[greenavocado]

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]

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]

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]

Most in-home systems sold today drain to waste without any attempt at recovery to keep manufacturing costs low.

[ohthanks]

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.