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Author Topic: More Fresh water while Boondocking?  (Read 4255 times)

Cant Wait

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More Fresh water while Boondocking?
« on: October 29, 2013, 06:37:07 AM »
Being as a Reverse Osmosis Water Purification Unit can take ANY water and purify it for drinking has anyone considered using one of these units to recycle GREY water to Fresh Water tank and extend the interval between dumping Grey Tanks and needing to refill the Fresh Water tank?
2012 Winnebago "Our Incredible Journey"  40U
2008 Dakota Sport 4x4
2004 Subaru Baja - DW's
2005 Honda Shadow Aero - TOAD for now
Home - Western NY

kjansen

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Re: More Fresh water while Boondocking?
« Reply #1 on: October 29, 2013, 07:08:06 AM »
I haven't tried this, but would think the filter would plug up faster.  I have also read someplace that for every gallon of RO water you get, 2 gal is wasted down the drain.  If that is the case you couldn't  recover a lot of water and you have to use a pump to get pressure to filter the water.
Keven Jansen
'06 Chevy 2500 Duramax
'02 Montana Big Sky
Alexandria, Mn

Jeff

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Re: More Fresh water while Boondocking?
« Reply #2 on: October 29, 2013, 10:51:04 AM »
We use RO in Az but I am not sure I have that much confidence in the filter system.  As was mentioned we do not have it in the m/h because of the amount of water it wastes.

Ned

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Re: More Fresh water while Boondocking?
« Reply #3 on: October 29, 2013, 11:10:34 AM »
Route the excess water from the RO unit back to the fresh water tank.  As you use water from the tank, replenish it with fresh water and the mineral concentration won't get too high and you won't waste any water.
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon

Jeff

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Re: More Fresh water while Boondocking?
« Reply #4 on: October 29, 2013, 11:24:18 AM »
Ned the question was using RO for grey water, not fresh water. I am not sure you want to route the excess water into your fresh water tank.

Ned

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Re: More Fresh water while Boondocking?
« Reply #5 on: October 29, 2013, 11:54:40 AM »
I know, but most RO installations throw away perfectly good fresh water.  I wouldn't reuse the gray water either and wouldn't even try to run it through an RO unit.
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon

Lou Schneider

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Re: More Fresh water while Boondocking?
« Reply #6 on: October 29, 2013, 03:37:22 PM »
You have to use a fair amount of non-RO water to let you recycle the RO brine back into the fresh water tank.

If you get all or most of your water from the RO unit, the tank won't empty fast enough to let you add enough water to dilute the brine before it gets to dangerous levels.

Ned

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Re: More Fresh water while Boondocking?
« Reply #7 on: October 29, 2013, 03:58:00 PM »
Lou, even if you feed the RO unit from the fresh water tank?
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon

Lou Schneider

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Re: More Fresh water while Boondocking?
« Reply #8 on: October 29, 2013, 06:07:19 PM »
An RO unit doesn't waste "fresh" water - it's waste is a brine that has increased it's percentage of dissolved solids by the percentage of clean water it produces.

If you waste 2 gallons for every 1 gallon of RO water production, the brine concentration returning to the tank will be 1/3 higher than what you started with.

Drawing down the tank further increases the concentration.  If the RO unit is returning all of the dissolved solids to the tank, at 1/2 tank the concentration has doubled from the the starting point.   At 1/4 tank the concentration has quadrupled.  You'd have to refill the tank with distilled water to return the dissolved solids to their original levels - anything else just adds more contaminates to the tank, further increasing the load on the RO unit.

Do this enough times in a row and you can wind up with concentrated brine in your fresh water tank.

Using some non-RO water slows the buildup because you're processing more water through the tank, diluting the brine to some extent.  And you pull some of the pull some of the dissolved solids out of the loop as you use the non-treated water. 

It's a tradeoff - clean water for drinking, more concentrated brine for your other uses.
« Last Edit: October 29, 2013, 06:11:38 PM by Lou Schneider »

ArdraF

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Re: More Fresh water while Boondocking?
« Reply #9 on: October 29, 2013, 06:16:47 PM »
Quote
has anyone considered using one of these units to recycle GREY water to Fresh Water tank

We have R.O. water in the stick & brick and love it, but it's really only practical in an RV if you park for long periods and can hook up to fresh water which can go through the R.O. unit.  We talked about adding one and decided it wasn't practical for us because we move so frequently.  As to using gray water, I wouldn't because of all the food debris from kitchen sinks and hair from bathroom drains.  I suspect it would all clog the filters very quickly.

If you're worried about having good drinking water from uncertain sources we've always used a preliminary filter for large particles (we've seen leaves in water tanks) at the campground water faucet.  Then we have other filters in the RV that go to smaller particles.  The final one is under the kitchen sink and it removes particles down to 5 microns which takes care of giardia and cryptosporidium.  We've used these filters for many years and never had any issues, including down in Mexico where everyone else in the group got sick.  If you set up the filters properly and make sure you have the best, you'll be okay.

ArdraF
« Last Edit: October 29, 2013, 06:22:07 PM by ArdraF »
ArdraF
:D :D

JiminDenver

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Re: More Fresh water while Boondocking?
« Reply #10 on: October 29, 2013, 06:44:54 PM »
You could re-purpose the grey water for flushing the toilet.

kjansen

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Re: More Fresh water while Boondocking?
« Reply #11 on: October 29, 2013, 06:55:07 PM »
Arda,
I may be wrong but you have to get 0.5microns to filter out giardia and other  microbes. 
Keven Jansen
'06 Chevy 2500 Duramax
'02 Montana Big Sky
Alexandria, Mn

ArdraF

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Re: More Fresh water while Boondocking?
« Reply #12 on: October 29, 2013, 07:19:21 PM »
Ooops!  Yes.  It's 0.5 not 5 microns.  Big difference in the world of bugs!  :-[  Thanks for catching that.

ArdraF
ArdraF
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millermarine

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Re: More Fresh water while Boondocking?
« Reply #13 on: February 28, 2015, 10:54:38 PM »
I am a marine Electrician and have worked on many RO machines that convert sea water to fresh water.  A RO unit with pre filters should work to clean grey water.   the water used by RO machine is simply put back into the grey water tank.  I don't even have a RV yet I want to build a Schoolie. 

rvpuller

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Re: More Fresh water while Boondocking?
« Reply #14 on: March 01, 2015, 06:01:03 AM »
Another problem if your doondocking how do you plan on powering your water pump, the RO systems needs constant pressure on the inlet side to work.

We've had one for 9 years for drinking water only and wouldn't be without it again, we bank water in gal jugs when traveling.

Denny
35 FKTG HH Premier  215/75/17.5 tires. 13" Kodiak Disks
2013 F350 DRW 6.2 V8 4.30 gears
Home Base SC Nebraska

blw2

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Re: More Fresh water while Boondocking?
« Reply #15 on: March 01, 2015, 06:09:43 AM »
Not that I would want to unless I camped where fresh water was very hard to come by and I had a limited capacity, but I'll bet that if you put a series of strainers or bag filters ahead of the RO filter, you could make it work.  I think you'd have to have a process or system to dump the salts periodically.  Maybe even measure them so you'd know when it was time to flush them out.....

Maybe you could use the waste to flush the toilet or dilute the black water

Hey, now that I'm thinking about it.... my grey tank is my limitation, as it's too small.  Might be a way for me to stretch my "legs" a bit...... nah, I think it's not worth the expense or trouble in my case....
Brad (DW + 3 kids)
13 Thor Chateau 31L Class C on Ford E-450
'06 Silverado
'05 Rockwood Freedom 1910 (5-1/2 years)
former tent campers

 

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