Depends, where are those other two gallons going? If it is going down the drain, than the answer would be a general no, but do we blame that on the unit or just how we install them normally?
As a side note - no argument on the systems being great, producing clean water & recomending them when water quaity is an issue or an individual requires might have health issues
Thanks for your input.
Unfortunately, yes, the 2 gallons do go down the drain which results in energy consumption to pump it back though the treatment facility and back again. And, yes, we blame it on the unit, that's just the normal average of properly functioning units.(nothing to do with installation). It's a gray area. Perhaps it's just a fact that people choosing high quality healthy water purification systems cause some extra energy consumption (which causes carbon emissions). Maybe someday they will make it a gallon/in and gallon/out ratio.
The waste water could not be recirculated back to the input of the purification system, but it could be used for other purposes. The 2 gallons of waste water contains the ions that were originally in the one gallon of de-ionized water.
Is this RODI system used only for drinking water, or for all household water?
Our household uses a filter mounted under the kitchen sink for drinking/cooking water, which we draw from a dedicated tap. The tap water supplied by our local water district contains no alarming levels of toxins such as lead, and since we replaced most of the old iron pipes in the house, rust has not been a problem anymore. Filtration should be fairly low energy cost, given that the filter is only replaced annually, and uses no excess water. What level of purification is needed depends on the local water supply.
My RO system is awesome and I super happy to be enjoying tasteless (Was poor tasting) water, and not purchasing disposable plastic bottles. The RO system I have does not waste any water, yup ZERO WASTE. Instead it pumps the heavier concentrated water into the hot water pipe. The system I purchased from ebay came with the pump and pressure switch for systems like wells where they have low pressure. All it took was one phone call to Watts Premier and they set me up with the solenoid needed and the check valve. Installation was easy and only required some valve changes to allow the RO lines on both sides, hot and cold water lines. The drain line into the sink is not used, but since I did mine on a fresh install I never made a hole there. It could be plugged, and they in fact sell a plug, or if you buy the kit it comes with the plug.
There are some requirements. The hot water heater must use a tank, not tankless, and it must be at least 25' from the RO system. For most unless you have a gravity feed heat pump system or a pump mounted on the hot water side, will turn the hot water on and run it for a minute to bring the hot water to the sink for washing dishes. Either way the unused RO water is living a second life. Insulating the hot water pipes and putting a pump inline with the hot water with a switch at each faucet that triggers the pump to run long enough to circulate the hot water, would be very green. Water is going to be a huge environmental issue moving forward. Being able to have hot water as soon as we open the faucet creates much less waste.