Fitting toilets in boats is heaps of fun. Said no-one ever! Bloody waterlines and gravity and other pesky immutable laws of nature. I have put off finishing the main bathroom for nearly 2 years having built and fitted the cabinets in 2011. I had decided a long time ago that I wanted a Lavac vacuum toilet on board, well 2 of them actually, but they are very expensive. So I bought one to start with. And then, broke it! Yep $1000 bucks in 3 heartbreaking pieces. Porcelain and concrete, when they meet at terminal velocity is usually terminal for the toilet. Actually not sure that the bowl can reach terminal velocity in just 2 feet, but it sure can be rendered useless.

I enquired about a replacement bowl, after all, the pumps, seat lid and seals and other fittings are all still to be used in anger. Sure, replacement porcelain is readily available and only half the price of buying it all again. Unfortunately even that had been a stretch too far for the time being.  Then a little while ago, Whitworths were having a sale, and a brand new TMC electric macerator toilet was reduced from $299 to $229. Bargain (even at full price a TMC is a quarter the price of a Lavac). Granted I didnt really want a macerator toilet but there are more of these on boats than any other type of  toilet in various brands so they have proven to be a reasonable piece of kit. The macerator blades often clog meaning a nasty dismantle and cleaning job, but other than that, they do what they are designed to do. Lavac’s claim to fame is that the vacuum process does away with the need for maceration and are much harder to block thereby reducing the possibility of being up to my elbows in it. So due to the fact I no longer had a functioning toilet, couldnt afford to replace the Lavac right away and would need at least one functioning toilet to launch, I bought one, or more accurately my lovely wife Jo bought one for me.

I had a hunch and wanted to clear it up one way or tother,  and either way I would end up with one working toilet again.

I had a sneaking suspicion that the bowl on a brand new all inclusive $229 TMC looked remarkably similar to a now in desperate need of replacement, broken, or more precisely a pre breakage fully functioning and unscathed Lavac that delivers for more than double  the price. (quadruple if you include all the bits that do the actual work albeit in a different way, the bowl is just the start point but lets compare apples to apples, and say double when comparing the 2 bowls). And what do you know. Not only similar but, now what is the correct terminology here…..IDENTICAL!!! Not close, not nearly but bloody exactly in every way. So it begs the question on how much IP is really worth. Lavac didnt invent the concept of a vacuum, nor are they the only company in the world using seals on various items. The TMC has all the same parts as a Lavac, except their pump has a macerator, the Lavac does not, and Lavacs toilet seat and lid have rubber seals the TMC does not, about equal in cost of manufacture. Yet one company can sell their toilet for a quarter of the other? To be fair the Lavac also comes with a hand diaphragm pump made by another company, that is readily available for less than $100, the TMC does not, but I already took that into account as the Lavac retails for well over $1000. Something stinks in the Lavac pricing. Something had better not stink in the Lavac bowl.

So I unbolted all the bits attached to the bowl and replaced them with all the bits that came attached to the now fragmentary Lavac and voilà a reconstructed and like new Lavac. And some bits left over that are handy spares for a TMC but not much good for a reconstructed new age Lavac. Solution, buy another TMC. And later, all the spare bits that that go into making a Lavac what it is. The different pump without maceration which is actually a Jabsco, no really it comes with a Jabsco labelled pump, (I wont bother buying another of the optional hand pump which sells as a manual bilge pump that can be bought just about anywhere they sell boat bits) so really the only parts you need to actually buy from Lavac to make a Lavac are the toilet seat and lid and the seals that come in them. I didnt intend this blog about bog to be a whinge about stinge, but there you go. So in other words if you bought the important Lavac parts separately (the lids and seals) they are about $120 delivered, then bought a Jabsco waste pump (model 50890), about $300 if self imported from the US, over $400 if you buy one from an Aussie retailer, a hand bilge pump at less than $100 and a TMC toilet for $229 you have your $1050 Lavac and a spare macerator pump and toilet lid and seat but you will have saved about $300, just sayin.

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What I will actually be doing, is fitting the TMC in its entirety to the ensuite bathroom, and keeping the full set of spares taken off the one I bought for the Lavac replacement as the spares for the TMC, and buying a full set of spares as mentioned, enough to convert the TMC bowl if I want and see for myself which of the 2 work better. I suspect the Lavac but if I am wrong I will have the parts to convert either to become either or spares for maintenance and repair for either. Its a good idea for any cruising boat to carry spares of anything that will one day need them. And if you dont, you are almost guaranteed to need them sooner than you had planned.

So back to actual boat building stuff…..Jo had a request early on that I dont get one of those ugly boat toilets, she wants one with a full porcelain base, not those industrial looking bolts everywhere ones. No can do, dont have the room. But I like her to have what she wants, she indulges me in the entire build madness, the least I can do is get her a toilet that at least resembles what she wants. In the ensuite the entire toilet is hidden under a cover with only the top of the porcelain and the 2 plastic lids visible. So it didnt much matter what the rest looks like, even if I got one of those more expensive fully shaped porcelains you wouldn’t see it. But in the main bathroom, the toilet is more than half exposed. So I came up with a way to disguise the toilet so that it at least resembles one of those fancy full porcelain jobbies.


Way back in mid 2011 I built the curved bathroom cabinet and the matching curved toilet cabinet that houses all of the plumbing. I built a pedestal for the toilet to be mounted on so that it becomes the same height as a house toilet (I built a similar pedestal for the ensuite toilet too). The curved cabinet also houses half the toilet, leaving half exposed. And part of the thinking with the curve was to maintain a 500mm walkway between the bathroom door and the shower door, still get a full depth vanity cabinet for half the length of the room. And perhaps most importantly, the toilet did not protrude into the walkway far enough that it would be difficult to pass or use the rest of the bathroom without the toilet being intrusive, provided I mounted it on an angle. And because the bowl of these toilets is round, there is no front or side, so it can be sat on in any direction. The plumbing of either type of toilet (Lavac or TMC/Jabsco macerator type) is directly behind the bowl, that is, directly behind what would appear to be the back of the bowl by the direction the lids lift. But being round, if the lids open to the side, you can still sit on it as if the side were the back. The lids dont effect the direction you sit and dont get in the way to the side. See the construction here: and you will see the rather sad looking busted Lavac bowl.

The sideways toilet allows for the most compact installation. That only left the disguising the toilet to look like a full body model. I think I have accomplished it, or at least I will have when I spray paint the cowling I have made to simulate the look of the kind of toilet that Jo likes. I cut up part of a pipe I have been using for curved furniture corners and then just had standing in one of the hulls to explain to people where the mast posts will be, and made the front to go from the underside of the bowl to the floor. Ok, not even close, but really, who looks at these things? I think it is neat enough.

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I had initially intended that the 2 pumps (one manual, one electric) required for the Lavac would be housed in the fat part of the curved furniture. But it has been so long since I fitted the pumps for the ensuite that I had forgotten which pump was attached first, that is, closest to the bowl, the electric or the manual pump. In one case you have the electric pump pushing waste through the manual pump with the manual pump pulling the waste through the electric one, or if you mount the manual pump first then it pushes waste through the electric and the electric pulls it through the manual. I think both ways would work, but the instructions call for the electric to be fitted first and then the manual. But with a catch that I missed first time around. I noted that the pumps had to be installed in the correct flow direction, and that flow could not be horizontal, it had to be vertical or at most 45 degrees. I did that. It was a pain in the part that the bowl accommodates.

But I missed one little piece of what seems to be important installation instruction. The pumps had to be no lower than the top lip of the bowl. Bugger. That rules out getting them both in that space, and is also one of the reasons I will fit the TMC to the ensuite because I did not fulfil that part when I set it all out. I dont understand why it matters, gravity or something I dont know, and the TMC’s pump is mounted under the bowl, so I dont know why a vacuum toilet that sucks the waste out ought be any different to a macerator toilet that pulls the waste out and mashes it up on its way ought be any different. Maybe the macerator has a one way valve that the vacuum does not. I will investigate alternative places for the pumps in the ensuite, the electric is no problem, the switch dont care where the pump is, but the manual has a pump handle that has to protrude somewhere that can be pumped, and preferably in the same room and that could prove to be a problem. If I cant find a solution to the manual pump location and decide at some future point I prefer the Lavac it will just have to be an elec only toilet in the ensuite. Which the TMC is anyway. So no loss really. I like the redundancy of the manual pump option should power ever be out, but we will already have that with the main toilet anyway.

But in order for at least one of the toilets to be manual also, I had to figure out where else I could fit the manual pump in the main bathroom using the instructed rule of keeping the pumps above bowl height. I considered building another box up the walls in the corner behind where the lids open to. But that would be somewhat ad hoc and ugly. In the stairwell there is a cabinet with an opening lid on it. In the opposite hull the lid is glued down because the cabinet is so small that it is next to useless for storage and behind the dagger case over there is my wine rack. But running through the port stairwell cabinet is the plumbing for the grey holding tank that is behind the port dagger case. I may need to get to the plumbing one day so I made the lid removable even though the tank is not removable (I also put a stop cock on the out pipe so that if I am in a no discharge area I can hold that waste although that stop valve could have been mounted elsewhere if I decided I did not need access to the plumbing and glued that top down). There is just enough room in there for the manual pump and the handle of it can go through the bathroom wall back into the bathroom and it is high enough that there is room in the bathroom toilet cabinet to mount the electric pump just high enough that it is level with the top of the bowl. That should satisfy the instructions requirements.

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Also, I wanted at least one of the toilets to be able to be sea water flushable. The problem with a toilet mounted on or below waterline and taking water from outside the boat is that there needs to be a vented loop in the water inlet line with the vent mounted higher than the pitch or bury of the hull at any time to prevent syphoning of water from outside and swamping the boat (you cant sink a positively buoyant boat but you can fill a hull with water). Once a syphon starts because the water is exiting below waterline inside the boat, nothing other than closing that hole again will stop that water entering until the water level on each side is even. Sloshing through knee deep water is fun but not inside a cat. So by deciding to utilise the cabinet next door I can run my vented loop into that space, the top is about 500mm above water line, which is easily enough to satisfy that need. I have provided a salt water intake pipe but intend to run it through a 2 way Y valve with fresh water coming into the other side of the 2 way valve from our on board water (I briefly considered diverting the grey water through the toilet but decided its too complicated) and to use fresh water on the toilet and only ever switch to sea water if we are running desperately low on fresh water. The reason we want fresh water toilets is that salt water toilets stink. Or at least they do if they are not flushed every day. The smell is because there is far more microscopic life in sea water than fresh, often none in fresh because of fluoridation but a glass of seawater will have thousands if not millions of micro organisms in it. When you flush a toilet with sea water, you are actually flushing with water and micro life forms, that soon die in your bowl and decay, that is the smell you smell in some boat toilets. Some people will flush their sea water toilet with a bucket of fresh water if they intend leaving the boat idle for a day or more.

In a vacuum toilet the vented loop also acts as a vacuum release to release the toilet seats. Not sure if the toilet would release the lids if there is no vent. I think it does but it takes a few minutes rather than about 20 seconds. No big deal. Either way, with the fresh water flush option the water is under pressure so I need 2 things, firstly a pressure reduction valve and secondly, a solenoid closing valve. A vacuum toilet sucks water into it in the same motion and with the same pump simultaneously sucking the waste out and pulling water into the bowl. It does not require the water to be under pressure, in fact it has no way to stop pressurised water entering the bowl all the time, so an “on demand” system needs to be employed. I experimented with a cistern like that in a house but was convinced by a plumber friend that the motion of the boat would mean the float valve would be constantly switching on and off and would not last long in a marine environment.  But with an under pressure fresh water intake, that water must be switched on only as the pump operates and must be off the rest of the time. The solution is a 12v usually closed solenoid valve which would only open when the pump is activated on the same power loop. A vacuum pump can have a timed switch, that is you press it once and it activates the pump (and solenoid) for a set period, usually 2o seconds or you use a spring loaded toggle switch and manually hold the switch on for the duration of the flush time. I prefer the automated timed switch option. Like a normal toilet, push the button once and its done. By the time someone else needs to use the toilet hopefully the vacuum has released the lid. About the only time I think this thinking might be flawed is sea sickness. Imaging you have just returned your seafood lunch to the sea via the toilet system, you flush and faster than you can think I wish I hadnt done that up comes the cheesecake desert you had after that lovely mahi mahi and the lid still vacuum sealed in place. I guess there is always the sink in there too. Its a shallow one though!

So to be able to fit the plumbing in its new home next door I have had to cut 5 new through bulkhead pipes to allow for blackwater into and out again (the hose to the black holding tank is back in the original cavity in the bathroom toilet cabinet, so too is the salt water access point so seawater will now go next door and back via the vented loop and finally, on a positive note, it negates my need to route a power trough into the wall to house the flushing switch, it will now just go into the cabinet next door and come back into the bathroom higher up the wall to where the switch will be mounted. Cutting in these holes is not a big job, the bathroom wall is polycore and its very easy to cut new holes in. I use a large drill bit in the drill and use it like a saw. I cut oversize holes and glue pvc pipes into the hole so as to have a smooth through bulkhead transition for hoses and leads. What isnt so easy is moving pre existing holes that are now in the wrong place, but not that much more difficult. I had the waste from the grey tank in what is now the in way for the other pipes. So I had to move it over by about 20mm. Annoying for about 30 secs. I can actually still fit the various hoses in around its current position but it requires some difficult contortion and I scraped my knuckles in the process and decided if its difficult to do in the shed, it will be more difficult on the water. So move the pipe. Half an hours work now to make any maintenance a little less stressful later, it wasnt a difficult decision to make.

Once I have fitted all of the plumbing and removed it and replaced it a number of times, satisfied that it was all now relatively easy (bearing in mind that it will be multiplied in difficulty somewhat by a pitching boat and shoulder length gloves! and an old fashioned peg over the nose) I set about finishing the furniture around it all. I made lids and fairings that abut the bowl with a millimetre or 2 clearance into which I will smear a cove of white silicon sealant. Just enough to stop any water or….stuff getting under but not enough to prevent removing it all when the inevitable day comes to pull it all apart for an unblocking or a service. Here is a rather disgusting bit of information, to assist in rudimentary preventative maintenance I have decided to use clear 40mm (1 1/2 inch) hose in a couple of places so that I can monitor the flow inside. Gross, I know, but its better than the alternative. The clear hose is not as durable as the tough wire reinforced white hose that is usually used (it is only half the price though) but it will only be fitted in easy to get to places, so easy to keep a check on it and replace it when needed, whereas in the ensuite the hoses are hard to get to so I have used the white stuff for peace of mind that it will last well. The final step before finally fitting all of these pipes off with tightened hose clamps and bolts etc. is a coat of white epoxy inside every cabinet to finish the area off. What the epoxy does is provide a wipe clean surface whilst at the same time fairing out somewhat the fibreglass tapes a little because it goes on and sets so thick and glossy. Well the internals and working parts finished, the cosmetics of the room still need to be done. Wall, floor and furniture treatments. I think the walls and door will be laminated, the hull side and roof will be lined, the floor will have black and white check lino and the cabinets painted, they have been pre-faired so that final finish ought to be minimal in preparation before painting.

Thats the bog blog, feel free to comment with your poo stories should you wish.

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