Peggie, the subject about says it all. I know it depends on the kind of toilet, and how much water it uses when evacuated in the proper manner. But surely there are some rules of thumb about this? So many gallons for diaphragm toilets, so many for piston pumps, and so many more for electric flush?
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T
TOM MCNAMARA
heads
depends on how much beer you drink. my boat has 3 heads , two below and a coffee can topside.
depends on how much beer you drink. my boat has 3 heads , two below and a coffee can topside.
P
Peggie Hall/Head Mistress
Weeellllll...
There really isn't any rule of thumb. 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 two if the boat has two heads at opposite ends of the boat). Here's MY rule of thumb: 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. Vacuum heads 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 it's still gonna average more than 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 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. Ok...you have 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 with 'em. 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 weewee 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--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 head. So we're back to my "rule of thumb"...or smaller if there isn't even that much room. Nobody has ever complained that his holding tank was too large...so just find the best space(s) to put one and go through the Ronco drawings till you find one that fits it. And btw...if you have more than one toilet, the hose run from the head to the tank shouldn't be longer than 6-8'...longer, and you'll always have waste sitting in the hose to permeate it. If it has to be longer, two tanks...or--unless you're in "no discharge" waters--a Lectra/San on the head you use the most and a tank on the other one.
There really isn't any rule of thumb. 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 two if the boat has two heads at opposite ends of the boat). Here's MY rule of thumb: 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. Vacuum heads 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 it's still gonna average more than 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 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. Ok...you have 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 with 'em. 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 weewee 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--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 head. So we're back to my "rule of thumb"...or smaller if there isn't even that much room. Nobody has ever complained that his holding tank was too large...so just find the best space(s) to put one and go through the Ronco drawings till you find one that fits it. And btw...if you have more than one toilet, the hose run from the head to the tank shouldn't be longer than 6-8'...longer, and you'll always have waste sitting in the hose to permeate it. If it has to be longer, two tanks...or--unless you're in "no discharge" waters--a Lectra/San on the head you use the most and a tank on the other one.
D
D. Ebert
Jabsco Head
In a letter from Jabsco the mode #29090-2000 head uses approximately one cup of water per stroke.
In a letter from Jabsco the mode #29090-2000 head uses approximately one cup of water per stroke.
P
Peggie Hall/Head Mistress
Ok...multiply 1 cup x number of strokes to move
the bowl contents from the head to the tank, and at least 4 more to rinse the hose. There are 8 oz in a cup...4 cups to a quart..4 quarts to a gallon. Unless you quit early and leave waste in the hose, you're gonna find that comes out to close to a gallon a flush including the bowl contents.
the bowl contents from the head to the tank, and at least 4 more to rinse the hose. There are 8 oz in a cup...4 cups to a quart..4 quarts to a gallon. Unless you quit early and leave waste in the hose, you're gonna find that comes out to close to a gallon a flush including the bowl contents.
W
Wil Rogers
survive the s***
...well Owning a 46' (blue water, all sinks discharge direct) with vacuflush (and therefor a 50 gallon waste) my experience is: 2 people 1 week 3 people 3 days 4 people 2 days 5 people 1-1/2 - 2 days
...well Owning a 46' (blue water, all sinks discharge direct) with vacuflush (and therefor a 50 gallon waste) my experience is: 2 people 1 week 3 people 3 days 4 people 2 days 5 people 1-1/2 - 2 days
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