Requesting Help from Headmistress

peteandthira

peteandthira

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Hi HM

I see many of your very knowledgeable posts concerning toilets, some of which mention white vinegar and water. I have a holding tank which I tend to keep half full of clean fresh water for most of the time, so that it is free to slosh round and clean itself. How much vinegar should I put in, and for how long should I leave it in? Should I flush neat vinegar down the loo or pour it into the water already in the tank?

Much appreciate your help on this one. No problems as yet after one year, but don't want any either!

Pops
 
...not HM, but have been following her advice for a couple of years. We put about half a litre of white vinegar down the bog at the end of every weekend and pump so as to try to leave it in the pipe. Has worked brilliantly for us, and even made GL "pong free" after being sat with seacocks open for 2 years.
 
Not HM either... but... as far as I'm aware the white vinegar treatment is to clear calcification in the pump/pipes. I wouldn't have thought that it would be very beneficial in the holding tank. It won't do any harm, I'm sure... but not a great benefit either.
For the holding tank I would have thought that the 'blue' chemical toilet stuff would be the best.
Just my opinion of course... I bow to Peggy's infinite wisdom on this. You could have a look at the Tek-tanks site, (http://www.tek-tanks.com) it might have the answer to your question. Or do a search on here
Cheers.
 
Jeez, where do you buy so much vinegar? Are you towing a vinegar bowser!!

Thanks, I will get SWMBO on the case on her next Tesco run!

Pops
 
Not HM either but can you help. Following HM's advice last winter I am going to fit a holding tank this winter but find that if I get a ready made one, because of shape and dimensions, the size might be quite restricted. The alternative is a purpose made one shaped to fit all the space available but they are pretty dear. What volume does one shift per go? I know this will depend on circumstances but does anybody have an 'average'?
 
IMHO you should get one as big as you can. I can't remember the capacity of ours, but it lasts about a week if you pee over the side. After the other thing, you need plenty of flush water to keep your pipes clean, so small is not good. Additionally, ours has a macerator outlet with seacock. If that seacock is left open, then flush water can slowly drain out through macerator under gravity, leaving an increasing proportion of no 2's in the tank. This will eventually block your system and stop the macerator.

Solutionn to that, fortunately, was to reverse the terminals on the macerator and run it backwards. Might not always work though.

Any advance on that, HM, wherever you are?

Pops
 
This brings to fore the question how does one estimate holding tank size

Domestic electrical apparatus consumption is based on diversity factors . Are there there similar factors for ships loos eg

Pees per day per person multiplied by the number of crew times say 0.8
plus Equivalent formula for the other matter


Volume of Pee per person calculated on average bladder size etc

Estimated time within 3 miles from shore say 1 week


In my opinion leads to a pretty big tank so you have to add fuel costs for the many trips out to sea if you want to keep a small tank

One idea is to tow an inflatable bag behind you in the dinghy into which you can pump out your holding tank somewhat similar to the fuel bags the army used or used to use . I think they were called Draycons or something similar. Dinghy would act as emergency bund if tank leaked thus saving you large fine from Authorities
 
I have a retro fitted holding tank, the capacity of which I know not. HOWEVER.... as a guess I'd say in the region of 50 lts. How long this it takes to fill this is a subject over which I have pondered...but not for long. Strangely there are other things in life which demand my more urgent attention.
Suffice to say... that if using a holding tank with limited capacity I'd think one would be frugal in the flushing department.
Without wishing to promote lurid mental images, I would suggest that the size will be determined more by the available space and a that a suck it and see approach is best.
 
There is guidance on the USCG site on roughly how much volume is required, but still depends on how many people onboard, how many days, and very much on what type of toilet and how you use it. I corresponded with The Headmistress on this subject some time ago , and dont believe you can get better advice that what she sent me:

<span style="color:blue">There really aren’t any hard and fast answers to the question of size. There have been numerous and sometimes arcane attempts to arrive at one, but what it really comes down to 99% of the time is: how much space there is in the boat to put one--or (more often than not) more than one if the boat has two or more heads. The hose run from either head to the tank shouldn't be longer than 6-8'...10’ is the absolutely maximum. Any longer, and you'll always have waste sitting in the hose to permeate it. So, if the location you’ve picked means it has to be longer, find another location for the tank that's closer to the head. If you have two or more heads, you may need two tanks...or--unless you're in "no discharge" waters--a Type I or II MSD on the head you use the most and a tank on the other one.

Here's MY rule of thumb--and it's based on the size of the boat:

under 30': 12-20 gallons.

30-35': 20-30 gallons.

35-40': at least 30 gallons...

40' plus: at least 40 gallons total, more if you have room.

There are just too many variables to do it any other way, different types of toilets use different amounts of flush water and people are different, but the following information may help you decide. Just remember that no one has EVER complained that his holding tank was too big!

Vacuum toilets and electric macerating toilets that draw off the onboard pressurized freshwater system use the least flush water--1-3 quarts/flush.

Manual toilets use about a gallon/flush if pumped long enough to completely rinse the sewage out of the head discharge line. There are ways to cut down on that--rinse out the line once a day instead of pumping enough water through with every single flush, but the average will still be at least half a gallon, whether the toilet has a piston/cylinder pump or a diaphragm pump.

Electric macerating toilets that have integral raw water intake pumps need 1-3 gallons per flush, because there's no way to switch to "dry bowl" without frying the impeller in the intake pump. A couple of brands/models have separate pumps using separate motors, which cuts the water consumption considerably, but you still have to run enough water through it to clear everything out of the macerator and pump unless you want to deal with clogs.

The further the tank is from the head, the longer ANY toilet has to be flushed to move the bowl contents from the head to the tank.

Those are the parameters for the toilets. Now we need to factor in people: Women go to the bathroom more often than men (women also tend to use about 5x the toilet paper that men do, but that's another issue). Children tend to fall somewhere in between women and men. The average urine "deposit" from an adult is about a cupful (6-8 oz)...somewhat less for children, depending on their ages because their bladders are like the rest of their bodies--they grow as the child grows. Some people drink more liquids than others...some sweat more of it out than they process through their kidneys...and that can vary with the time of year.

Keep track of how many times you have to use the toilet each day...multiply that by the average volume...then by the amount of flush water your toilet needs, add at least one flush/person/day for solids too (double the flush water volume for that) and you'll come out with the same answer I always do: it's totally impossible to find enough space--at least space you're willing to sacrifice for tankage--for a tank on your boat that will last 4 people a week without a pumpout--and it's unlikely that even two people won't fill it in 4-5 days--unless the lee rail gets a LOT more use than the toilet.

So we're back to my "rule of thumb"...or smaller if there isn't even that much room.

Peggie
</span>
 
I can't imagine what benefit vinegar has in a holding tank...it won't hurt anything, but its only purpose is to prevent sea water mineral buildup in the head discharge line. A cupful--two at most--flushed through the line once a week is certainly enough to do that...any more is just wasted. (Same is true of oil poured into the bowl to lube the pump, btw...a tablespoon does as much good as a quart...the rest is just flushed out.) Leaving your tank half full of water doesn't accomplish anything either...just gives the bacteria in the tank a larger medium in which to grow.

Tillergirl: As for what size tank and average volume/flush: the average flush volume, including waste is about 2 liters...the average adult uses the toilet 5/day. So two people continuously aboard will put an average of 10 liters/day into a tank. You'll have to do your own math from there to determine the optimal size tank for your boat and crew. That'll prob'ly result in a size that's bigger than your entire boat...which puts it back to what Talbot quoted from my book: find a location within 6' of the toilet and fit the biggest tank you can into it.

However, you Brits have it a bit easier than we do...a LOT more waters in which the toilet can be flushed directly overboard than those in which holding is required..so you can prob'ly get by with a tank that's half the size you'd need here. I realize that's about to change, though...and since no one has ever complained that their holding tank is too small, go with as big as you can find room for...'cuz if you don't need that much capacity now, a future owner will.

Pops, reversing the macerator is NOT the solution to eliminating sludge in the tank. All tanks need to be thoroughly flushed out 2-3x a year. This is done by putting 4-8" of water into the tank via the deck pumpout fitting--'cuz that sends the water into the tank at the bottom to stir up the sludge and put into suspension so it can be flushed out. Do it 2-3x to make sure all the sludge is gone. Or, if you have a deck wash, put it into the deck pumpout fitting...let water run till there's about 4-8" in the tank, then continue to let water run while you turn on the macerator and let it run for several minutes.

It's especially important to do this--and to make sure the macerator is thoroughly rinsed out--in preparation for winter layup. Otherwise, the sludge can turn to "concrete"--which nothing will dissolve that won't also damage the tank--and the macerator impeller will become tightly stuck to the inside of its housing, most likely causing a vane to break off the first time you try to use it in the spring.

It's also wise to keep the thru-hull closed while underway, and especially while away from the boat.
 
Peggy

Thanks for the info. I didn't reverse the macerator to do away with sludge, it was to free it up after jamming solid. It worked, and subsequently emptied the tank normally.

Pops
 
Thanks for all the comment. Talbot, your 'quote' amused me in the sense that it appears the bigger the boat you've got, the more often you go to the loo! Yeap I know that's not what was meant but it amused me. To hit that scale I shall have to have an expensive bespoke one made. Headmistress, thanks again. I have a nice adjacent spot under the front bunk - yeap the sounds are going to be less than choice - but having a spoon bow, the taper closes in towards the bow and rules out any decent sized vetus ready made choice. The annoying part is only by 1".

It has just occurred to me that having a Lavac, I know that it takes 12 pumps to clear and flush, so all I need to know is how much a Henderson Mk V pump shifts per stroke and I have some data for accurate calculations on 'how many goes per gallon'.

Thank you again.
 
Just checked on the Whale website and the Mk V shifts 0.93 litres per stroke, so we shift say 12 litres minimum per flush - haven't tried less. If I fitted a 61 litre Vetus tank, that gives us 5 goes! All of which tells me, that I probably don't need to pump 12 times (I think thats what Lavac recommend - I suppose they err on the side of caution to allow for those with a little distance from bowl to seacock). But on that basis then I need the expensive bespoke tank! Anybody spot a flaw in the sums?
 
Don't go with a bladder for waste holding. Because they're designed to hug the contents, eliminating air space above the surface, it's almost impossible to prevent horrible odor out the vent each time the toilet is flushed. Get a good quality rigid plastic tank from Tek Tanks. I'll be glad to help you spec out the ssytem via email. Meanwhile, please read the "Sanitation Guide" on their website to get a good starting point.
 
Peggy

I know that! This was before we realised that the "liquid" was draining away all the time, thereby "concentrating" the solids in the tank between drainings. It always amazed us how long it lasted between emptyings!

We are more careful now, and close off the exit when it is being used. We then thoroughly flush it out after each use, including with fresh water as a final rinse, leaving it really clean. We tend only to use it at all if on board for extended periods, using the sea toilet option or marina bogs where possible.

However, thanks for your continued interest. I will be reading your book soon so I presume I will become an expert! (Ex meaning "has-been", Spurt being a "drip under pressure")
 
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