When you go to empty the bag - hold the bag up so that the exit line is at its lowest point and the pump gets everything out. Do not secure the collapsible bags to the point where you can't tilt or hold them up to achieve this.
- Do away with the diverter valve coming off your bowl. Plumb directly to your tank. I stated a range of reason why I don't want to pump directly to the tank.<o></o> // OK - I would not sleep well at night knowing a rubber joker valve on the head pump is holding back the sea&#8230;..unless you have to turn this valve on/off everytime you use the head it seems like a lot of work.
- Plumb your head sink drain line into the seawater intake line etc, etc, etc The amount of fresh water used to flush a head properly (unless your tank is in the same cabin) would use way too much fresh water for an extended voyage. The small amount of water used to wash my hands would never flush the head. Why would I want to use my drinking water to flush the head when I'm floating in a trillion cubic miles of salt water? // It's not drinking water you are using&#8230;.its grey water you just used to wash your hands (did you not read my post or do you not wash your hands after you pee J) - water that will be discharged anyway. If you decide on a long voyage not to utilize this or your water supply is running low - simply open the seacock. The cost of this setup is the price of a "T" fitting on the seacock. It does not get any simpler for the benefit.
- Plumb your macerator pump into one exit line coming out of the plastic tank and just before the intake side of the pump - install your diverter valve running to the deck pump-out. If the exit line to the pump-out is sealed (and it always is unless it is being used), the pump can't pump to that point. What purpose would a diverter valve serve here? // the diverter gives you 2 choices here - 1) direct discharge via the discharge seacock and 2) discharge via the deck-fitting from a pump-out facility. The second option should be mounted before the macerator so the vacuum pump from a pump-out facility has the ability to suck the tank empty with no interference from the macerator. <o></o>
<o> </o>
Google Peggy Hall "head mistress" - she has a great book on this topic that will really help you out.<o></o>
<o> </o>
Good luck with the project - Rob<o></o>


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## robfinora (Apr 25, 2001)

hey wannabe -

The sink drain / head intake is very simple. Just get a bronze "T" fitting that will fit over the seacock for your head intake line. Then run both your sink drain line (obviously cap off the current sink drain set-up) AND the intake line for the head to both the fittings on the T. Keep this fitting closed for the most part and flush after your thru washing your hands. Then you will have fresh-soapy water flushing through the system all the time. I could not believe the reduction in odor with this simple set-up. If you on a long trip and run out of fresh water or if some reason the water in the sink is not enough to flush - simply open the seacock to allow the additional seawater in to do the job&#8230;.I have never once had to do this though.<o></o>
<o> </o>
Good luck - Rob<o></o>


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## arf145 (Jul 25, 2007)

Aha! I had it backwards--thought you were putting the "T" on the sink drain outlet and capping the toilet inlet seacock. But this means that all water from the sink drain must go into the toilet, unless the toilet inlet seacock is opened, true?

Tom


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## sailingdog (Mar 19, 2006)

Arf-

If the system is properly designed, the sink can either drain overboard, or to the head, depending on how the diverter valve under the sink is set. At least, that is how it is on my boat.


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## robfinora (Apr 25, 2001)

Tom - correct. So sink-drain water will sit in the sink and sink drain lines until you flush. Then it all gets pulled through and empties out into the holding tank.

Saildog - Yes, you can use a diverter valve as in your case. If I was installing though - I would just put a T directly on the shared seackcock....accomplishes the same and is cheaper.


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## Omatako (Sep 14, 2003)

robfinora said:


> Andre - I did read your entire post. You come here seeking free advice so take it for what's its worth or go to a marina and pay top-dollar - no need to get confrontational.


Hey Rob,

My response was hardly confrontational, I was merely pointing out that you had recommended everything that I had already said I didn't want to do.  Never mind.

Just to round off a point or two:

The grey water was only grey water once you washed your hands. Before that it was drinking water.  And I say again, the amount of water I use to wash my hands would never flush a head.

If the flow of effluent needs to go through the sea cock, I would open the sea cock. If it needs to go through the deck vent (not breather  ) then I would open the deck vent. There is no need for diverter valve in this process.

The joker valve would be placed into the line between the sea cock and the diverter valve (yellow in my sketch) and would in no way be relied upon for the safety of the vessel. And for the record, the joker valve is the little rubber one-way valve where the effluent leaves the head pump, it can't be turned on or off.

Anyway, thanks for your input (and all other contributions), this thread has run it's course for me.

Andre


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## robfinora (Apr 25, 2001)

Andre - Perhaps I misread your tone earlier, my apologies - was just having one of those mornings 

I see - the diverter valve seems like it would be above the water line so I stand corrected on the safety issue.

On my boat I just do weekend sails so running out of fresh water is never an issue for us. If your water setup / usage is different, then perhaps the sink drain setup is not the best route.

Good luck with the project!

Rob


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## mgraham49 (Jan 14, 2008)

*Installing new holding tank*

Sorry to post this response rather than a new post, but could not find the button to start a new post.

I have a Pearson 10 that has, until now, been free of poo in the forepeak. Has to end. Two questions, looking at holding tanks, but it seems to me that the cleanout should be on the top, not the bottom. Don't like the thought of having a busted hose. But if cleanout is on top, doesn't that mean it needs a tube from the top fitting to the bottom so it pulls from bottom? And is there a separate hose to the deck for cleanout, or is that the same hose as comes from the head, but with a Y in it. Finally, called West Marine, and they said I really had to install a mascerator toilet so it didn't clog. That is another $500 and more complexity for a boat that doesn't have pressure water (I like it simple). Surely they were wrong. Help? I searched threads, but didn't see anything to help.

Mike Graham


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## sailingdog (Mar 19, 2006)

Mgraham-

Read this *post* to get the most out of your time on sailnet and welcome to sailnet. To create a new post, click on the *"Forum Tools"* drop down menu located on the sub-forum title bar, once you are in the proper forum. You can't do it from the general interest top level... *you must be in a sub-forum.*

The cleanout has to be on the bottom of the tank to drain the tank properly-if it was on the top of the tank with a pickup hose, it would have to leave a inch or two of standing sewage in the tank when you pumped out the tank. This would form a solid layer of crap on the bottom of the tank in relative short order, necessitating a tank replacement-unless you were willing to dig the stuff out manually. . The hose from the head usually enters the tank at the top or fairly high up so that the head doesn't have to pump against the contents of the tank and that the tank won't siphon back into the head bowl if your joker valve fails.

If you want a toilet that won't clog easily and doesn't use electricity, the best one to install is a Lavac. They're pretty bullet-proof, but are fairly expensive. They are plumbed slightly differently than a typical marine head as they use vacuum to evacuate the bowl, not a standard dual-action piston pump. Many cruisers like them because they're very low maintenance and relatively problem free and use less water than many other designs do.


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