[SeanK]

Colin my water is around the 240 mark and my 4040 got it down to 2ppm for the first three years.
Its still at 16ppm after 6 years,
You should be getting yours lower than 25.

[colin bird]

I use a4040 ro tap tds 270 good mains pressure,after ro before di tds reading normally  25 even when ro is new.
I've noticed yesterday tds after ro 32 ,so  I'm assuming ro is on the way out.
In 6 years of wfd my 4040 ro only seem to last approx 18 months,even with regular flushing
I wouldn't be happy with rising tds after 8 months.
Im also looking for ideas in prolonging ro life
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When flushing make sure all the water is running to waste if not then its not a proper flush, if
needs be reduce the water pressure when flushing.
Never let your waters pure to waste ratio go above 50/50
At the end of the days water production slowly loosen of the valve so that the water runs to waste
for 30 seconds or so.
At the start of water production let the water run to waste for a few minutes and then slowly tighten it up
to where its making pure.
Shock will shorten the life of your R.O. ( water hitting the membranes to quick and to hard ) especially if they
have dried a little, that's why I would recommend the above.
I find putting the water through the R.O. straight into the tank and then putting it through a D.I. as and when its needed
a less problematic way to work.
The main reason is there no pressure on the filtered water flowing from the R.O. as it doesn't have to be forced through
the D.I. which is usually on the floor and then back up into the top of the tank.
I'm not sure how much pre filter changing helps maintain the lifespan of the R.O. I don't change mine that often
(every 4 months when membrane was new and for the last 3 years once a year) my R.O. is over 6 years old by the way.
I actually connected the tap water the wrong way round so fully chlorinated water went through the R.O. for about
an hour with out damaging the membrane that was 4 years ago.

thanks for that will try on Sunday when filling,I spoke to pure freedom today they said life expectancy 1-3 years depending on amount of water processed,but I feel for £200 I should get a longer life out of the ro,I process about 2000 litres of pure a week,the other thing I noticed when valve is fully open I get approx 65-35 the higher being waste .i can't get 50-50 ratio as you suggest,will talk to them on monday