I have a question regarding RO filters to people who knows how reverse osmosis filter systems work.
RO filter makes pure water and waste water. Mine is about 1 to 3 in favor of waste water. What if I re-filter the waste water to save water this way?
Do you see a reason why it's a bad idea?
Does it do anything bad to the RO system?
I've tried once and I got the waste water purified without a problem.
Where's the catch? Please, someone explain.
There's no problem with doing that at all other than one thing: The plumbing it takes to do it cost far more than the water does.
What you would have to do is capture the waste water, then run it back through the RO filter under pressure. That, in and of itself, requires two different systems.
You can't simply plumb the waste line back into the intake line because you'd get a pressure build up on the waste line that would bring all filtration to a screeching halt.
The only way to really do it would be to have a large reservoir to capture the waste water in, then incorporate a high pressure pump and plumbing to pump it back through the filter again after the main water source was shut off.
Most RO units require at least 45 psi. The pump required to do that is going to cost you around 600 dollars.
The water is far, far cheaper than that.
If conservation is your goal, however, you can always capture waste water for general watering of plants. There's nothing at all wrong with it. Waste water is actually an oxymoron in the case of RO as it's just the water that couldn't make it through the membrane due to volume and back pressure.
Think of it this way: You turn on your kitchen faucet and start to fill a glass with water. The glass gets full. The water then starts running over the edge of the glass. That's waste water in RO. Same thing.
