Ro Units

[smithrc]

no one has bentioned "waste" yet...

the RO unit connects into the mains water feed... it can produce somewhere near the rated gpd... but they also have a ratio of RO to waste water... again this varies....

when you turn the water supply on the water passes through the different stages of filtration and comes out as very highly filtered "RO" water, however they also have a 2nd output, the minerals and chemicals that the RO filter has removed get washed away out of the "waste" pipe... the ratio of RO to waste is quite low... 5:1 or in my case 8:1.

so if we take a 50gpd unit that actually produces 40gpd. and say it has a 5:1 ratio, when you turn the tap on and the RO starts to come out - you will get more waste coming out that RO aswell.

so to produce 40gals of RO you will also produce 200 gallons of waste water....


its a lot of water to waste really... (ok its only a few £ when you work it out - but if feels wastefull)

So I've plumbed our RO output into the garden watering system - the plants will get the higher nutrients etc in the waste too

 

[SkiFletch]

ts a lot of water to waste really...

While I agree, I'd also like to stipulate that it really depends on your environment. For someone like Fishlette or Mr Miagi living in Australia where water is scarce, it's very wasteful. However for those of you in the UK and many of us here in the US, it's not at all. Consider this:

Your tapwater comes from a nearby river, lake, or aquifer. You make 10 gallons of RO and "waste" 40 which goes down your drain to your sewer and then to your water treatment plant. There it's filtered and treated and in many cases released back to the same water table from which it was drawn. So you've really only taken 10 gallons.

Obviously though if your water comes from some deep non-replenishable well, desert rainwater, or some other extreme environment, then yes an RO unit is quite wasteful.

Hope that rambling made sense.

Orange Shark: You can determine how fast your unit is working by filling a bucket or container of known volume, noting how much time it took to fill that up and there you have the flowrate. Musho is probably taking a 5 gallon bucket and timing how long it takes to fill... The only other "testing" of RO water is with a TDS meter to determine how well it's working as I mentioned above

 

[Musho3210]

there are ways to not waste as much water by getting a duo RO unit, this is where tap water is purified, then the waste water from the tap water is then purified by another RO membrane. The problem with these is that they need at least 60 psi of pressure to work, and even with that they dont produce much. As ski said before most taps have 30-50 psi. So unless you have a high psi out of your tap, you may need to buy a booster pump for a duo RO unit to work well.

 

[orange shark]

ohhhhhh, so the water doesn't lose its quality like said in the first post?

 

[WayneVT08]

Yeah but as Ski said, water is scarce some places, like where I'm at, and we've only had about .06 inches of rain in AUGUST!

 

[Musho3210]

ohhhhhh, so the water doesn't lose its quality like said in the first post?

distilled and deionization doesnt waste as much water, those are other alternatives.

 

[orange shark]

the first post said its how much the ro unit can produce without losing quality and you said it creates 5 gallons every 6 hours so i was wondering how you tested the quality of your water (if that makes sense)

 

[idlefingers]

the first post said its how much the ro unit can produce without losing quality and you said it creates 5 gallons every 6 hours so i was wondering how you tested the quality of your water (if that makes sense)

You use a TDS (total dissolved solids) meter. You can get ones which you can dip into a sample of water or ones which connect to the in/out RO pipes and constantly read it.

 

[SkiFletch]

With a TDS meter I'm sure. TDS - Total Dissolve Soids. RO membranes that either need flushing or replacing will have their RO discharge TDS increase significantly. Lets you know when there's a problem

 

[Musho3210]

Tap - 140-160
RO water - 7-9
DI water 0-1

 

[xxBarneyxx]

Think everything useful has been covered. Did just want to add a comment on the waste water in the UK, even in a country where it seems to rain for at least 10 months out of twelve we still have hosepipe bans Doesn't add anything useful to the conversation but I thought the non-UK residents might find it amusing

 

[Musho3210]

i just feel lucky that i live next to one of the biggest freshwater lakes in the world and i stop feeling bad since all the water i use comes from there and when im done with that water, it goes back.

 

[SkiFletch]

i just feel lucky that i live next to one of the biggest freshwater lakes in the world and i stop feeling bad since all the water i use comes from there and when im done with that water, it goes back.

Lol, where do you live Musho? Same here, all off Lake Erie, part of the great lakes which in total do makeup the largest freshwater resevior on the planet

 

[Musho3210]

chicago (well a suburb just north of chicago)