Low power potable water filtration?

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Small Cabin Forum / Off-Grid Living / Low power potable water filtration?


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torque Member	# Posted: 4 Mar 2012 14:18 - Edited by: torque Reply Hello everyone. I am in the midst of planning a self-sustainable earthbag type of home. I am a plumber in Canada so I have a pretty thorough understanding of what can be done with water. The only problem is most of my training has been based around ample electricity, and huge pumps. A lot of commercial systems rely on the grid for their marvelous filtration. I'm designing a home that really only needs electricity for two things, a chest style refigerator, and a chest style freezer. Those will be needed for sure. I figure I can run these at 400kWh year. A solar set up for something like this won't be too pricey. I plan to buy the panels needed for these, and then add maybe one or two more for utility such as charging cell, laptop, camera, and possibly running LED lights. I'd be okay with daylight/candles. So with that said, I am trying to figure into my design if I need to acquire enough solar panels to run a small pump type system to make a RO membrane feasible. Either that or running something like a carbon filter with a water ionizer. I am curious if any of you guys who have more experience with offgrid than I do could offer any suggestions? A 1/6 hp Ridgid utility pump runs on 2.5 amps, or 300 watts. I'd really only need to turn it on when I needed to force water through a membrane. Although I'd still need to make sure I had about a minimum of 30psi. The rest of my water I plan to have rainwater collection, and a solar water heater. I will run all my drains into a greywater filter box, and then run a piece of tubing 100feet or so to a rain barrel for watering my plants. I will use a composting toilet. So really the only thing I can't figure out yet is if I need enough electricity to make RO feasible (due to pressure) or if there is a work around I haven't figured out yet. I'd need a 40' high column of water to generate 17~ psi from head pressure. A tank that could hold potable water this size seems prohibitive due to price. Thank you in advance! Edit: I should say, I don't plan on doing this in the extreme climates of Canada. I plan to move to Ecuador. I also do not want to rely on any kind of petroleum products. I can't believe people switch away from the "grid" and then turn to these. It's just six in one half a dozen in the other in my opinion. Electric companies are far less evil than oil companies! And on the same note as petroleum products, I don't want to mess around with consumables like iodine, bleach, or activated carbon if I don't have to. I understand membranes don't last forever either but I believe they are the longest lasting type of consumable. If I am wrong please fill me in on the subject haha.

MtnDon Member	# Posted: 4 Mar 2012 15:10 Reply How about a Berkey water filter? No power needed at all. I like UV light purification after a sediment filter, but they do require electricity. Possible to run off solar though.

Just Member	# Posted: 4 Mar 2012 15:12 Reply I prefilter rainwater with a gravity fed sand filter before it enters storage .then pump into cabin with a 12 volt rv water pump.The pump easely maintains 40 lb.that and a 2 gal. blader tank would run a membrain filter ,[we use bleach] but like your style !!!not sure how many watts a Flow Jet Pump needs ..

torque Member	# Posted: 4 Mar 2012 15:24 - Edited by: torque Reply Whoa I was just looking at those types of pumps Just! http://www.northerntool.com/shop/tools/product_37142_37142?cm_sp=Upsells-_-Top%20Sell ers-_-Product%20Page So yeah if I can power that at 96 watts and get 40 psi (I'd be happy with 30!) then I can definitely have a potable kitchen sink I will have the typical KDF shower filter on my showerhead, and possibly rig one up under my lavatory sink cabinet. I don't NEED potable water to wash my face or hands but for how easy it is to install I might as well. I will put the pump and RO equipment under my kitchen sink. I'd have to figure out a way to run the solar water heater line into the RO without it losing temperature to have hot water at my kitchen sink. But at the end of the day if I had cold potable water at the sink that's all I really need for cooking. After quickly thinking about it having another one of those showerhead KDF filters underneath my sink after the RO and before the faucet would solve all my problems. (Cold potable water for drinking/washing vegetables, and hot KDF filtered water for doing dishes) This is becoming more and more feasible everyday The solar water heater I plan to build will be one of those large boxes that's insulated and has an old-school water heater painted black. I've seen prototypes on youtube that the water can get to 180F on a sunny day!! Crazy. I'd need to use a mixing valve in my shower haha. I will check out the Berkey filter as well MtnDon. Thank you guys. I am pretty excited about this whole plan coming together.

TomChum Member	# Posted: 5 Mar 2012 11:10 - Edited by: TomChum Reply Quoting: torque I don't NEED potable water to wash my face or hands Fun project. I suppose it might depend what is in the water To conserve membranes can you add an outlet after the main filters, but before the membrane? This outlet might flow on head pressure, thus allow you to get partially filtered water without using electricity. And reduced usage could get longer life from the membrane, if used only for drinking water.

torque Member	# Posted: 5 Mar 2012 20:49 - Edited by: torque Reply Hey Tom, thanks for adding to the topic! I am not sure what you mean by "outlet"? Could you elaborate? From what I understand the minimum for most RO membranes is 30~ psi. The higher your PSI the less water you waste converting it into RO. For people who have unlimited tap water they obviously don't worry about this so much, but I wouldn't want to use twice as much rainwater just so I don't have to power a (small load) RV pump. They make things called ultra low pressure membranes (ULPRO), although I haven't checked into the prices of them and I'd imagine they'd be more expensive, as anything specialized nowadays is. If I understand your question you're asking if I could bypass the membrane filter and use just the carbon/sand filters first? That's kind of what I had described with one of my last posts. I have to check what kind of pressure is needed for the KDF style filters as they are designed as shower heads which again, usually have a minimum of 30psi. When I first installed mine I didn't understand how it worked because it has a hole in the middle and it looked as if water would just take the easiest route (as it always does), through the middle and not go through the filter, but on closer inspection the water seems to back up because of the shower head (they are designed to save water, they run at roughly half the gpm as a tub spout does). So I'd have to kind of test these in my situation and then test the water to see if the results were adequate. Thanks for getting the wheels spinning in my head, it's much appreciated. Edit: Just wanted to add that normal life on a RO membrane is 5 years. The carbon filters if you choose to use them are 6~ months. Those berkey filters sound great on paper. Although after checking out the prices of the unit itself and then the replacement filters... no thanks. Not a fan of proprietary stuff for that reason - price gouging. The prices I'd spend on purchasing and maintaining these would be much better spent on an extra solar panel or battery in my opinion.

TomChum Member	# Posted: 5 Mar 2012 21:10 Reply I meant you put a "Y" after the sand+carbon and if you open a valve after that Y, the water flows out,possibly by gravity, partially filtered, but not RO'd. Allows you to reduce the usage of the RO ( and thus reduce the wastewater too ).

torque Member	# Posted: 5 Mar 2012 21:17 - Edited by: torque Reply Okay, I see what you mean. To be honest I don't have a "fully designed" system yet. When I posted my first post I was still unsure if all this was possible. Now that I know what's out there I am going to take a few days and draw up some different piping routes to see what I can come up with. I will post my finished design when I am happy with it for anyone curious. If I can get drawings onto the computer I will, I don't really like drawing stuff with software, as I'm used to quick isometric drawings on site Edit - If anyone has experience with using these RV style pumps for long distances I'd be interested to hear in how they hold up with the PSI. I know a 90degree fitting contributes as much friction as 10ft of piping. So I will take my time to design this with as little friction as possible. Plastic pipes ahoy~ I think I am planning to put the RV pump up top near my cisterns so that every line I run will be pressurized. Should work out well. Really appreciate all the suggestions and questions! Don't hesitate to ask anymore guys!

TomChum Member	# Posted: 5 Mar 2012 21:20 - Edited by: TomChum Reply Quoting: torque as I'm used to quick isometric drawings on site ...on a piece of 2x6....

torque Member	# Posted: 5 Mar 2012 21:23 Reply I always break my pencils on wood, lol! I'm a priss and use the wholesaler notepads, love 'em! :P

Rob_O	# Posted: 5 Mar 2012 22:33 Reply Quoting: torque Those berkey filters sound great on paper. Although after checking out the prices of the unit itself and then the replacement filters... no thanks. You can get a pair of the filter elements for $100 on eBay. Another $10 for 2 buckets and a lid and you have 6000 gallons of drinking water. For the rest of your household water, filter the solids out and hit it with some bleach. Bleach is expensive and has a short shelf life, pool shock is cheap and stable and a few grams is all you need to make a gallon of bleach. Keep it dry and a few bucks worth will last you a long, long time Hope that helps, good luck with the project!

torque Member	# Posted: 6 Mar 2012 00:31 Reply Sorry, but you didn't really read my posts I guess. Shipping off a site like ebay to a rural area in Ecuador isn't as easy as it is to a cabin in the states. It's hard to get any type of parcel anywhere other than a major city like Quito. So this right away poses problems. I clearly stated that I didn't want to rely on consumables. Especially one like bleach, which is a proven neurotoxin. Again, going off-grid and then relying on products created by an industrial process seems so counter-productive to me.

MtnDon Member	# Posted: 6 Mar 2012 00:37 Reply Quoting: torque Edit - If anyone has experience with using these RV style pumps for long distances I'd be interested to hear in how they hold up with the PSI. Not sure what makes a "long distance" to you, but I have a run of about 35 feet to a shower from the Shurflo pump we have. Both a hot and a cold run of 1/2" PEX with probably at least 6, maybe 8, brass 90 degree PEX fittings in each run. (cramped space). The pum p is rated at 45 psi and a flow of 2.8 gpm. I've never put the pressure gauge on it because the shower performance is fine. Flow drops if we run water at the kitchen sink at the same time but the shower still works. Shower has a 1.7 gpm head, IIRC. Note that Shurflo rates the pump at having the ability to lift 6 feet. Flow suffers in my experience though. The pump draws water from an under counter tank about 20 inches tall. I originally mounted the pump on top of the tank. Flow was not as good as the same pump in the RV. I moved the pump to sit at the level of the bottom of the tank. Better flow and less pump noise. The system holds pressure when the fixtures are off. I can't ever remember hearing the pump have to come on even briefly when the system sits for hours and hours with no water being drawn. Myself, I would be careful of using water for showering unless you were certain it was sanitary. There are some water borne nasties that can make you very ill if inhaled from a warm water mist.

Rob_O	# Posted: 6 Mar 2012 02:57 Reply Quoting: torque Sorry, but you didn't really read my posts I guess. I clearly stated that I didn't want to rely on consumables. Unless you've figured out a way to make RO membranes out of banana leaves, you are still relying on consumable products created by an industrial process and will still have all the same problems getting them from here to there. You also need to have a pump, batteries, power to charge the batteries and all the other stuff that can break for your RO system. The Berkey is a lump of ceramic mounted to a bucket that will work as long as gravity keeps going. The bleach is your choice, but as MtnDon noted their are waterborne nasties that can make it past a sediment filter Again, good luck with your project

torque Member	# Posted: 6 Mar 2012 04:26 - Edited by: torque Reply A membrane lasts 5 years. I could buy 4 and have 20 years worth of membranes in my suitcase. The thought of bringing 20 years worth of bleach in a suitcase is laughable. My parents would be visiting me often enough I'd never have to travel back to Canada to acquire more membranes. Yeah pumps can potentially break. I'd much rather fix a pump (being a plumber) and understanding cavitation and all the problems related to pumps. For what they are worth it wouldn't hurt to have 2 backups that aren't even installed just so I wouldn't have to tinker with them in the event that happens. I won't be in the states where yeah, pollution is at an all time high. I'd be comfortable showering/washing my face in pure rainwater like I said, if I had to. Batteries can blow up or "break" as you put it if not vented correctly. I've seen rat nests of battery boxes that I would never even live near. I need refrigeration, freezing, as well as utility for my laptop, cell and camera like previously stated. The load those pumps draw is insignificant in the grand scheme of things. Your beloved berkey filter also doesn't add anything to the rest of my plumbing design, ie pressure, which makes everything so much easier to live with. It'd be like I'm back at home as far as water supply goes. Gravity fed everything is a last resort as far as I am concerned when it comes to plumbing. Reading comprehension goes far on a forum - bringing up something I specifically said I don't want to deal with then trying to defend your point of view looks juvenile to say the least. I guess I struck a nerve. Edit - I never saw your post until now MtnDon. Thanks for the real life information regarding the pumps. Most houses in Canada if they were piped before 2000 lose pressure if more than 2 fixtures are running anyways. Can you elaborate on these "nasties" rather than just using a blanket term? Also while on the subject of airborne mist and water... check out chlorine. You guys are essentially gasing yourself like the nazis did but on a lesser scale. Nothing I would entertain myself personally, but to each their own. The more and more I read about this berkey filter the less I like. Everything they say hasn't been proven. "Years and years of research have gone into these filters..." Where's the papers citing said research? I spent 20 minutes looking online and it's all just websites who sell this crap trying to promote them. It says a filter lasts 8 years if you use 2 gallons of water a day. Where is this proven? 5 people who are going off about them were donated the filters, of course they're going to gush over them and hope for more in the future. RO has been around a lot longer and it's been tested by more than one source. Also their claims of flouride removal have been hotly contested it appears. Call it intuition but I don't like this filter for some reason. After more reading. a $110 dollar filter claims to filter 3000 gallons. If me and some dogs drink 4 gallons a day that's only 2 years at $110 dollars. This is all according to the information given by people who are profitting off this type of filter. If someone can show me unbiased research I would gladly change my opinion on these. They also have to be cleaned every 6 months. More maitenance. RO filters just sit in there for 5 years. One can be had for 50 dollars. So basically you'd have to spend $250~ on berkey filters to get the equivalent length of filtration time from a $50 dollar RO membrane. I can get wholesale prices of RO membranes, no deals on proprietary crap like the berkey filter. The RO needing pressure is a downside, but considering I'd throw in a pump to make it work, it'd cost less, and have less maintenance, it's not really a downside the way I see it. It is a boon having pressurized water lines. The price difference of $200~ could almost buy a 200watt solar panel (by the time I actually go to purchase them, probably the whole thing), or the 2 backup pumps, or whatever else I find useful. I've done institutional work as a plumber installing RO systems in hospitals. One site was an eye regenative medicine lab built in the General Hospital in Ottawa. Another was a military virtual reality room which was going to be tried out for rehabilitation patients to simulate walking around in a nice summer day in the middle of winter. If these filters were all the rage that they claim, I'm sure people would have been talking about them in these environments. As it stands I can only find literature stating it was tested at one university(and there is quite a drastic difference between a bona-fide research document, and saying it has been tested), which is in Arizona. I'd like to find out who designed this thing and where... and who would be profitting from backing it up at this university. It's been around since 2000 and still doesn't have a wikipedia entry? Come on guys, you're getting your eyes screwed out. Really trying hard to like this thing, just don't see it happening.

MtnDon Member	# Posted: 6 Mar 2012 10:39 - Edited by: MtnDon Reply I do not use or sell a Berkey filter so I have nothing to gain from suggesting Berkey filters. The attractive thing about them is that they require no onsite technical skills. No onsite technology other than the unit ityself. They are very popular among missionaries who venture to foreign lands and have to live in primitive conditions. Perfect for where there is no electrical power and the water comes out of a jungle stream. I suggested it because I got the impression, maybe mistakenly, in the OP that you were trying to keep high tech to a minimum. An RO on a rainwater system seems to be a water waster to me, but then I'm coming from a desert situation where water is at a premium. (8.5" annual precipitation) BTW, the missionaries using the Berkey don't get sick when they use them. I know that's anecdotal evidence, not scientific, but I don't care to do any research on it because I'm not the one looking for a system. I have my water. We RO drinking and cooking water at home; waste goes to irrigation. If I didn't use the waste water I would have personal problems with the waste. We have a UV system at the cabin in the mountains. Just FYI we filter out the chlorine for showers. We also go through at least one sediment filter a year plus a carbon filter. More expense. You have not mentioned them. Do you use a TDS meter, or plan to? I don't mind using technology; we have a small PV system (640 watts of panels) at the cabin and an extensive PV system at home (3.5 KW). Electricity is so handy. And I have a battery bank that is very tidy. Quoting: torque Reading comprehension goes far on a forum - bringing up something I specifically said I don't want to deal with then trying to defend your point of view looks juvenile to say the least. I guess I struck a nerve. And you will be striking more nerves with commentary like that. Sorry if not everyone who frequents forums is as brilliant as you think you are.

Rob_O	# Posted: 6 Mar 2012 10:42 Reply Quoting: torque Reading comprehension goes far on a forum Yes it does. For $110 you get 2 filters and a 5 lb box of pool shock will make enough bleach to treat 128,000 gallons of water while comfortably fitting in your suitcase For clarity, could you provide specifics on the RO system you plan to use?

torque Member	# Posted: 6 Mar 2012 11:52 - Edited by: torque Reply Sure, even at $50 dollars for a filter there are shipping charges as I can't buy it locally or in Ecuador. I was wrong about the price. I was more concerned about finding proper literature than price shopping on something I don't believe in yet. Pool shock and bleach still remain a neurotoxin. Sediment and charcoal filters can be made quite easily. Not the same with firing ceramic at 1000 degrees. The really fishy thing is the no wikipedia entry... after 12 years of this "fantastic" technology I'd imagine someone would do a write up about it... except all the writing has been done on personal websites who sell this stuff. I still haven't seen a document with proper testing. Yes I plan to use a TDS meter. I have one from long ago growing dope with some friends I don't claim to be brilliant - but you guys sure haven't persuaded me with this berkey thing. To be bluntly honest, I've gotten all the information I need from this forum. I wasn't aware of RV pumps and now I am. They have greatly improved my options for the plumbing designs I plan on and I thank you guys for that. I also don't plan to live alone for the rest of my life. I'd like to be able to host 10-20 people on my land if possible. If they had pets and each drank a gallon a day, the numbers get worse for the berkey filters. The desert climate is definitely a real concern about wasting water, and I understand that. Luckily the place I plan on doing this refers to seasons on how much water they get, and even a "dry" season has substantial rain compared to desert climates. RO is wasteful, especially at the pressures I plan to run it at. I won't dispute that, although there are plenty of ways to catch the wastewater and put it to other uses.

TomChum Member	# Posted: 6 Mar 2012 14:49 - Edited by: TomChum Reply Quoting: torque To be bluntly honest, I've gotten all the information I need from this forum. This thread was inspiring while it lasted. I suppose blunt is an appropriate word. Also note that many forums develop a natural social dynamic where if you get grumpy with someone who everyone else likes, then the good folks ignore you, and only the troublemakers will reply to you after that. Then you have to bail and go find another forum. Quoting: torque I also don't plan to live alone for the rest of my life. I'd like to be able to host 10-20 people on my land if possible. If they had pets and each drank a gallon a day, the numbers get worse for the berkey filters. Well well. With that in mind; my recommendation is to pursue the most economical single-person solution. 10-20 people is a lot, you might consider organizing them to bring stuff from Quito on their way.

Rob_O	# Posted: 6 Mar 2012 18:54 Reply Where are you Mr. torque? I want to hear the details on this Miracle system that will provide 60 gallons of drinking water per day for 5 years without changing the membrane (109,500 gallons). Please tell us who makes this wondrous device and where I can buy one.

torque Member	# Posted: 7 Mar 2012 00:00 - Edited by: torque Reply Haha 60 gallons a day... if I had 20 people that'd mean 3 gallons per person, that's 11~ litres? Water poisoning ahoy. You guys are just butthurt that you can't prove the berkey system to be all it's cracked up to be. I'm done, and I don't feel the need to divulge the system I am building anymore just because you guys have failed to produce any adequate information involving the berkey or why chlorine is such a god-send. Again... 12 years and no wikipedia entry? Are your eyes itchy? From how long the wool has been pulled over them. Adios amigos

MtnDon Member	# Posted: 7 Mar 2012 00:55 Reply Quoting: torque I don't feel the need to divulge the system I am building ... as small minded as he is obnoxious.

Rob_O	# Posted: 7 Mar 2012 01:51 Reply Quoting: torque I don't feel the need to divulge the system I am building anymore Apparently, you are as ignorant as you are arrogant, if you really were a plumber you would be able to back up your assertions.