Tweet
Portable Reverse Osmosis SHTF Water Purification System
Here's a write-up on Reverse Osmosis, RO, water purification, in the context of application in a SHTF senario.
First, there are many ways to make water safe to drink, hiking type hand pumps, water purification tablets, chlorine [bleach], boiling, RO, and distillation to mention a few.
Each has it's place, with the attendant advantages and disadvantages.
Reverse osmosis is capable of relatively high production rates and semi-automated operation with low energy expenditure and in a compact package.
An RO setup isn't something you will carry with you if you BO on foot [except for some very compact specialized units that still probably wouldn't be practical], but if you have to be holed up in your home or camp for an extended time, OR if the available water is contaminated in such a way that smaller hand filters or tablets don't make it suitable for drinking, RO might be the way to go.
EBay has complete portable RO systems that will almost fit into a large lunch bucket, I'm holding one now. It weighs about 5 pounds.
Here's a link from a random serch of eBay that will expire a week from now, so you can just search for portable reverse osmosis
cgi.ebay.com/New-Portable-4st-100GPD-Reverse-Osmosis-RO-Water-Filter_W0QQitemZ120054902542QQihZ002QQcategoryZ206 84QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
and another:
cgi.ebay.com/MWS-PORTABLE-REVERSE-OSMOSIS-WATER-FILTER-100-GPD-NEW_W0QQitemZ280049965616QQihZ018QQcategoryZ20684Q QssPageNameZWDVWQQrdZ1QQcmdZViewItem
To save me a lot of typing and time, here's a link to the basic principles of RO.
Here's what the RO element looks like in home units:
TYPICAL RO UNDER-COUNTER UNIT
The next links show a typical home RO unit. Notice it looks COMPLICATED, at least I thought so until I spent hours researching the issue incl talking to 'experts' who sell the units on eBay to learn the ins and outs. BTW, take the $$$ with a grain of salt, they're full retail.
MULTIPLE RO MEMBRANES IN SERIES
The following link is a way for advanced users to increase the water output without requiring additional expenditure of energy [I'm thinking total SHTF here, no electrical outlet, no well pump, you have to go out, collect water from a ditch or pond, and purify it to stay alive].
This multiple RO membrane cartridge concept is one I hadn't considered before and this might not be the right sequence in this discussion to present it, so don't forget abt it and be sure to come back and review it later if you choose to pursue this.
It simply involves connecting two or more RO filters in series and feed the output purified H2O to the same tank. [I'd use separate containers in case there was a problem w/ one of the RO filters and so I could monitor each filter's output.] I'll go into more detail about this option later.
urila.tripod.com/Seawater.htm
MODULAR
Lots of nice pix, what's an RO system. It really simple, but look at all the hoses, tubes, cartridges, tanks, etc, etc, looks like a rats nest.
Most of the components of an RO system are modular for easy installation and servicing.
The white cartridges are standardized and most have caps that unscrew so you can quickly replace the inner filter. Some are throw away.
All those little white tubes connect to quick attach fittings installed in each cartridge, to remove them, you push or pull w/ your fingers on a small ring and the tube slips out, to replace the tube push it firmly into the fitting.
The fittings appear reliable long term, and make service of the filters, and up-grading the system, quick and easy.
The cartridges are all in series. In seconds you could switch tubing around and modify the system.
TYPICAL RO SYSTEM
The RO 'undercounter' system consists of several prefilters, first a filter of yarn or something to filter out sediment, dirt, etc, so the following filters doing get clogged up any more quickly than they have to.
Next, a carbon [charcoal] filter is usually included to clean up chemicals and make the finished water taste better.
Maybe another carbon filter is included in the loop.
Some have an 'ion bed' resin bead cartridge that looks like a regular cartridge and has end caps that unscrew so you can dump out the old resin beads[abt the size of BB's] and fill it back with new ones after a few thousand gallons or so. Some of these cartridges are clear and the resin beads turn color when they need to be changed out.
The resin filter is useful if you have water that is real hard. Using one long term in a SHTF might be a good way to help prevent kidney stones.
Then on to the reverse osmosis RO cartridge, the most complex, yet simple, part of the system.
Finally a final 'polishing' filter of activated carbon and maybe a UVC [ultraviolet C light] purifier that kills any bugs that make it thru the whole system [more about that and some pix at the end].
DIRTY SECRET
It takes water under at least 45 PSI pressure [preferably 60 PSI] at the input of the RO membrane to make the RO system work.
Only about 1/5 of the water is actually forced thru the RO element, the rest is 'waste' and can be salvaged to run thru another filter, chlorinated in the normal way hikers do, or used for non-potable purposes.
The waste water is the dirty secret of RO filters, unfortunately it is a necessary factor in their operation.
Now, see the paragraph above where multiple RO filters can be put in series so a lot more of the 'waste' water can be purified. In practice, just get some extra tubing and quick connect 't's, plumb more RO filters into the system and collect more purified water.
The beauty is that you don't have to expend significantly more energy pressurizing the input water to 45+ PSI when putting multiple RO membranes in series and you get more purified water.
BUGS
Another factor you don't see up front in the RO literature. RO filters aren't guaranteed or spec'd to remove virii or bacteria, due to the fact that the membrane might not be perfect and might have tiny pinholes from the manufacturing process that the little critters can get through.
So, you will have essentially pure water coming out of the RO system, but it might have critters in it, not many though.
Depending on your water source, you might choose to chlorinate, use water purification tabs, or, my preference, UVC light purification, for absolute purity.
So why use RO in the first place if you have to purify the output product? Good question.
First, the output from even a small RO unit will process 1000's of gallons of water and even though the manufacturer says the output may have bugs in it, it is probably as clean as your tap water, you just can't take a chance.
You probably will need to use a fraction, if any, of the qty of chlorine or other chemicals to do the final purification.
But it depends on your water source, if its dirty tap water that's already been chlorinated and just has chemicals in it, this step might not be necessary.
NOTE: If the water is contaminated with chemicals and unknowns, a hand water filter isn't going to do the trick and probably only the RO process will get you water.
RO is cheap and simple once you understand it, is less labor intensive than using a hand filter and produces a lot more water for a long period of time.
Other techniques, purification tablets, hand filters, etc, may be more optimum in a given situation, so why not have all of the above options available and understand how to use them.
THE TANK
What is the tank that most of the Sam's, Costco, HD, Lowe's, eBay, systems come with?
It's a collector tank and looks like a small propane tank. This tank has a rubber diaphram inside it that has pressurized air on one side and a water inlet on the other. It's used to collect the purified water in a normal application, store the water, and deliver it from a small faucet on your sink on demand.
Another secret, that is actually in the favor of emergency water production, is the efficiency of the RO element is greatly reduced [meaning a whole lot more 'waste' water is released from the RO filter] as the RO output pressurizes the accumulator tank.
In other words, the pressure differential across the RO membrane becomes less as the membrane output sees a higher pressure in the storage tank as it fills with more and more water.
The greater the pressure differential, the more efficient the membrane vs the production of the 'waste' bypass water.
In an emergency, we can stop being soccer moms and dads getting our water from a faucet on our granite counter top and instead feed the output of the RO unit into a plastic container [with no back pressure] and go drink Katrina style and maximize the pressure differential across the RO membrane.
PRESSURE
How do we get 45+ PSI of pressure to feed the RO system? [60PSI is optimum]
Several ways, if you have a steep hill or a tall building, [since every 32 feet equal's about 15 PSI], and you can get your water 100+ feet above your RO system, you can pressurize it with gravity.
Another way is to use the accumulator tank that is provided with the RO kit. Fill the water side with water, pressurize the other side of the tank with a battery operated tire compressor or a hand tire pump and top off the pressure once in a while until the tank's water side is near empty. Repeat.
If you have the resources to have a larger 'well tank accumulator' [ about $100 and up at hardware stores] that can hold 10 or more gallons, your system can run unattended most of the time.
My choice is a small accumulator tank like are used in RV's and a 12VDC RV water pump, the smallest available. That will make a pretty much fully automatic system.
ULTRA-VIOLET FINAL PURIFICATION
Search UVC filter on eBay:
cgi.ebay.com/uv-water-filter-ultraviolet-purifier-reverse-osmosis-ro_W0QQitemZ4402388447QQihZ001QQcategoryZ20684QQrd Z1QQssPageNameZWD1VQQcmdZViewItem
That's one I ran across first, it's stainless steel and a lot more expensive than the plastic ones.
Here's a cross sectional view of what's in one, pretty simple and you could make your own in a pinch with a germicidal tube, outer plastic tube sealed to the former with a hi-tec adhesive.
cgi.ebay.com/UV-water-filter-ultraviolet-purifier-reverse-osmosis_W0QQitemZ4424873950QQihZ001QQcategoryZ2068 4QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
Note that these links will expire, if so search eBay ultravio* water*
The UVC filters sold on eBay, at hardware stores and pool suppliers are extremely effect in killing every organism in clear water.
EBay did have, maybe still does, search, some units for about $40 that are about 10 inches long, weigh about a pound and are well made. I couldn't believe the quality and design.
The are supplied with a wall-wart for power to run an 8 watt UVC flourescent lamp. Similar to the ones in a camp lantern or in an RV overhead light except these radiate UVC [hazardous so don't expose yourself to one].
The trick to using them in a SHTF is to get a solid state ballast for a similar flourescent lamp, HD has portable closet lamps that run on AA batteries, and wire two wires to the UVC tube.
The power requirements are minimal vs. the amount of water that is processed.
The combination of an RO system, a resin bed filter, and a UVC lamp assembly results in a 10 pound purification package that with some common sense, will purify 1000's of gallons of water, from the filth in Katrina to the alkaline stuff you can find in the desert.
Here's a write-up on Reverse Osmosis, RO, water purification, in the context of application in a SHTF senario.
First, there are many ways to make water safe to drink, hiking type hand pumps, water purification tablets, chlorine [bleach], boiling, RO, and distillation to mention a few.
Each has it's place, with the attendant advantages and disadvantages.
Reverse osmosis is capable of relatively high production rates and semi-automated operation with low energy expenditure and in a compact package.
An RO setup isn't something you will carry with you if you BO on foot [except for some very compact specialized units that still probably wouldn't be practical], but if you have to be holed up in your home or camp for an extended time, OR if the available water is contaminated in such a way that smaller hand filters or tablets don't make it suitable for drinking, RO might be the way to go.
EBay has complete portable RO systems that will almost fit into a large lunch bucket, I'm holding one now. It weighs about 5 pounds.
Here's a link from a random serch of eBay that will expire a week from now, so you can just search for portable reverse osmosis
cgi.ebay.com/New-Portable-4st-100GPD-Reverse-Osmosis-RO-Water-Filter_W0QQitemZ120054902542QQihZ002QQcategoryZ206 84QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
and another:
cgi.ebay.com/MWS-PORTABLE-REVERSE-OSMOSIS-WATER-FILTER-100-GPD-NEW_W0QQitemZ280049965616QQihZ018QQcategoryZ20684Q QssPageNameZWDVWQQrdZ1QQcmdZViewItem
To save me a lot of typing and time, here's a link to the basic principles of RO.
Here's what the RO element looks like in home units:
TYPICAL RO UNDER-COUNTER UNIT
The next links show a typical home RO unit. Notice it looks COMPLICATED, at least I thought so until I spent hours researching the issue incl talking to 'experts' who sell the units on eBay to learn the ins and outs. BTW, take the $$$ with a grain of salt, they're full retail.
MULTIPLE RO MEMBRANES IN SERIES
The following link is a way for advanced users to increase the water output without requiring additional expenditure of energy [I'm thinking total SHTF here, no electrical outlet, no well pump, you have to go out, collect water from a ditch or pond, and purify it to stay alive].
This multiple RO membrane cartridge concept is one I hadn't considered before and this might not be the right sequence in this discussion to present it, so don't forget abt it and be sure to come back and review it later if you choose to pursue this.
It simply involves connecting two or more RO filters in series and feed the output purified H2O to the same tank. [I'd use separate containers in case there was a problem w/ one of the RO filters and so I could monitor each filter's output.] I'll go into more detail about this option later.
urila.tripod.com/Seawater.htm
MODULAR
Lots of nice pix, what's an RO system. It really simple, but look at all the hoses, tubes, cartridges, tanks, etc, etc, looks like a rats nest.
Most of the components of an RO system are modular for easy installation and servicing.
The white cartridges are standardized and most have caps that unscrew so you can quickly replace the inner filter. Some are throw away.
All those little white tubes connect to quick attach fittings installed in each cartridge, to remove them, you push or pull w/ your fingers on a small ring and the tube slips out, to replace the tube push it firmly into the fitting.
The fittings appear reliable long term, and make service of the filters, and up-grading the system, quick and easy.
The cartridges are all in series. In seconds you could switch tubing around and modify the system.
TYPICAL RO SYSTEM
The RO 'undercounter' system consists of several prefilters, first a filter of yarn or something to filter out sediment, dirt, etc, so the following filters doing get clogged up any more quickly than they have to.
Next, a carbon [charcoal] filter is usually included to clean up chemicals and make the finished water taste better.
Maybe another carbon filter is included in the loop.
Some have an 'ion bed' resin bead cartridge that looks like a regular cartridge and has end caps that unscrew so you can dump out the old resin beads[abt the size of BB's] and fill it back with new ones after a few thousand gallons or so. Some of these cartridges are clear and the resin beads turn color when they need to be changed out.
The resin filter is useful if you have water that is real hard. Using one long term in a SHTF might be a good way to help prevent kidney stones.
Then on to the reverse osmosis RO cartridge, the most complex, yet simple, part of the system.
Finally a final 'polishing' filter of activated carbon and maybe a UVC [ultraviolet C light] purifier that kills any bugs that make it thru the whole system [more about that and some pix at the end].
DIRTY SECRET
It takes water under at least 45 PSI pressure [preferably 60 PSI] at the input of the RO membrane to make the RO system work.
Only about 1/5 of the water is actually forced thru the RO element, the rest is 'waste' and can be salvaged to run thru another filter, chlorinated in the normal way hikers do, or used for non-potable purposes.
The waste water is the dirty secret of RO filters, unfortunately it is a necessary factor in their operation.
Now, see the paragraph above where multiple RO filters can be put in series so a lot more of the 'waste' water can be purified. In practice, just get some extra tubing and quick connect 't's, plumb more RO filters into the system and collect more purified water.
The beauty is that you don't have to expend significantly more energy pressurizing the input water to 45+ PSI when putting multiple RO membranes in series and you get more purified water.
BUGS
Another factor you don't see up front in the RO literature. RO filters aren't guaranteed or spec'd to remove virii or bacteria, due to the fact that the membrane might not be perfect and might have tiny pinholes from the manufacturing process that the little critters can get through.
So, you will have essentially pure water coming out of the RO system, but it might have critters in it, not many though.
Depending on your water source, you might choose to chlorinate, use water purification tabs, or, my preference, UVC light purification, for absolute purity.
So why use RO in the first place if you have to purify the output product? Good question.
First, the output from even a small RO unit will process 1000's of gallons of water and even though the manufacturer says the output may have bugs in it, it is probably as clean as your tap water, you just can't take a chance.
You probably will need to use a fraction, if any, of the qty of chlorine or other chemicals to do the final purification.
But it depends on your water source, if its dirty tap water that's already been chlorinated and just has chemicals in it, this step might not be necessary.
NOTE: If the water is contaminated with chemicals and unknowns, a hand water filter isn't going to do the trick and probably only the RO process will get you water.
RO is cheap and simple once you understand it, is less labor intensive than using a hand filter and produces a lot more water for a long period of time.
Other techniques, purification tablets, hand filters, etc, may be more optimum in a given situation, so why not have all of the above options available and understand how to use them.
THE TANK
What is the tank that most of the Sam's, Costco, HD, Lowe's, eBay, systems come with?
It's a collector tank and looks like a small propane tank. This tank has a rubber diaphram inside it that has pressurized air on one side and a water inlet on the other. It's used to collect the purified water in a normal application, store the water, and deliver it from a small faucet on your sink on demand.
Another secret, that is actually in the favor of emergency water production, is the efficiency of the RO element is greatly reduced [meaning a whole lot more 'waste' water is released from the RO filter] as the RO output pressurizes the accumulator tank.
In other words, the pressure differential across the RO membrane becomes less as the membrane output sees a higher pressure in the storage tank as it fills with more and more water.
The greater the pressure differential, the more efficient the membrane vs the production of the 'waste' bypass water.
In an emergency, we can stop being soccer moms and dads getting our water from a faucet on our granite counter top and instead feed the output of the RO unit into a plastic container [with no back pressure] and go drink Katrina style and maximize the pressure differential across the RO membrane.
PRESSURE
How do we get 45+ PSI of pressure to feed the RO system? [60PSI is optimum]
Several ways, if you have a steep hill or a tall building, [since every 32 feet equal's about 15 PSI], and you can get your water 100+ feet above your RO system, you can pressurize it with gravity.
Another way is to use the accumulator tank that is provided with the RO kit. Fill the water side with water, pressurize the other side of the tank with a battery operated tire compressor or a hand tire pump and top off the pressure once in a while until the tank's water side is near empty. Repeat.
If you have the resources to have a larger 'well tank accumulator' [ about $100 and up at hardware stores] that can hold 10 or more gallons, your system can run unattended most of the time.
My choice is a small accumulator tank like are used in RV's and a 12VDC RV water pump, the smallest available. That will make a pretty much fully automatic system.
ULTRA-VIOLET FINAL PURIFICATION
Search UVC filter on eBay:
cgi.ebay.com/uv-water-filter-ultraviolet-purifier-reverse-osmosis-ro_W0QQitemZ4402388447QQihZ001QQcategoryZ20684QQrd Z1QQssPageNameZWD1VQQcmdZViewItem
That's one I ran across first, it's stainless steel and a lot more expensive than the plastic ones.
Here's a cross sectional view of what's in one, pretty simple and you could make your own in a pinch with a germicidal tube, outer plastic tube sealed to the former with a hi-tec adhesive.
cgi.ebay.com/UV-water-filter-ultraviolet-purifier-reverse-osmosis_W0QQitemZ4424873950QQihZ001QQcategoryZ2068 4QQrdZ1QQssPageNameZWD1VQQcmdZViewItem
Note that these links will expire, if so search eBay ultravio* water*
The UVC filters sold on eBay, at hardware stores and pool suppliers are extremely effect in killing every organism in clear water.
EBay did have, maybe still does, search, some units for about $40 that are about 10 inches long, weigh about a pound and are well made. I couldn't believe the quality and design.
The are supplied with a wall-wart for power to run an 8 watt UVC flourescent lamp. Similar to the ones in a camp lantern or in an RV overhead light except these radiate UVC [hazardous so don't expose yourself to one].
The trick to using them in a SHTF is to get a solid state ballast for a similar flourescent lamp, HD has portable closet lamps that run on AA batteries, and wire two wires to the UVC tube.
The power requirements are minimal vs. the amount of water that is processed.
The combination of an RO system, a resin bed filter, and a UVC lamp assembly results in a 10 pound purification package that with some common sense, will purify 1000's of gallons of water, from the filth in Katrina to the alkaline stuff you can find in the desert.
Comment