1 gallon per hour water maker

[seandepagnier]

All of the homemade watermakers seem to produce 20-40 gallons of water per hour. This is nice if you have 5 or 6 people, but if you already get sufficient water from rainfall and occasionally have to carry water, this is just a very heavy expensive device which also consumes too much power.


I am interested in a water maker that produces 1/10th or less this amount. I mostly care about it being small and not weigh a lot. The power efficiency is not so important because it's easy to produce excess power with solar panels and hydro turbines.


1) What membrane? The 20 inch by 2 inch one maybe ok, but since it's designed for 10 gallons per hour not 1, I have read that if you run it at a low flow rate it will clog. Is this actually true? Could I just take one of these and cut it down so it's only a few inches long?



2) what pump? I could power it from a brushless motor directly from lithium battery so could use a few hundred watts, but typically watermakers are using 1200 watts which is too much. Ideally it could use 100 watts or so at a gallon per hour, and this would still be a lot less efficient per gallon than other homemade watermakers. Is this possible to do? Is it possible instead to use an air pump and use this to pressurize the water even though it's less efficient if a suitable water pump cannot be found?




3) about rejection ratio. rather than a continuous rejection stream, is it possible to have a lower rejection ratio, but periodically back flush (put high pressure on output) to prevent salt buildup?




4) maybe the survival water maker makes sense for me if it's electrically driven, but the issue I have is, are these possible to maintain and use for extended periods? It seems they are expensive because the membranes are special and they aren't designed to be used except for survival and then discarded after continuous use for some days.

[LLCoolDave]

This is the best diy watermaker thread I've read.

https://www.cruisersforum.com/forums...ph-225683.html

I think some of what you're looking for is a katadyn 40e. They made a million of them and can be picked up for $1500. They can even be manually operated in an emergency. One thing you might be overlooking is that watermakers can be loud. I'd rather have a 20gph and run it for a half hour than listen to a pump for 10 hours.

[BillKny]

Originally Posted by seandepagnier

1) What membrane? The 20 inch by 2 inch one maybe ok, but since it's designed for 10 gallons per hour not 1, I have read that if you run it at a low flow rate it will clog. Is this actually true?

Yes, it is true. Running a desalinator RO membrane at lower or higher product rates than it is designed for will lead to a very short life.

Originally Posted by seandepagnier

Could I just take one of these and cut it down so it's only a few inches long?

LOL, I guess you have never actuall seen a membrane... NO.

Originally Posted by seandepagnier

3) about rejection ratio. rather than a continuous rejection stream, is it possible to have a lower rejection ratio, but periodically back flush (put high pressure on output) to prevent salt buildup?

NO.

If you do standard things in standard ways, then building an RO system is not rocket science. You follow the recipe. But even with that, many people have spent a lot of money and ended up with a system that doesn't work well (or at all!) If you are going to go off roading, the issues are VERY complex and not at all obvious.

You have looked at a PowerSurvivor 40E, right? They make 1.5 gallons per hour and consume less than 50 watts. Just what you are looking for. Small light weight, low power, suitable for long term use.

[seandepagnier]

Originally Posted by BillKny

Yes, it is true. Running a desalinator RO membrane at lower or higher product rates than it is designed for will lead to a very short life.



LOL, I guess you have never actuall seen a membrane... NO.

LOL, I have never been fortunate enough to own a watermaker.

You have looked at a PowerSurvivor 40E, right? They make 1.5 gallons per hour and consume less than 50 watts. Just what you are looking for. Small light weight, low power, suitable for long term use.

I looked at this now that you suggested it.


weight is very heavy at 25lbs. One of the reasons to have a watermaker is to not need to carry heavy water, and this is more than the weight of 3 gallons. I left on 50 day passage with 5 gallons of water in the past and I didn't have a watermaker. So if the watermaker weighs as much as 3, much it's advantage is significantly reduced. I don't plan to carry more than 5-10 gallons for atlantic crossing. I have forward osmosis and solar still for survival as well.



I realize a lot of people use several gallons per day, but I use less than 1, even when in a harbor. My boat cannot carry more than 500lbs total for all gear, more otherwise it can't cruise at 10 knots anymore in 10 knots of wind, and the speed is only 8 knots with 700lbs in 10 knots. I need to bring a lot of things not normally considered "essential" because I need them to make money where I go.



I was hoping for something lighter weight but less efficient would be fine. Also, cost seems very high for spectra so I would prefer to build my own and not need to get their replacement parts which are also expensive.


Ideally, 1/10th the output 1/10th the weight and 1/10th the price of the $1000 watermaker that makes 20 gallons an hour described in the other great thread. A higher price ok, and even 10x the power of the spectra per gallon ok if it can weigh only 3 pounds or less.

[seandepagnier]

I think the survivor 35 seems a lot more interesting than the "40e" because it weighs just 7 pounds, maybe this is what I'm looking for.

[GoneDiving]

Most of the saline water is use to flush the membranes clean rather than be filtered into clean potable water. There is so much bypass saline water than additional membranes can be added in series with minimal drop in potable water per unit. 3 membranes will consume approximately the same power as one membrane and produce near 3 times the output.

If your priority is output per amp hour, go with as many membranes as your high pressure pump can supply.

If you priority is size/weight the go for the smallest high pressure pump and appropriately sized membrane that you can find

Yes. High pressure piston pumps operating at ~1500 rpm are banshee loud. Its a simple matter to spec slower rpm motors to drive higher cc/rev pumps. Big pumps at '00s of rpm are near silent. Of course the down sides are size, weight and $$$s.

Cheers

[Sailmonkey]

Originally Posted by seandepagnier

I think the survivor 35 seems a lot more interesting than the "40e" because it weighs just 7 pounds, maybe this is what I'm looking for.

The survivor 35 is a hand pump unit. The powersurvivor 35 ads the motor and gearbox and you’re back up to the weight of the 40e.

[boatman61]

Originally Posted by Sailmonkey

The survivor 35 is a hand pump unit. The powersurvivor 35 ads the motor and gearbox and you’re back up to the weight of the 40e.

Yes, this is what I got a couple of years back for emergencies but to date never used it..
Just hoping the membrane does not have a 'use by date'..

[skipmac]

Originally Posted by seandepagnier

I left on 50 day passage with 5 gallons of water in the past and I didn't have a watermaker. So if the watermaker weighs as much as 3, much it's advantage is significantly reduced. I don't plan to carry more than 5-10 gallons for atlantic crossing. I have forward osmosis and solar still for survival as well.

Perhaps I misunderstand but can you explain how you can survive, even if singlehanding, for 50 days on 5 gallons of water. The standard is about one gallon per day per person just for drinking and cooking as a bare minimum. If you were depending on rain water to make up the difference what was your plan if halfway there there was no rain? I've made passages of 2-3 weeks when I never saw a single drop.

[Disailor]

Originally Posted by seandepagnier

All of the homemade watermakers seem to produce 20-40 gallons of water per hour. This is nice if you have 5 or 6 people, but if you already get sufficient water from rainfall and occasionally have to carry water, this is just a very heavy expensive device which also consumes too much power.
I am interested in a water maker that produces 1/10th or less this amount. I mostly care about it being small and not weigh a lot. The power efficiency is not so important because it's easy to produce excess power with solar panels and hydro turbines.
1) What membrane? The 20 inch by 2 inch one maybe ok, but since it's designed for 10 gallons per hour not 1, I have read that if you run it at a low flow rate it will clog. Is this actually true? Could I just take one of these and cut it down so it's only a few inches long?
2) what pump? I could power it from a brushless motor directly from lithium battery so could use a few hundred watts, but typically watermakers are using 1200 watts which is too much. Ideally it could use 100 watts or so at a gallon per hour, and this would still be a lot less efficient per gallon than other homemade watermakers. Is this possible to do? Is it possible instead to use an air pump and use this to pressurize the water even though it's less efficient if a suitable water pump cannot be found?
3) about rejection ratio. rather than a continuous rejection stream, is it possible to have a lower rejection ratio, but periodically back flush (put high pressure on output) to prevent salt buildup?
4) maybe the survival water maker makes sense for me if it's electrically driven, but the issue I have is, are these possible to maintain and use for extended periods? It seems they are expensive because the membranes are special and they aren't designed to be used except for survival and then discarded after continuous use for some days.

1/2 to 3/4 gal/hr about $400 non electric automatic & no hand pump. Fresh or Sea water on Amazon
https://www.amazon.com/Emergency-Sur...0RYE47F1G8HS3A

[alansmith]

Disalior... by chance, did u read the reviews on this device? I read everyone. The people who gave it good reviews... not one of them made notes of actually puttin it into service. In other words... they liked how it looked. Those people who used it hated it.

[Shaneesprit]

Originally Posted by Disailor

1/2 to 3/4 gal/hr about $400 non electric automatic & no hand pump. Fresh or Sea water on Amazon
https://www.amazon.com/Emergency-Sur...0RYE47F1G8HS3A

I am going to have a serious look at this, on first view seems a great idea, but rather than emergency use, if it can cope with occasional use in non critical situations, I would only be looking to top up my tank so when on board for a week I won’t run out of water, will probably get a water specialist to give me their thoughts as I know some of the worlds best.

[alctel]

Originally Posted by seandepagnier

LOL, I have never been fortunate enough to own a watermaker.


I looked at this now that you suggested it.


weight is very heavy at 25lbs. One of the reasons to have a watermaker is to not need to carry heavy water, and this is more than the weight of 3 gallons. I left on 50 day passage with 5 gallons of water in the past and I didn't have a watermaker. So if the watermaker weighs as much as 3, much it's advantage is significantly reduced. I don't plan to carry more than 5-10 gallons for atlantic crossing. I have forward osmosis and solar still for survival as well.



I realize a lot of people use several gallons per day, but I use less than 1, even when in a harbor. My boat cannot carry more than 500lbs total for all gear, more otherwise it can't cruise at 10 knots anymore in 10 knots of wind, and the speed is only 8 knots with 700lbs in 10 knots. I need to bring a lot of things not normally considered "essential" because I need them to make money where I go.



I was hoping for something lighter weight but less efficient would be fine. Also, cost seems very high for spectra so I would prefer to build my own and not need to get their replacement parts which are also expensive.


Ideally, 1/10th the output 1/10th the weight and 1/10th the price of the $1000 watermaker that makes 20 gallons an hour described in the other great thread. A higher price ok, and even 10x the power of the spectra per gallon ok if it can weigh only 3 pounds or less.

You are going to be hard-pushed to find anything that does a gallon a day, electrically, that weighs less. Manual ones suck except in marginal survival situations, as its a LOT OF PUMPING to even get a tablespoon full.

It's not just useless weight, its because the pressure container needs to be a certain thickness, the pump needs to be solidly built - basically it's getting close to the minimum weight it can be while still being reliable. As you said it weighs around 3 gallons of water - that doesn't seem like a bad trade off.

Also, as someone else said, 5 gallons for 50 days?! What happens if it just doesn't rain for 3 days, you are completely hooped

[Captain Bill]

To use that thing as a distiller for salt water you need to be able to boil the water in the bottom container. I bet it will use a lot of propane. Of course one could use a wood fire, but where are you going to build one in the middle of the ocean?

[Shaneesprit]

Originally Posted by Captain Bill

To use that thing as a distiller for salt water you need to be able to boil the water in the bottom container. I bet it will use a lot of propane. Of course one could use a wood fire, but where are you going to build one in the middle of the ocean?

That’s not really my issue, I like to hang on the hook after sailing although regularly go on land to eat in restaurants, not always but often, if I run out of water it’s a real pain, as I won’t be in or near a marina.
I can offset the carbon by not buying large amounts of bottled water. and not installing a large battery bank to run a conventional water maker. My propane use is quite low, well it’s ridiculously low, on the account of the restaurants - I honestly eat out more often than most people eat in.