Reverse Osmosis

[Sorcerers Apprentice]

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[Beerbuddha]

Don't forget cheap TDS meter to check when filters are goosed. Saves changing them earlier than needed.
My neighbour changed the filters in his few weeks ago and I checked them his dissolved solids through the roof must have mad a bags of filter install. Again without tds you cant tell.

[Sorcerers Apprentice]

Cheers Declan

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I should have picked one up with the unit.

[auralabuse]

Where can ya get hold of a TDs?

[molc]

Ditto, need to check that myself! I've installed in the kitchen as well and it takes about 7 hours to fill 25L. I just filled the old cider drums and going to have 2 always filled and waiting.

[Sorcerers Apprentice]

I hooked it up this evening and there was a substantial flow to drain at the start. I'll get the missing seal and report back

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[Will_D]

The NCBers bought two of the cheap 3 stage systems (like £55 stg)

This is what I posted:

I have a fairly healthy mains pressure (say 2 bar but must check)

Quick test shows the waste to RO ratio is better than 2 to one. Is actually 1.7 to 1 at present.

Flow rate is 150 mL per minute or 9 litre per hour.

I imagine over time these figure will change.

[Will_D]

What I don't understand in the whole RO process is:

"Why is there waste water?"

A RO membrane is a molecular/ion sized filter. It is just like a filter paper!

You don't get waste from a filter paper!

You are in theory just pumping water into a very very fine, very large surface area, filter. Pure water comes out, the ions don't.

It should be possible to back flush the filter with a "small" quantity of RO water to physically remove the ions. Like what you do with an ion exchange water softner.

(Like washing the sieve in the kitchen)