Lavac holding tank layout & installation advice please

yodave

yodave

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I'm working away on the installation of a new heads compartment including heads. I've already bought a manual Lavac Popular, but obviously I also need to purchase numerous plumbing hardware. I'm looking for forum member help with:

1) the most sensible layout for a fresh water (in) tank, coupled with a waste water (out) tank, possibly along with a discharge direct to sea option (if easy/simple to incorporate).

2) the additional hardware components I'll need (hoses, valves, sellotape, kirby grips, etc).

I've created a simple diagram that shows the heads compartment which has main cabin seating to the right of the image. Also shown is the tall, thin cupboard directly to the left of the bulkhead. This cupboard is in the forecabin. Also in the forecabin is the V-berth which joins on to the tall, thin cupboard but does not dissect the cupboard.

[clicking on the image above will enlarge it]

It seems to me that the fresh water tank could be located inside the forecabin V-berth, with the hose loop inside the tall, thin cupboard, and the waste water tank under the main cabin seating. Unsure on where to site the seacock, but there seems to be two likely candidates, with one being inside the tall cupboard and the other being underneath the heads compartment floor. It may be that there's a third option located underneath the main cabin seating beside the waste tank.

Any and all advice welcome. Many thanks in advance.
 
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Hello Hugh Foulis & macd. Thanks for your replies. The reason for fresh water from a tank rather than direct from the sea is that it's supposed to hugely reduce heads pong. It also means one less hole through the hull ...which is a good thing in my books.

Thanks again!
 
yodave said:
The reason for fresh water from a tank rather than direct from the sea is that it's supposed to hugely reduce heads pong. It also means one less hole through the hull ...which is a good thing in my books.
Click to expand...

But it's a hugely complicated solution, fraught with potential for problems. Smell from water in the inlet pipe only affects the first flush after the boat's been left for a while, and is in any case minimal with a Lavac because of the nature of the installation.
 
pvb said:
But it's a hugely complicated solution, fraught with potential for problems. Smell from water in the inlet pipe only affects the first flush after the boat's been left for a while, and is in any case minimal with a Lavac because of the nature of the installation.
Click to expand...

+1
And why does it mean one less hole in the hull: how's the water going to get in there?

Can I also suggest to the OP that a simple schematic diagram would give us (well, me, anyway) a better idea of what's proposed than that strange jpg?
 
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yodave said:
Hello Hugh Foulis & macd. Thanks for your replies. The reason for fresh water from a tank rather than direct from the sea is that it's supposed to hugely reduce heads pong. It also means one less hole through the hull ...which is a good thing in my books.

Thanks again!
Click to expand...

Heads only pong for a few minutes when flushed after several days of no use. This is bacteria that grows in the in pipe in the seawater. It is a trivial matter and goes away almost at once. I would not install a freshwater tank just to stop this as space on a boat is limited enough already. Also it means carrying significantly more water. I really cannot understand why you would go this route.

As for smell elsewhere - cheap pipe will start smelling earlier that the best (vetus - also the most pliable) But I have found that wiping the pipe down with bleach or loo cleaner will get rid of the smell for at least 2 months. Keeping a heads non smelly is about cleanliness.

I would go for a system that you can either discharge to the sea or tank. Keep you dirty water runs as short as possible as you will need to pump sufficient times to get rid of all urine from the pipe - as it causes calcification in the pipe. For tanks and all the bits and advice - go to Tek Tanks near Alton in Hampshire.
 
A gravity holding tank is considerably less complicated than a pumped one. This means it must be sited above sea level so that it empties, perhaps dictating its location in the boat. Reduce hose lengths as much as possible and have absolutely no low loops where sewage can gather. I agree about the fresh water, totally unnecessary. Our toilet and graavity holding tank never smells and is used for half the year. My tank is immediately above the seacock, hose length between the two about 8 inches.
 
The original proposal is far too complicated. I have installed exactly the same set up and have Blakes inlet and outlet valves and a gravity holding tank in the outlet pipe run. The outlet goes from the lavac, through the pump into the top of the tank. There is an outlet at the bottom of the tank to the outlet seacock. The tank has an inspection hatch over the outlet so that any blockages can be cleared easily and a dip tube for a pump out. The vent for the tank means there is no need for a vented loop in the outlet.

The only challenge is finding space on the bulkhead for the tank. Mine was custom made by Tek Tanks and is 35l, but the Vetus WW type bulkhead tanks would be a good choice if you have the space.
 
I have had a Lavac for 24 years and I added a holding tank this January. The Lavac is the perfect loo for a holding system but of course I already had seacocks in place before using Simpson-Lawrence seacocks (a Blakes style) which are still in perfect condition in 51 years. Yes, obviously a wooden boat. I would recommend proper seacocks rather than ball valves.

I had a Tek Tank tank bespoke made. Well worth it and good quality. I considered a gravity system which is a good idea but I discounted the idea because the position would have been poor. It would have worked - for a while but because the 'drop' from the bottom of the tank is almost nil and the lateral distance between bottom of tank to the sea cock isn't going to give a nice run - indeed with the radius of a good quality santitory hose it might not have let a direct drop from the tank - poor engineering obviously if I had done that choice. Yes I could have raise the tank but that isn't good sense, I wanted to get the weight of a full tank as low as possible.

The Lavac system is perfect with the one pump (and you could add an electric pump). Two diverter valves give the perfect solution - one between bowl and pump which give the choice of bowl or tank (to empty) - and the second between the pump and the seacock so it can choice to exit the loo or the holding tank. Err, 140 strokes when the tank is full!

I chose not to have a flush out facility. No 1, I didn't want a hole in the deck - a lot of structure troubling the location, No 2 the wash-out pipe into the tank would have intruded the fore cabin and the port fore bunk in particular, No 3, the Lavac can flush/wash out quite easily. The wash out from a hose on deck just puts some water into the tank and doesn't much stirring - so its not better than flushing through the Lavac. If you have used the wash out, you need the pump out station and they are still not that very frequent. So you can't use alongside unless there is one. In the Lavac, I flush seawater half a tank and then go to sea. Pick a vigorous wind over tide - first on the beam and then ahead pitching. Nice stirring and so empty the tank. Perfect. So no wash out system as a separate part is necessary.

As a wooden boat and a spoon bow, the space for a holding tank and getting the pipes is quite a challenge but it was possible. How much do you flush with the contents into the tank? Umm, we tried just 6 pumps which vacants the bowl properly but it drips at the end of the process a little. Crew don't really like the drips at night so pump minimum times 10 times and the drip does not continue.

Get the vent for the tank as wide as possible which means that there is no smell. The Lavac needs a vent in the inlet pipe as part of its system and that works fine. The two vents prevents no syphon.

I have my holding tank plan by Tek Tank somewhere and I can email it if you want - PM me. I am trying to upload the images now. Only managed to upload this one so far but others will add:



The holding tank under the port fore bunk 75 litres and will 'hold' 4 adults at least for 4 days usual usage:

[URL=http://s217.photobucket.com/user/rgaspar_album/media/P1010250%20-%20Copy.jpg.html]

Heads compartment:

[URL=http://s217.photobucket.com/user/rgaspar_album/media/P1010258.jpg.html]

Explained:

[URL=http://s217.photobucket.com/user/rgaspar_album/media/Holding%20Tank%20Drawing%201.jpg.html]

Where's the vent:

[URL=http://s217.photobucket.com/user/rgaspar_album/media/Day%201%20getting%20better%20clean%201.jpg.html]
 
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Very nice arrangement. I wish I had such easy access, mine is a bit of a nightmare. My 50 litre holding tank is immediately behind the toilet in a rather similar heads space to yours. I moved the toilet inboard a few inches and Tek-tanks made me a tank to fit.

My only other comment - it is very rare that we, or I guess most people, sail with a full tank. Ours is emptied at the first opportunity, so the weight of the contents higher up is not all that significant. It's only 50 kg anyway, less than I weigh by some margin, hardly an issue for a short time on a 7 ton boat.
 
I agree. I empty at the first opportunity but I have the tank a little further forward I guess so I had got perfect balance fore and aft before the holding tank so I wanted to get it as low as possible - which was necessary anyway to get it under the bunk.

OP - avoid fresh water - imagine how much water you would need and weight up forward. And the sea water doesn't cause the problem.
 
Great information. Thanks to all who have given me advice :)

pvb

The fresh water tank solution was recommended by a chap at our club, but I have no first hand experience of this. Reading through the replies, I can't see any forum members who think that fresh water in is a good idea, so I'm definitely going to reconsider this. Thank you.

macd

Thanks for your reply. One less hole because our yacht already has a redundant water in deck fitting along with pump out fitting right above the tall thin cupboard on my diagram. That said, I'm drifting towards sea water in now.

Chris_Robb

Thanks for your advice. I'll check out Vetus pipes. It's really useful to have a steer on the additional components I'll need; which components are good and which to avoid. Thanks also for the pointer on Tek Tanks. Reading through the other replies, it seems that Tek Tanks are well thought of amongst forum members.

vyv_cox

Although I wasn't aware of this solution, now that you've mentioned it, I can see the sense in a gravity holding tank. The only way I could see that fitting is to have it situated in the tall thin cupboard in the fore cabin where I had envisage the pipe loop, however I guess I could also explore using the space occupied by the small cupboard inside the heads compartment. That's not visible in my diagram, but it's essentially just above the photographic section. Thanks also to you (and Chris_Robb) for advice on keeping the hose lengths as short as possible. That's something I'll keep in mind when deciding where to put things. Thanks for your help.

Tranona

Thank you for your input. I'll need to do some research on the gravity tank option to see if I can make that work. Tek Tanks and Vetus are now firmly on my shortlist.

Tiller Girl

Having the weight of the tank lower is a consideration, however vyv_cox probably has a point about the tank being empty most of the time. I think like you, I'll need to be convinced that the gravity system will work well within the confines of the available space that I have on board. Thank you very much for the detailed narrative, photographs, and diagram. They're particularly useful and will help my understanding of the mechanics, processes, and components that I'm going to have to get my head round in January. I'll be coming back to your photos and diagram as my installation progresses. Many thanks.

TC Tuckton

+1. Thanks for your comment.

To everyone who took the time to reply; that's been incredibly useful advice and input which has given me lots of food for thought.

Thanks again and Merry Christmas!
 
yodave said:
Great information. Thanks to all who have given me advice :)

pvb

The fresh water tank solution was recommended by a chap at our club, but I have no first hand experience of this. Reading through the replies, I can't see any forum members who think that fresh water in is a good idea, so I'm definitely going to reconsider this. Thank you.

I claim a Lakesailor
Click to expand...
 
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