Help needed with holding tank

[roger]

I find to my dismay that I must put a holding tank in my boat or I wont be able to visit Finland next year.
First I need information Yoohoo Headmistress - as a man said to me in the Faeroes (non boat) once "You have visky - I have money". I think you have written a book or books on the subject.
Because Badger is narrow gutted I have a problem with space. About the only position is under the toilet in a 600 mm. wide compartment. OK it has to be specially made for the hole.
Next is the question of which pipe configuration to use. large diameter pipe and 3 way valves would obviously soak up a lot more space.
What is the most straightforward system.
One of my friends has a 3 way vlve at the toilet outlet leading either to a seacock or to the holding tank then a pump then a second seacock. Is there any reason why this is unsatisfactory? At least it removes the need for a second 3 way valve.
Second possibility - route all "waste" first into a holding tank and then via a pump to a single seacock. What's to be said against this option.
In either case a deck emtying fitting and a filter cum vent would be used.
Final question. An electric emtying pum would seem to greater ease of positioning compared with a manual pump that has to be accessible. What reasons are there not to fit one?
Many thanks for all responses


<hr width=100% size=1>Roger

 

[Sea Devil]

Not sure if I can really help as I have only fitted one - for Turkey then nobody has ever asked to see it.

First off they all pong a bit - do not think its a good idea to not have the first 3 way valve to have the direct overboard system as an option...

Sunsail all appear to have gravity drop from the tank to the sea - but guess you need a sea cock at the outlet or could you put a 2nd 3 way valve on the original direct outlet tube.

The pump out motor I fitted instead of going the Sunsail route cost a fortune...

I also fitted a very expensive vetus no smell filter into the air vent tube for the tank and it seems to have been a waste of money in retrospect.

I almost never use the thing and every few years have to replace the 3 way valves cos they sieze up! Sodiummetabisulphate helps to get rid of the pong.

This is all very anecdotal and I think there are loo experts - a lady on the forum

<hr width=100% size=1>If you have time please visit my web site -
<A target="_blank" HREF=http://www.michaelbriant.com/sailing>http://www.michaelbriant.com/sailing</A>

 

[HeadMistress]

My book does indeed include several chapters on installing and maintaining a holding tank. However, Tek-tank (with my permission...though If I'd known my book would have a market in the UK, I might not have been quite so generous <g>) exerpted and published quite a bit of it on their website at http://www.tek-tanks.com/Pages/frameset.htm
and I think it will answer most of your questions about tank location, piping etc...so you might want to start there before setting any plans for size and location in stone. Tek-Tanks can custom make a tank to fit any space and do make a very good quality tank for a reasonable price. However, if you'd like to buy the book, it's on my publisher's website at http://69.20.93.241/store/customer/product.php?productid=40&cat=&page=1


Plumbing: one y-valve that allows you to choose between going directly overboard or to the tank. I would specify TWO discharge fittings in the tank...one to go directly to the deck pumpout fitting, the other directly to the overboard pump and thru-hull. You should not need a second thru-hull unless the line from the tank is much longer than about 6'. A tee or wye fitting--no y-valve--is all that's needed to connect the tank discharge line to the toilet discharge line. Pipe size should be the standard 1.5"...no need for it to be any larger.

Whether to go with a manual or electric pump to dump the tank is up to you. However, unless the tank and toilet share the same thru-hull, the thru-hull for the tank should be kept closed at all times except when actually dumping the tank--in fact, ALL thru-hulls should be kept closed except when actually in use...making a manual pump not much more inconvenient than an electric pump. The only major downside to an impeller macerator is, if it's not used regularly, the impeller can get stuck to its housing and then break when started up again...whereas a manual or electric diaphragm pump can sit for long periods and still work

"Second possibility - route all "waste" first into a holding tank and then via a pump to a single seacock. What's to be said against this option. "

Why put it in the tank it you don't have to? A blocked tank vent or a failed pump will prevent your being able to empty the tank...can prevent the toilet from being used...use the tank only when you must.

Let me know if you have other questions.

<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987

 

[Robin]

<blockquote><font size=1>Quote from previous post:</font><hr>

First off they all pong a bit

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Not all do, ours for one certainly doesn't! Ours is either pumped directly overboard via a thru-hull 'Y' valve or with the lever over is pumped into a S/S tank. The tank is then emptied either via a deck pumpout or via a second thru-hull and a manual Henderson pump. We rinse it by pumping clean seawater in. leaving it a while at sea to slop around in the tank, then pump it out, no additives, no chemicals and no smell.

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[snowleopard]

we designed in the holding tanks- 50 gal in each keel and the heads discharge direct into the tanks. the tanks can be emptied through a deck fitting or through a bilge pump to a seacock below w/l.

the discharge pump has a Y-valve on the input side so it can also suck from the bilge. the pump is large capacity and easy to strip. the only time it has blocked was sucking bits of glass fibre left from building.

the only smell is when pumping the head pushes air from the tank out through the breather.

(p.s. has anyone fitted a carbon filter afterwards and did it stop the smell?)

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[jfm]

A few additional thoughts:

1. Macerator pumps are often damaged if run dry. This is easily done for various reasons. But I notice Jabsco now sell one that can be run dry

2. Our pump has a slot in the end of the motor shaft that you can put a screwdriver in to crank the pump and clear a blockage in the macerator unit. So always mount the pump where you can reach into the bilge and get to/use the screwdriver slot

3. Carry a complete spare pump/motor unit. They do block and break. If it busts it's pretty messy disassembling and fixing it, and they're pretty cheap, so much better to dump the whole thing in the trash and fit a new unit

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[Rohorn]

Hi....I had a stainless holding tank that literally rotted...small holes appeared, Gawd awful smell etc..After advice on this forum I called Tec- Tanks (address in small ad end of PBO) got a polypropylene tank made to very exact dimensions, great success. Some comments......
There are three pipe connections, In, Out and Breather. I couldnt see why the breather should be 1.5 inch like the others, so I specified 0.5 inch. This is fine while we simply pump out well off shore, but apparently if one cruises somewhere where they actually do have a pump-out station, the rate of pump-out is so rapid one risks imploding the tank if the breather can't cope. So I have been told.
Also, the macerator pump out units supplied by Johnson Pump or Jabsco should for preference be mounted below the tank according to installation blurb, to ensure easy priming.
BUT....I recounted my experience some months ago when cherry stones, emmenating from a passenger who had swallowed a large quantity of cherries whole without spitting out the stones, blocked the pump with the holding tank full. That burned into my conciousness that it is imperative either to have a shut off valve between the tank and the pump when you have to have the pump apart to unblock it, OR have the possibility to lift the pump and the connecting pipe up above the level of the stuff in the tank when you open the pump.
Believe me , this will happen some time, and it is no joke (except to everyone you tell about it). Even Headmistress had difficulty keeping a serious demeanour. It happened twice, once with a Jabsco, then with the Johnson replacement. Some cherry stones float. Some don't. I had to suck the tank out with a wet 'n dry vac , so do leave room to get one of those onto your tank outlet pipe.
Headmistress also quoted a similar tale of the infuriated skipper who told his kids not to throw their chewing gum down the heads again. So they swallowed it instead.
Have a good stay in Finland, but perhaps include a print-out of the above in your crew briefings.
Cheers.....R


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[Birdseye]

If possible it is good to use domestic white ABS piping and solvent welds. The thing that makes the plastic in flexible pipes flexible also makes it microscopically porous and eventually smelly, but a system using abs pipe doesnt smell. Even after 5 years - or at least mine didnt. You can connect abs to the pipe outlets on the toilet by butting the ends together and using a nvery short length of flexible just to cover the joint.

I connected the system so that everything flowed through the holding tank and avoided valves altogether. The outlet from the tank was a pipe going through the top of the tank down to within an inch of the bottom. I found that a Henderson diaphragm pump could then be use to start up a syphon and the tank emptied itself with no further pumping. This also made it easier at end of season wash out time when I put a hose into the breather, started up the syphon and with the help of a bit of mobo wash could leave the tank to flush itself.

One golden rule though was to adopt the flotilla approach - no paper, towel etc don the loo. Everything into a plastic Tesco bag in a waste bin - suproisingly it didnt pong at all

<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[wagenaar]

I had a LAVAC-toilet in my boat and a polypropylene holding-tank, which was made to order for the space it was put in. I used two three-way valves, one before the pump and one after the pump. The valve after the pump was connnected to the outlet seacock and to the tank. Depending on where I was, I pumped the toilet straight overboard or into the tank. This last normally in harbours and on anchor. The valve before the pump was connected to the toilet and to the holding-tank. This allowed to either pump out the toilet or the tank. For this to function the outlet of the tank has to be below the pump. The valves also allowed to pump the contents of the tank around!! This last if you had not positioned the valves properly, but also if you filled the tank with some water, it could be used to clean the inside of the tank.

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[Anonymous]

>>Not all do, ours for one certainly doesn't! Ours is either pumped directly overboard via a thru-hull 'Y' valve or with the lever over is pumped into a S/S tank. The tank is then emptied either via a deck pumpout or via a second thru-hull and a manual Henderson pump. We rinse it by pumping clean seawater in. leaving it a while at sea to slop around in the tank, then pump it out, no additives, no chemicals and no smell. <<

Exactly the same with us except that we have a plastic tek tank and the holding tank is below the waterline so I can fill it to rinse just by leaving the discharge seacock open. No smell at all and it is in constant use.

One thing - I would not be without a contents gauge. Mine is a very simple three stage LED type as supplied by Tek Tank which suffices.

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[HeadMistress]

"I couldnt see why the breather should be 1.5 inch like the others..."

The primary reason is to provide more oxygen to the tank...oxygen/aerobic condition prevents odor from occuring." You'll find a more detailed explanation of how that works in the Tek-Tank sanitation guide on their site. But larger vent ("breather") is also less likely to become clogged or even partially clogged too, which could indeed have dire consequences at a particularly strong pumpout...but would also prevent even the macerator from being able to empy the tank.

Btw...are you sure your tank is polypropylene, and not polyETHYLENE? Cuz I've only found one mfr (C.C.Tech in the US) that use PP for custom welded tanks...I'm 99% certain that Tek-Tanks does use PE.

"EVEN Headmistress had difficulty keeping a serious demeanour..." Good Lord, Roger, you'll have people thinking I have little or no sense of humor!

<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987

 

[jimboaw]

K.I.S.S. no problem for us. We have 2 heads, one with a holding tank which we use in harbour the other goes overboard. The former is plumbed so all waste goes to the tank and the disgharge is through hull via a manual pump or deck pump out. Never had to use the deck pumpout in the 5 years since I installed it. We always managed to get out to sea before the tank (20gall US) Never had an odour problem maybe because we flush with fresh water when possible and use a biocide

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[Keith]

small point, try and locate your through hull the opposite side of the keel to your engine cooling intake, or make sure you only pump out with the engine off!!.......keith

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[Robin]

Why didn\'t I think of that

<blockquote><font size=1>Quote from previous post:</font><hr>

the holding tank is below the waterline so I can fill it to rinse just by leaving the discharge seacock open.

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Our tank is below the waterline too, it never occurred to me to just open the outlet seacock to fill it for flushing it clean so I stand there for ages pumping the loo - daft!

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[roger]

Many thanks folks

My goodness you folks have come up trumps - and other things. I am extremely grateful for all your information and views.
There are a number of points here where views differ :-
Use of stainless or plastic polyethylene tanks - a bad experience noted with Stainless.
Different plumbing systems used. Incidentally I found that two catalogues, Vetus, and Cleghorn showed the all through the holding tank method. It is a lot simpler to pumb. I also appreciate the case against.
Size of vent pipe. I find it difficult to believe I need a 1 1/2" vent pipe just to stop the tank collapsing on pump out. I recognise the virtue of a lot of air to keep the digestion aerobic but that size of hole on both sides of the boat, as in the Tek Tank summary, worries me for a boat that is liable to heel a lot. Is there any way of using a small air pump to forcibly ventilate the holding tank?
The manual/electric pump information is most valuable. A good manual diaphragm pump looks likely to be the most reliable, cheapest and also easiest to fix. Its just that it has to be put where you can get to the handle and it will get in the way.
Thanks again and more ideas on the subject are welcome.


<hr width=100% size=1>Roger

 

[HeadMistress]

" small point, try and locate your through hull the opposite side of the keel to your engine cooling intake, or make sure you only pump out with the engine off!!."

Also head intake thru-hull should be forward of any discharge thru-hulls...to prevent recirculating the discharge.

Re metal vs plastic: rohorn's experience with his metal tank is not unique. Urine is SO corrosive that it typically eats through a weld at a seam or fitting in a metal tank--aluminum or stainless, even thick 316--in 2-5 years and will turn the tank into a collander in an average of 10 years...a few years more or less depending on how much the tank is used, but 10 years is the average. The ONLY material recommended for waste storage is thick-walled PE...it will last as long as the boat if it's not abused--pressurized to the bursting point or subjected to extremely high suction against a blocked vent.

Remember: it's always cheaper and easier to bite the bullet and spend what it takes to do it right the first time than it is to do it over.

Peggie

<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987

 

[charles_reed]

Whilst on the subject of holding tanks

I fitted what I later discovered to be a buffer tank, around the toilet bowl.

The first occasion I used it (in a particularly pretty anchorage in the maddalenas) it filled with no trouble, but when i came to pump it out in the middle of the Bonifacio channel it just overflowed. In the end I had to dismantle it and empty the contents overboard by hand. A thoroughly dangerous and disagreeable job.

I discovered the lift pipe had been broken off inside, so when i got back to the S of France i phoned the netherlands makers and gave them a piece of my mind - a replacement arrived with 48 hours - but of a totally different shape. turns out the thing i was referring to as a holding tank is a buffer tank (to the Dutch that is).

I'm glad to report it works Ok now and yes, Peggy, it is high density PET and the breather is a 25mm pipe.

PS outlet pipes - you need to change those every 10 years or so (if you use the boat much) mine was down from 50mm bore to about 12 with solid limescale.



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[HeadMistress]

Re: Whilst on the subject of holding tanks

What the heck is a"buffer" tank??? If it's some knd of intermediate tank between the toilet and "main" tank, WHY? What's to be gained by having two tanks to maintain instead of just flushing it overboard or to the tank??? Sometimes I think boat builders deliberately over-complicate sanitation systems ...that is, if they give 'em any thought at all. Last spring I had a consulting project on a 60' NZ built trawler on which all the gray and black water tank vents terminated in charcoal cannisters in the engine room--less than 5' from a propane furnace--instead of properly out the hull. I can't even begin to imagine what that builder was thinking! At least I CAN guess that perhaps your builder mistakenly thought that a small tank next to the toilet that would have only limited use would reduce the need to maintain the "main" tank. Their hearts were in the right place, but unfortunately a second tank only doubles the amount of maintenance and hassle connected with holding tanks and related plumbing. If you ever use the "main" tank, I'd remove the "buffer tank" and simplify the system.

<hr width=100% size=1>Peggie Hall
Specializing in marine sanitation since 1987

 

[jfm]

Re: Why didn\'t I think of that

Robin the macerator pump may operate as an almost watertight closure valve, so it could take a few days to fill by this method. Does on our boat

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[Anonymous]

Re: Whilst on the subject of holding tanks

>>What the heck is a"buffer" tank???<<

I have heard this term used to describe a holding tank that has no provision for emptying other than into the ocean, through-hull. Almost pointless, it seems to me, since you can't use it when staying in ports where pump-out facilities exist and the use of marine toilets discharged to the sea is forbidden.

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