wayneb Posted February 5, 2010 Share Posted February 5, 2010 Would like to get some opinions here concerning usage of the "gray" or waste water from an RO/DI system. I would like to use the waste water to top off my various koi/lily ponds. I was thinking of adding another sediment filter to the waste water supply before running it into a holding tank. I pm'd BillB (as pres of APS) for his opinion and he thought that it might be okay as long as the amount is less then 5% of total pond quanity which it would be. He also thought it would be okay to check with other members too for their inputs. I read thru past posts but this specific use of the water wasn't address. As always thanks for you inputs. wayneb PS: Andrew anyway to add "and", "or" to the search option? Quote Link to comment Share on other sites More sharing options...
Zarathustra2 Posted February 5, 2010 Share Posted February 5, 2010 Would you use bad quality tap water to top off your koi pond? Thats esentially what you would be using. Quote Link to comment Share on other sites More sharing options...
Entropy Posted February 5, 2010 Share Posted February 5, 2010 Do you normally top off your ponds with water straight from the tap? If so the RO/DI waste water is not going to make a difference IMO. How much water are you talking about by the way? Ro/DI waste water is really not much worse that the input water in the grand scheme of things. Most RO/DO units have a 5 to 1 rejection rate (or similar) so 5 gallons of RO/DI waste water has the same impurities as 6 gallons of tap water. Then again my 700 gallon pond is green like Kermit the frog right now, so I may not be the best source for advice. Quote Link to comment Share on other sites More sharing options...
wayneb Posted February 5, 2010 Author Share Posted February 5, 2010 Since I set up the ponds quite a few years ago, have always relied on the outside hose to top up/replace water plus what ever rainfall we get. Have not had any ill effects yet as both koi and water plants do fine. However, whenever I did do a "re-do" or complete cleanout of a pond, I removed all fish and plants and transfered them to one of the other ponds (note: have 4- smallest being about 300 gal and the largest about 1500+ gal). Refilled from the hose and usually waited a couple of weeks and then transferred fish and plants back. Our local water supply (Aqua Water) has a high mineral content so am figuring that re-filtered waste water from the RO/DI has to be better or at least not any worse plus the fact it is being put to good use and saving me money. wayneb Quote Link to comment Share on other sites More sharing options...
Jimbo Posted February 5, 2010 Share Posted February 5, 2010 Ro/DI waste water is really not much worse that the input water in the grand scheme of things. Most RO/DO units have a 5 to 1 rejection rate (or similar) so 5 gallons of RO/DI waste water has the same impurities as 6 gallons of tap water. Hmmm. I have to respectfully disagree (based on speculation, not fact) with the statement that the waste water has the impurities of 6 gallons (using your reference). Since the water path through the RO/DI system goes tap > pre-filter > carbon block > RO membrane > DI with the waste coming directly after the first 2 filters (or one, depending on the filter setup). So, I would argue (perhaps incorrectly) that the water would still be significantly better that the source water, with the added benefit of having chlorine removed by the carbon block (again, if configured in the RO/DI system). I'd be happy to hook up a TDI meter to the waste port on mine and to the source to see what the difference is. Now, that being said, the concentration of the minerals in the waste may be different from the source. This depends on the make-up of the source and what can be filtered due to size in the pre-filters. Like, there may be a concentration of heavy metals that make it through the sediment block and carbon block (this is speculation, no example here) that would normally be removed by the RO membrane. This would end up in the waste. Again, this is how I believe it SHOULD function, but I am just speculating. Jim Quote Link to comment Share on other sites More sharing options...
+Daniel Posted February 5, 2010 Share Posted February 5, 2010 Hmmm. I have to respectfully disagree (based on speculation, not fact) with the statement that the waste water has the impurities of 6 gallons (using your reference). Since the water path through the RO/DI system goes tap > pre-filter > carbon block > RO membrane > DI with the waste coming directly after the first 2 filters (or one, depending on the filter setup). So, I would argue (perhaps incorrectly) that the water would still be significantly better that the source water, with the added benefit of having chlorine removed by the carbon block (again, if configured in the RO/DI system). I'd be happy to hook up a TDI meter to the waste port on mine and to the source to see what the difference is. Now, that being said, the concentration of the minerals in the waste may be different from the source. This depends on the make-up of the source and what can be filtered due to size in the pre-filters. Like, there may be a concentration of heavy metals that make it through the sediment block and carbon block (this is speculation, no example here) that would normally be removed by the RO membrane. This would end up in the waste. Again, this is how I believe it SHOULD function, but I am just speculating. Jim I believe you are correct. Quote Link to comment Share on other sites More sharing options...
Jimbo Posted February 5, 2010 Share Posted February 5, 2010 I believe you are correct. pffft...Tell my wife Quote Link to comment Share on other sites More sharing options...
Derek Posted February 5, 2010 Share Posted February 5, 2010 I use it to water my yard. Quote Link to comment Share on other sites More sharing options...
muddybluewater Posted February 6, 2010 Share Posted February 6, 2010 I also agree with Jimbo, my waste water has gone through 3 stages of filtration before it is waste. Plus my water softener. Quote Link to comment Share on other sites More sharing options...
Entropy Posted February 6, 2010 Share Posted February 6, 2010 (edited) Hmmm. I have to respectfully disagree (based on speculation, not fact) with the statement that the waste water has the impurities of 6 gallons (using your reference). Since the water path through the RO/DI system goes tap > pre-filter > carbon block > RO membrane > DI with the waste coming directly after the first 2 filters. Jim Good point. I was thinking of the input at the membrane an honestly didn't factor in the prefilters. Mine is three stage (no DI) so I should have thought of that. Anyway my point was the waste water is going to be no worse than the tap water for a pond application. Anything the prefilters do not catch and is rejected by the membrane whould be in the tap water to begin with and the levels would be no more then 15-20% extra per gallon. I suppose over time that could add up, but it would not be much different than the effects of evaporation (losing water, leaving behind solids). For what it is worth my waste water goes into the lawn. I haven't had to top off my pond since I built it four months ago. Mother nature has been taking care of it. Edited February 6, 2010 by Entropy Quote Link to comment Share on other sites More sharing options...
offroadodge Posted February 6, 2010 Share Posted February 6, 2010 use it to water yard, plants, put it in the laundry and wash clothes with it, all of those are good to use it for. Quote Link to comment Share on other sites More sharing options...
wayneb Posted February 6, 2010 Author Share Posted February 6, 2010 Thanks to all, Will give it a go and see how it works. wayneb Quote Link to comment Share on other sites More sharing options...
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