[colin bird]

does any put the waste water from the ro into a tank and put it through the system a second time to purify ? by using a booster pump
can it be done ?
if yes what are pros and cons ?

[dave0123]

You can re-circulate some waste anyway by putting a t- connector on your waste pipe and re-circulate it

[Jonny 87]

Have you checked the TDS of your waste water?

[colin bird]

Have you checked the TDS of your waste water?

no ! but thats a good point

[colin bird]

You can re-circulate some waste anyway by putting a t- connector on your waste pipe and re-circulate it

thanks for your reply,apologies but im not getting where to fit the t connector

[matthewprice]

Local firm uses pure to clean circuit boards before soldering , they tried that and found they had a build up of something in the water that caused them problems with there to
And with what was being dumped /so started using water once

[Jonny 87]

Have you checked the TDS of your waste water?

no ! but thats a good point

I reckon it will be super high TDS. Membranes might really struggle after a while.

[colin bird]

Have you checked the TDS of your waste water?

tap 175 waste from ro 160 dont know if that makes sense but have taken two readings

[Jonny 87]

Wow, didn't expect that atall! Thought it would be double your tap TDS.

[James Bulton]

Why would you put reject water through a RO that has just rejected it. If you want ro reduce your waste water add another ro membrane to you existing ro membrane in tandem and another if you wish.But this last membrane will struggle and not last long . Its not really waster water its flushing water and cleaning your membrane all the time so its very important to have waste/flushing water.

[Don Kee]

Why would you put reject water through a RO that has just rejected it. If you want ro reduce your waste water add another ro membrane to you existing ro membrane in tandem and another if you wish.But this last membrane will struggle and not last long . Its not really waster water its flushing water and cleaning your membrane all the time so its very important to have waste/flushing water.

Your advice is dont recirculate waste water, and put membranes in tandem...?
Isn't that telling him to do what you told him not to and he'd be fitting the next membrane to the previous membranes waste....

If you have a  40/40 adjust the wate/pure ratio or if you have a normal r.o i dont think there is too much you can do about the waste. Adding a booster pump or adding membranes in parallel will make pure quicker, therefore making less waste.  

To be fair to smithie, hes right in regards to flushing. By recirculating the waste, you'd just be putting back in what has just been cleaned off your membranes...

[James Bulton]

I don`t recall him saying he had a 4040. If you give half information you get half the truth..

[David stewart]

Keep it for spraying on messers windows 

[Simon Mess]

I remember reading a thread about this on another forum. I had thought about the same thing, as i hate all that water running down the drain. I just assumed the waste water was what the r/o couldnt handle, that is, it would still be just tapwater. Even though it was explained that the waste was much more concentrated, and likely to wear out filters and membranes quicker, i was a bit skeptical. But after i got myself an r/o system, i took a reading from the waste, the tds was nearly double what came out the tap. Lesson learned!.

[colin bird]

I don`t recall him saying he had a 4040. If you give half information you get half the truth..

yes I have a 4040 ro is that more beneficial ?

[seanrimmer]

Its a question that never goes away; here's my take. The waste water is basically concentrated water; the membrane rejects the majority of dissolved solids & this is usually sent to drain. The purity & production rate depends on the quality of the water to start with (TDS reading), the pressure the water is boosted to & available flow rate. By decreasing the rejection rate, you produce more RO quality water, but increase the TDS loading of dissolved solids on to he membrane surfaces/pores. Therefore, if you want to produce as much RO water, with as little waste water as possible, your membrane life expectancy will shorten. You have to make a commercial decision; if I was on a water meter, I'd probably hammer the cheapest membranes available & build in their replacement cost against the cost of water down the drain. If not on a water meter, I'd increase the number of membranes I'm using & run them gently, though mindful if you run at reduced pressures, you may well use more demin resin, as the quality goes down with pressure on the membranes.

[Avo]

Dose it really cost a lot being on water meter then for example filling a 500 litre would cost what exactly??

[LBWCS]

Dose it really cost a lot being on water meter then for example filling a 500 litre would cost what exactly??

yes over time

[James Bulton]

Don kee Take a look at the Ionics parts per billion set up its five membranes in tandem. Whether its makes sense is another matter.It has been done. 

[Don Kee]

Don kee Take a look at the Ionics parts per billion set up its five membranes in tandem. Whether its makes sense is another matter.It has been done. 

Fair point, to me it makes no sense though...
Waste water tds is higher, so you would batter the membranes!
Having them in parallel means the input tds is the same on all memranes (40/40 or normal) and so get even wear...
I might be wrong though i guess