I have 3 stage water purifier installed at my home which first filters the water, performs reverse osmosis and then treats it with UV-C rays. The water that is released at stage 2 (RO) is usually drained-off. Can this water be used for gardening purposes? Or, better still, can it be collected and somehow passed through the purifier to make it potable?

These questions are related but for another equipment:

  1. Can furnace condensate water be used for houseplants?
  2. Can you drink condensation water from air-con after treating it?
  • What is the source of the water? (I postulate it should be OK, however it will have a slightly higher percentage of "contaminants" (it would likely have 1/20'th to 1/5th more contaminants per litre then if the to filter was not present). I expect this would be unlikely to be an issue.
    – davidgo
    Jan 11, 2021 at 9:17
  • the source of the water is the government managed municipality water supply system; although I have to admit, the water quality index may be way different in most Asian countries than in European/American countries. I currently do not know/have means to measure the quality.
    – anurag
    Jan 11, 2021 at 9:33
  • I suggest reading what the RO process does. Jan 11, 2021 at 19:08

1 Answer 1


I collect water in a bucket using extension feeder pipe as shown in figure. enter image description here

I reuse the water released from system for daily household cleaning purpose. I checked the TDS value at all stages and it is as following:

Source (Tap Water from government): 800-850 ppm Filtered water (RO+UV): 120-130 ppm Released water (stored in bucket): 1000-1100 ppm

Released water is good for flower plants but not for vegetable plants. But there is also need to check mineral content of released water to confirm gardening uses.


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