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way2roll

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Posted: 09/30/20 01:11pm Link  |  Quote  |  Print  |  Notify Moderator

Bumpyroad wrote:

way2roll wrote:

All the impurities are collected in the filter membranes themselves and stored until exhausted and then replaced. So by recycling the "waste" water in an RO system you are simply continually trying to push the same water through the system until it finally makes it. It's not any dirtier than it was to start with - it just never got polished. .


if the waste water is returned to the supply tank or source that water will keep collecting reject material and get increasingly dirty and the efficiency of the membranes will suffer.
bumpy


I think you need to read my post again. Rejected/waste RO water has not been though the system. There's no "dirt" added - it never made it into the filter.


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Bumpyroad

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Posted: 09/30/20 04:15pm Link  |  Quote  |  Print  |  Notify Moderator

way2roll wrote:

Bumpyroad wrote:

way2roll wrote:

All the impurities are collected in the filter membranes themselves and stored until exhausted and then replaced. So by recycling the "waste" water in an RO system you are simply continually trying to push the same water through the system until it finally makes it. It's not any dirtier than it was to start with - it just never got polished. .


if the waste water is returned to the supply tank or source that water will keep collecting reject material and get increasingly dirty and the efficiency of the membranes will suffer.
bumpy


I think you need to read my post again. Rejected/waste RO water has not been though the system. There's no "dirt" added - it never made it into the filter.


i am assuming that the reject water is not dumped on the ground nor do you allow it to fill up your grey water tank but reintroduce it to the supply tank. that is the one problem with RO, an excessive amount of water is rejected and if not reclaimed, wasted.
bumpy





ksg5000

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Posted: 09/30/20 04:16pm Link  |  Quote  |  Print  |  Notify Moderator

I use RO system for my Saltwater fish tank ... IMO it's impractical for boondocking because it take a a great deal of water pressure and much of the water is discarded. Remember - when boondocking your stuck with limited energy, water supply, and waste storage capacity.


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Posted: 09/30/20 05:35pm Link  |  Quote  |  Print  |  Notify Moderator

TechWriter wrote:

The main drawback of RO systems is waste water. An RO filter will "reject" a lot of water. However, I just plumb the RO waste water back into my RV's water tank.

ToastHater wrote:

That's exactly what I was thinking. I'm just not sure if that will cause more damage in the long run. Running all of the waste through the system repeatedly. Causing the maintenance/replacement cycles to be more frequent.

Bumpyroad wrote:

recirculating waste (dirty) water back into the feed water system would make that water dirtier and dirtier wouldn't it? what does that do for efficiency.
bumpy


RO 101

The system I and other RVers have are under-the-sink RO units for drinking water. I've only heard from a few RVers who have "whole RV" RO systems in which ALL water going into the RV passes through an RO system. The latter is wasteful, slowwwwwwwwwww, and hardly suited to RVing, much less boondocking.

Anyway, about RO "waste" water, also called brine. First, before water from outside your RV hits an RO filter membrane, it first goes through one or more pre-filters -- typically, a sediment and a carbon block filter.

When an RO system filters water, it lowers the TDS (Total Dissolved Solid) levels. For example, my Arizona water has these TDS levels:

724 ppm - "Fresh" water (no filtering)
697 ppm - RO waste water (brine)
24 ppm - RO treated water (the stuff you drink)

Since I plumb my RO waste water back into my water tank, the tank would eventually reach a point where the RO filter wouldn't work anymore without flushing new water into the tank.

However, if you're concerned about RO waste water fouling your water tank, just put a diverter on the waste water line: one setting to water tank, one setting to the ground or another holding tank.

I've been running an under-the-sink RO unit for several years. While I don't boondock, the system works great. When not connected to an external water source, my RV's water pump forces water from the water tank through the RO membrane.


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Bumpyroad

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Posted: 10/01/20 05:59am Link  |  Quote  |  Print  |  Notify Moderator

TechWriter wrote:

The main drawback of RO systems is waste water. An RO filter will "reject" a lot of water. However, I just plumb the RO waste water back into my RV's water tank.


this is feasible perhaps since you are only "treating" a small amount of water at the sink. IIRC the OP wants to treat all water, a much more difficult task.
bumpy

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Posted: 10/01/20 11:45am Link  |  Quote  |  Print  |  Notify Moderator

Bumpyroad wrote:

TechWriter wrote:

The main drawback of RO systems is waste water. An RO filter will "reject" a lot of water. However, I just plumb the RO waste water back into my RV's water tank.


this is feasible perhaps since you are only "treating" a small amount of water at the sink. IIRC the OP wants to treat all water, a much more difficult task.
bumpy


I addressed that . . .

TechWriter wrote:


The system I and other RVers have are under-the-sink RO units for drinking water. I've only heard from a few RVers who have "whole RV" RO systems in which ALL water going into the RV passes through an RO system. The latter is wasteful, slowwwwwwwwwww, and hardly suited to RVing, much less boondocking.


way2roll

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Posted: 10/01/20 12:10pm Link  |  Quote  |  Print  |  Notify Moderator

TechWriter wrote:





I've been running an under-the-sink RO unit for several years. While I don't boondock, the system works great. When not connected to an external water source, my RV's water pump forces water from the water tank through the RO membrane.


Which system did you go with for your RV? I usually install WATTS type systems - 7 stage, but I really don't need anything that big in our FW.

ToastHater

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Posted: 10/01/20 02:31pm Link  |  Quote  |  Print  |  Notify Moderator

What I'm getting so far is that, filtering ALL of the incoming water would be unnecessary and using an RO system to recycle water for drinking is possible (given the required power to run a pump when needed).

I'm planning on having a substantial solar system (900 Ah Battery Bank, 4000 W Inverter), so power isn't too much of a concern. Just looking at all the steps I can take, no matter how outrageous, to reduce my footprint and recycle as much as possible and increase the time I can boondock. While also keeping things compact within the RV.

I figured the pump would only need to run when refilling the freshwater tank and recycling the gray tank. Then I'd have clean freshwater on tap at all times, instead of running the pump to get fresh water. While also keeping the system clean. When boondocking, you never know how clean the water source is. Do you really want to clean dishes or yourself with that? (I guess that can be mitigated by soaps and cleaners, but still)

Bumpyroad

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Posted: 10/01/20 04:13pm Link  |  Quote  |  Print  |  Notify Moderator

ToastHater wrote:

What I'm getting so far is that, filtering ALL of the incoming water would be unnecessary and using an RO system to recycle water for drinking is possible (given the required power to run a pump when needed).

I'm planning on having a substantial solar system (900 Ah Battery Bank, 4000 W Inverter), so power isn't too much of a concern. Just looking at all the steps I can take, no matter how outrageous, to reduce my footprint and recycle as much as possible and increase the time I can boondock. While also keeping things compact within the RV.

I figured the pump would only need to run when refilling the freshwater tank and recycling the gray tank. Then I'd have clean freshwater on tap at all times, instead of running the pump to get fresh water. While also keeping the system clean. When boondocking, you never know how clean the water source is. Do you really want to clean dishes or yourself with that? (I guess that can be mitigated by soaps and cleaners, but still)


seems to me that you will need and aren't providing for two water tanks, one potable,one not.
bumpy

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