DIY Holding tank installation

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Ben998

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Hello All,
Does anyone know of any good books or websites for info on a DIY holding tank installation. It should be a fairly straightforward piece of plumbing, the only scary bit is drilling through the deck for the breather vent and pump out fitting and then through the hull for the outlet for pumping out when x miles off the coast.
There is a book by Peggies Hall thats supposedly a good guide to marine sanitation, but I havent seen it. Tek-Tanks seem to do a good range of materials and fitting with some advice on their site, but if anyone else has some pointers towards any info then that would be great.
cheers,
Ben
 
Get hold of the Lee sanitation catalogue (I think that there may be some connection with Peggie)

There's also a good section on this in the West Marine catalogue. They may also have it on their website, but I havn't looked
 
We have just completed this job. Much help and a custom made tank from Lee Sanitation (expensive but fits well); good diagrams in their catalogue of the necessary plumbing. Our head is a Lavac, who also had a useful diagram on their website, which enabled us to design a system which did not need an extra pump. We also managed the installation without any extra holes in the hull. The vent exits on the transom, since it must be sited to avoid direct ingress of water.
 
Installing a holding tank is a fairly straightforward job, although likely to teach you new ways to combine profanities.

I'd advise getting the tank from Tek-Tank...they build an excellent product and also install fittings in the sizes and locations you specify, which can make plumbing considerably easier than dealing with pre-installed "standard" locations that are never where YOU need them.

A few pointers:

Tank should be within 6' of the toilet...'cuz that's as far as bowl contents will move in the amount of time 99.999% of people will spend pumping a toilet. Further away leaves waste sitting in the head discharge hose to permeate it.

Spec your inlet and vent fittings away from the hull, toward the centerline of the boat...this will prevent tank contents from running back toward the toilet and/or spilling out the vent when heeled without any need for a loop in the line. If you have enough clearance above the tank (min. 5"), put all fittings on the top, with a pickup tube inside for the pumpout/discharge.

Vent should be at least 3/4"...I prefer 1"...and should be as short, straight and horizontal as possible. It does not--SHOULD not--go the transom because that location does not allow the air exchange needed to keep the tank aerobic. A clamshell over the thru-hull will keep water out when heeled.

Thanks for the referral to my book, Nelson...the direct link to it on my publisher's site--which may be the most economical source from the UK--is in my signature below. For heaven's sake do NOT buy it from Amazon-UK...their price is ridiculous! Tek-Tanks has excerpts from it on their site that will help you understand how venting prevents odors.

And I'm always glad to help you sort out the details of any particular installation.
 
I have the peggie hall book, very good, although much of it's content is already on the web in articles written by peggy. A few thoughts:

Consider carefully where to put the vent outlet. It will inevitably smell. When someone flushes the loo and puts a litre of contents into it, a litre of smelly air comes out of the vent. I wouldn't think you want it on the deck but I guess it depends a bit how much your boat heels. Ours is a foot above waterline in the side of the hull, 1/3 way from bow, but it's a mobo.

You could avoid drilling the hull below waterline if you switch your loo. Eg fit a whole new freshwater loo (the Tecma silence is superyacht standard and highly recommended http://www.tecma.net/nautica/ger/silence/) and flush it from the boat's freshwater supply. Then use the thru hull seacock that used to supply your seawater flush, as your holding tank discharge. This costs more money in hardware (£500 for the new toilet) BUT you avoid liftout/block off/lift in charges, so mebbe it is even-stevens and you get a much nicer boat at the end of it

The slight bodge here is that your current seawater flush inlet might be 3/4" and the macerator pump outlet is likely 1" (eg ths one http://www.johnson-pump.com/JPMarine/default.htm?page=/JPMarine/Lavatory_systems/Macerator.htm) but you will be ok with a bronze reducer at the seacock and you can if necessary change it at a later date when the boat is lifted out for some other reason

Tek tanks and leesanitation all fine. Also www.aquafax.co.uk are good supplier of kit, incl the johnson pumps and tecma gear. Based Luton
 
I've been trying to get that d'd article OFF the 'net for more than two years now...I haven't revised it since 1996, making a good deal of it obsolete and even erroneous information now. Most of the site owners were very cooperative about taking it down...but one or two (notably boatbuilding.com) have ignored every request.

It's NOT inevitable that the tank will belch odor out the vent when the loo is flushed. With enough fresh air via the vent, and the proper tank treatment, odor can be prevented altogether. It's a bit harder to accomplish on a sailboat than on a powerboat because heeling limits the vent thru-hull locations...but it can be done, and IS done--quite successfully.

I'm afraid that using a former toilet flush water intake thru-hull to dump the tank won't work either--at least not unless the toilet intake size is non-standard...'cuz toilet intake is 3/4"...manual discharge pumps are 1.5"...macerators have 1" discharge. And, depending on the location of the toilet intake thru-hull, there can also be the danger that an engine water pump can pull in waste if running.
 
We made our own by lining the hull up forward below the berth with sealed ply then copious amounts of glass fibre matting and resin. A one piece top pre fibre glassed underneath with overlaps that came up the sides was then glassed in place.

A 40mm vent went through the hull just below deck level and as Pump out facilities are as rare as rocking horse dr......s, we fitted a Jabsco diaphragm pump to the original toilet outlet.

There were two inlets, one from the heads and one from the galley. Not fancying having ANY connection between fresh water and a Loo we installed a seperate plastic water tank to flush the loo with.

We NEVER experienced any odours on deck and even though we used top domestic rigid waste plumbing fittings as opposed to the heavy duty recomended type there has never been any odours inside the boat either. The installation was going perfectly well after six years.

Goldendawn did over 5000 miles with the tank and never a problem...only one replacement outlet valve required.


Phil
 
We fitted ours a couple of years ago now, the vent is onto the deck via a charcoal filter, and it doesn't smell.
The tank etc. came mostly from Tek-Tanks, one of their standard tanks fitted under a berth perfectly. It is a small one not intended for prolonged use, just to be more sociable in confined waters.
We have a simple arrangement: Intake to toilet. Outlet via Y-valve to sea or tank. Tank outlet via electric pump (due to lack of space) to sea only. vent via filter to coachroof. It still involves about 12 miles of piping and makes the heads compartment resemble a white octopus.
One point I have found out since: not all 1.5" sanitation hose is the same. I bought mine off the shelf from a big south coast chandlery and it is a right [no thanks] to get onto a seacock spigot. I am reliably informed that other makes available mail order (more expensive of course) are easier. I'd advise you to get it.
 
Re: Holding Tank Flushing

Whilst we have the attention of the experts !

My boat has a holding tank which has the option of pump out and also gravity exit via the normal toilet flush seacock. Is there any benefit in flushing the tank with fresh water every now and again to freshen things up ?? What I am suggesting is putting in fresh water via the pump out point and then letting it exit via the seacock outlet.
 
Re: Holding Tank Flushing

Not an expert except in reading up before installing the tank, but the main stress is on getting oxygen into the tank to prevent smells. It is anaerobic activity that you want to avoid, which is why a large vent is always recommended. I surmise that you will never flush out everything, so the idea is to let it decompose aerobically and thus leave no smell.
To answer your question, it would seem that apart from the actual flushing action there is little benefit in using fresh water.
 
Hello while on the subject of marine toilets ..
I am looking at fitting holding tanks into my boat, I have been told that I could fit domestic toilets instead of marine toilets. (seemed a weird idea but could not see why not except maybe more waste) currently I have three blakes toilets, two in the bow section one aft. Does anyone know if it is a big no to fit domestic toilets to the boat.

Cheers Jamie
 
Phil said, "There were two inlets, one from the heads and one from the galley. Not fancying having ANY connection between fresh water and a Loo we installed a seperate plastic water tank to flush the loo with."

Toilets that are specifically designed by the mfr to use pressurized flush water can safely be connected to the onboard fresh water system, but toilets designed to flush using sea water should NEVER be connected to the fresh water system...it cannot be done without risk to the potable water system, and all toilet mfrs include strong warnings against doing so in their installation instructions. So installing a separate flush water tank was the right way to do it. However, combining gray water and black water in the same tank is not recommended either, because e-coli and other bacteria in body waste can migrate into the galley sink plumbing and find their way into the sink. Gray and black water tanks should not even share any vents.

Dave said, "have found out since: not all 1.5" sanitation hose is the same."

No...it's not. However, the softer and more pliable the hose, the more susceptible it is to odor permeation...because the softer it is, the further apart the molecules are...the stiffer it is, the more tightly packed they are. So while it's easier to get softer hose onto fittings, you'll have to do it a lot more often.

PK asked, "Is there any benefit in flushing the tank with fresh water every now and again to freshen things up ?? What I am suggesting is putting in fresh water via the pump out point and then letting it exit via the seacock outlet."

Yes. Not necessarily to "freshen things up," but to flush out sludge that can not only turn into "concrete" that cannot be dissolved, but clog up the discharge hose.

Jamie said, "I have been told that I could fit domestic toilets instead of marine toilets."

It's done on cruise ships and mega-yachts, but not practical for most boats...for several reasons: 1) Pressurized water is needed to fill the flush water reservoir, which requires tapping into the fresh water plumbing. That part's ok because the reservoir is separate from the bowl...but the volume required--1.5 gal minimum, is 3x the average amount used by most marine toilets. 2) Gravity is the main force at work in a domestic toilet...so unless the tank is close to the toilet and below it, bowl contents won't get there. 3)Because a vented loop above the waterline at any angle of heel is required in any line connected to a below waterline thru-hull, a domestic toilet that's also at or below waterline wouldn't be able to flush overboard at all. Those are just the most obvious reasons..I could list several more. But the bottom line is, unless your boat is very large with all plumbing well above waterline, a domestic toilet won't work.

And finally...Southace, assuming that the mayonnaise container is plastic, unless it has walls that are at least 1/4" thick, I think you're gonna live to reqret converting it to a waste holding tank...'cuz it's not made to withstand the stresses that holding tanks take from repeated filling and emptying. In fact, it's not made to be used but once for anything, only ground up and made into a new container. If it's metal, urine will rust it out in two seasons at most. Bite the bullet and buy a proper holding tank.

I'm not a fan of Charles Kanter's "KISS" system anyway...and especially not of the P-trap shown in the drawing--which is just a place for sludge to accumulate (or something that shouldn't have been flushed in the first place) and block the discharge. Without any y-valve or shutoff valve in the pumpout/dumpout line, there's no way to close off the flow of a tankful of sewage to disconnect the line to clear it. And, because everything must go through the tank, that makes it impossible to use the toilet till the blockage has been cleared. IMO, there's just a limit to the degree of simplicity that's practical...the KISS system is a bit TOO simple.
 
Sounds a bad idea. Domestics rely totally on gravity to deliver the waste to the tank. A boat system pumps it there.

But there are nice domestic looking toilets, eg tecma. These are highly recommended
 
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