Simplest waterakers?

[Mariner777]

Have decided it would be wise to have some sort of water making device aboard. Have seen the aquamate solar still inflateable and katadyn powersurvivor 35 hand pump. Ebay has a bunch of military hand pump types that need a new membrane for under a grand. Is the inflateable solar still garbage? Would a 15 year old NOS gov surplus hand pump unit with a new membrane be effective? I would also consider a simple 12V system but I dont want to permanently plumb in one this is more for if I were to run out of drinking water due to say doldrums then I need water for showering etc. More a contingency device any experience with the above units or suggestions on super simple inexpensive units?

[VetMike]

The easiest and least costly is the solar still. They work but take a long time to produce any appreciable amount of water. I was trained in their construction and use when I went through survival training in the Army. The hand held pumps like the katadyn are good but expensive and require membrane replacement often if you are using them on really brackish water. There is a straw like filter on the market which I think is made by katadyn but I have no experience with that. REI is a good source for water purifiers. Just remember that membrane size (usually measured in microns) is important. The finer the membrane (ie lower micron number) the more filtration but the harder it is the filter the water and the cost of the filter is greater. Always make sure the filter will filter out cysts and remember that filters do not purify the water.
Reverse osmosis (the typical watermaker seen on smaller boats) requires electricity and membrane changes dependent on how dirty the water is and generally work better if they are working all the time. I have looked at a home RO device that makes about ten gallons a day, operates on 110 and has relatively cheap filters. I am not sure how well it would stand up to the marine environment but for less than $300 I might just go that direction. It can be operated intermittently (we have one on our sink for drinking water) but, again, it does not purify the water. We have an aquifer that we draw from so the RO device doesn't work that hard.
Bottom line: a watermaker for emergency use is a necessity if you are going off shore, the katadyn is the best. An RO device is the best bet for the boat and you can get one that will make enough for your daily consumption. Never assume that the water coming out of the watermaker is potable unless the manufacturer states so or you sterilize it yourself.

[hellosailor]

Mariner-
"for under a grand. "
You know, if this is for contingency use only and won't be regularly used, it might be more effective to just buy and stack a couple of dozen bottles of water before a major crossing, alsong with an extra couple of jerry cans of fuel. Use 'em, sell 'em, or throw 'em away on the other side, instead of spending $1000 on something that "should" still be in working order when you need it, if you need it. Or a felxible tank, a blivet like the Nauta tanks, and just fill it before those big trips.

Solar stills work, but generally produce very little and need a flat and stable area to be set up on. Rough water, pitching boat, gray skies? No water.

[mitiempo]

I agree with hellosailor. A watermaker likes to be used and maintained, not sit unused. Membranes are expensive and they use amps. Store extra water in odd corners in Nalgene bottles or other containers.

What kind of boat and where are you headed?

[SlowButSteady]

As other have indicated, increasing your storage capacity is often a better way to go. For the price of any halfway decent RO unit you can buy a LOT of plastic bottles.

[imagine2frolic]

We have a 150 qt. cooler, and nearly filled it in a couple of hours of rain last week. It was just sitting on deck with no catchment attatched. Our bimini is a catchement that covers 50sq. ft. We are waiting on delivery for 2 more smaller catchement cloths. To attatch to the standing rigging. Adding a saltwater pump to the galley makes a huge difference too for cooking, and cleaning dishes..........i2f

[VetMike]

I would agree that taking water or using a catchment system is the absolute cheapest way to go, ignoring the cost of containers. If you follow the moct common recommendation of 64 ounces of water per day for an adult, that is about 1.8 liters. Children need about 48 ounces per day. This goes up rapidly as air temperature and activity increase. I taught my medics that the urine should remain clear and the soldier should be sweating. If the urine is not clear and/or the soldier stops sweating, has dry mucous membranes then they need more fluids. An afterthought; the human body requires a minimum of about 450 cc of water per day to just clear the BUN generated each day.

[genieskip]

Originally Posted by VetMike

An afterthought; the human body requires a minimum of about 450 cc of water per day to just clear the BUN generated each day.

What's a BUN? For us non medical types.

[Michael K]

Originally Posted by VetMike

I have looked at a home RO device that makes about ten gallons a day, operates on 110 and has relatively cheap filters. I am not sure how well it would stand up to the marine environment but for less than $300 I might just go that direction.

Several years ago I spoke with an RO specialist about this option. He explained that land-based versions for home use do not measure up to the needs of a desalinating system. The specs for saltwater desalination (finer microns and more force through the membrane to get a potable result IIRC) would not occur. In addition, those home-based units would fail quickly if used to desalinate.

[VetMike]

Genieskip, BUN is blood urea nitrogen, essentially a waste product. It is removed by the kidneys. You make a certain amount everyday and that means a certain amount of water intake is required. Sorry, should have explained that in my post.