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RO has some very easy to maintain, and user install options, which I've done. ( https://www.geappliances.com/ge/water-filtration-systems.htm https://www.geappl

RO has some very easy to maintain, and user install options, which I've done. ( https://www.geappliances.com/ge/water-filtration-systems.htm https://www.geappliances.com/ge/water-filtration-systems.htm ) However RO is not water efficient, in the sense that only a fraction of water run over the RO membrane system is filtered, and otherwise inbound water goes on into the drain. You can hear this happening, and it's documented by GE, for example, as how the systems work. That makes me wonder if there are other systems with the characteristic that a higher % of ingested water ends up filtered as well as RO can.

greenavocado 3y ago
A permeate pump can typically reduce water waste in reverse osmosis systems by up to 80%. In general, permeate pumps can achieve a waste water reduction of around 50% to 80%. This means that for every gallon of purified water produced, only around 20% to 50% is wasted as reject water. This is achieved by utilizing the energy from the brine flow to enhance the pressure applied to the feed water, leading to increased permeate production and reduced reject water volume. Typically, these pumps range from $50 to $200 and they do not use electricity. The elevated pressure allows for more effective filtration and higher water recovery rates. By boosting the pressure, permeate pumps facilitate a greater volume of water passing through the semi-permeable membrane, resulting in increased production of purified water (permeate) and reduced reject water (brine). The heightened pressure helps overcome osmotic pressure and allows for a more thorough extraction of purified water from the feed stream.
- wbl 3y ago
  The domestic RO systems put pressure on the clean water output and don't have recovery systems for brine pressure? What? My only experience with RO systems are on sailboats, where a brine pressure recovery system is the only way to get the power down, and the water trickles into the tank under low pressure from where it is pumped out.
  - jjtheblunt 3y ago
    The linked system above just sends the unfiltered tap water down the drain. I have had two iterations of the GE system and it says so in the manual, for instance. I am not sure about other brands and their systems.
    - greenavocado 3y ago
      Most in-home systems sold today drain to waste without any attempt at recovery to keep manufacturing costs low.
- ohthanks 3y ago
  They don't boost the feed pressure, just isolate the output permeate line from the back pressure of the storage tank. Instead of the membrane output pushing against the increasing pressure of tank as it fills (decreasing output) it produces into a void in pump body which the pump periodically pushes into the tank from spring mechanism wound by the output waste water. They work pretty well to reduce waste but do add complexity to what is already a somewhat complicated device under the sink. They will also create bad TDS creep if used without an auto-shutoff valve installed in the RO.
TaylorAlexander 3y ago
Yeah my dad has an RO system at their house but it goes to a special tap next to the main one that is used only for drinking water, due to the waste associated. Maybe it isn’t needed for hand washing, showers, etc as long as there are good standards at the water distribution facility.
- datascienced 3y ago
  Thats how I use it. In theory the waste could be used for irrigation or mixed into shower water but that requires more plumbing to deal with an external cost (in areas where water is limited).
  - mattmaroon 3y ago
    Well, if you live somewhere with a municipal water supply, the water just gets recycled anyway. I suppose if you’re on septic it’s still going right back into the ground it came from. Drinking water is probably such a small percent of overall water use that wasting even a multiple of it doesn’t amount to much anyway. So filter away! I’ll worry about my r/o waste when people stop diverting rivers to grow almonds in the desert and not a second before.
    - TaylorAlexander 3y ago
      I think the point is that we should not as a general rule recommend people do RO for their entire house. Toilets, showers, and washing machines don’t need RO water and if a lot of people did a whole home RO system we would start to see waste add up.
      - mattmaroon 3y ago
        Oh. Sure. That will always be so cumbersome we don't have to worry about it. That would be a huge RO system. They don't have a lot of throughput so you'd need a big storage tank or a very large set of filters and a pump I'd think. I'm not at all concerned whole home RO will every be common.
r00fus 3y ago
Anyone considered just sending the brine to the yard as gray water?
- jonhohle 3y ago
  Premiere H2O has a system that dumped the water into the hot water line, similar to a hot water loop, but in reverse. There’s a lot of caveats with that arrangement (doesn’t really work with a tankless water heater, for example).
  - r00fus 3y ago
    Wait, they push the waste/brine into the hot water line? Wouldn't that defeat the purpose of filtration? I was thinking more of using it typical gray water usage like watering plants.
    - tacitusarc 3y ago
      I imagine despite the term brine it is still incredibly clean water
    - formerly_proven 3y ago
      > Wait, they push the waste/brine into the hot water line? Wouldn't that defeat the purpose of filtration? Hot water is for external use only.
      - evancox100 3y ago
        ... you’ve never used hot water to fill up, say, a pot of water for cooking?
        TsiCClawOfLight 3y ago
        it's gross. Don't do that.
      - soperj 3y ago
oceanplexian 3y ago
It seems like it would be mostly irrelevant that it’s not efficient? What percentage of residential water goes to drinking water? I think of all water use in aggregate, in many places it’s already 90% is agriculture and 10% residential. And of residential you probably waste more water in a single toilet flush than you drink in an entire day.
schnable 3y ago
I have an RO system, which seemed great until I realized the nicely filtered water runs through plastic tubing before coming out the faucet.

greenavocado 3y ago

A permeate pump can typically reduce water waste in reverse osmosis systems by up to 80%. In general, permeate pumps can achieve a waste water reduction of around 50% to 80%. This means that for every gallon of purified water produced, only around 20% to 50% is wasted as reject water. This is achieved by utilizing the energy from the brine flow to enhance the pressure applied to the feed water, leading to increased permeate production and reduced reject water volume. Typically, these pumps range from $50 to $200 and they do not use electricity. The elevated pressure allows for more effective filtration and higher water recovery rates. By boosting the pressure, permeate pumps facilitate a greater volume of water passing through the semi-permeable membrane, resulting in increased production of purified water (permeate) and reduced reject water (brine). The heightened pressure helps overcome osmotic pressure and allows for a more thorough extraction of purified water from the feed stream.

wbl 3y ago
The domestic RO systems put pressure on the clean water output and don't have recovery systems for brine pressure? What? My only experience with RO systems are on sailboats, where a brine pressure recovery system is the only way to get the power down, and the water trickles into the tank under low pressure from where it is pumped out.
- jjtheblunt 3y ago
  The linked system above just sends the unfiltered tap water down the drain. I have had two iterations of the GE system and it says so in the manual, for instance. I am not sure about other brands and their systems.
  - greenavocado 3y ago
    Most in-home systems sold today drain to waste without any attempt at recovery to keep manufacturing costs low.
ohthanks 3y ago
They don't boost the feed pressure, just isolate the output permeate line from the back pressure of the storage tank. Instead of the membrane output pushing against the increasing pressure of tank as it fills (decreasing output) it produces into a void in pump body which the pump periodically pushes into the tank from spring mechanism wound by the output waste water. They work pretty well to reduce waste but do add complexity to what is already a somewhat complicated device under the sink. They will also create bad TDS creep if used without an auto-shutoff valve installed in the RO.

TaylorAlexander 3y ago

Yeah my dad has an RO system at their house but it goes to a special tap next to the main one that is used only for drinking water, due to the waste associated. Maybe it isn’t needed for hand washing, showers, etc as long as there are good standards at the water distribution facility.

datascienced 3y ago
Thats how I use it. In theory the waste could be used for irrigation or mixed into shower water but that requires more plumbing to deal with an external cost (in areas where water is limited).
- mattmaroon 3y ago
  Well, if you live somewhere with a municipal water supply, the water just gets recycled anyway. I suppose if you’re on septic it’s still going right back into the ground it came from. Drinking water is probably such a small percent of overall water use that wasting even a multiple of it doesn’t amount to much anyway. So filter away! I’ll worry about my r/o waste when people stop diverting rivers to grow almonds in the desert and not a second before.
  - TaylorAlexander 3y ago
    I think the point is that we should not as a general rule recommend people do RO for their entire house. Toilets, showers, and washing machines don’t need RO water and if a lot of people did a whole home RO system we would start to see waste add up.
    - mattmaroon 3y ago
      Oh. Sure. That will always be so cumbersome we don't have to worry about it. That would be a huge RO system. They don't have a lot of throughput so you'd need a big storage tank or a very large set of filters and a pump I'd think. I'm not at all concerned whole home RO will every be common.

r00fus 3y ago

Anyone considered just sending the brine to the yard as gray water?

jonhohle 3y ago
Premiere H2O has a system that dumped the water into the hot water line, similar to a hot water loop, but in reverse. There’s a lot of caveats with that arrangement (doesn’t really work with a tankless water heater, for example).
- r00fus 3y ago
  Wait, they push the waste/brine into the hot water line? Wouldn't that defeat the purpose of filtration? I was thinking more of using it typical gray water usage like watering plants.
  - tacitusarc 3y ago
    I imagine despite the term brine it is still incredibly clean water
  - formerly_proven 3y ago
    > Wait, they push the waste/brine into the hot water line? Wouldn't that defeat the purpose of filtration? Hot water is for external use only.
    - evancox100 3y ago
      ... you’ve never used hot water to fill up, say, a pot of water for cooking?
      - TsiCClawOfLight 3y ago
        it's gross. Don't do that.
    - soperj 3y ago

oceanplexian 3y ago

It seems like it would be mostly irrelevant that it’s not efficient? What percentage of residential water goes to drinking water? I think of all water use in aggregate, in many places it’s already 90% is agriculture and 10% residential. And of residential you probably waste more water in a single toilet flush than you drink in an entire day.

schnable 3y ago

I have an RO system, which seemed great until I realized the nicely filtered water runs through plastic tubing before coming out the faucet.