[wayne m]

I’ve now set up my static system with a booster pump as I’ve said before in a previous post my tap TDS is 292 ish and have set my system up at 2-1 waste ratio is this about right or would you recommend more waste than this? Thanks

[p1w1]

If this is a 40/40 membrane I would say you want around  60/40 with that tds, you would not be overworking the membrane with that and it should last you a while. If water use is not an issue (not on a meter or anything) i would even consider  70/30.

[wayne m]

I’m on a metre and still have to install a sub metre as I’ve got a separate tap in the garage for the static setup and called the water board for a reduced non return to sewer rate off the water bill and they have agreed.

[wayne m]

I’ve been using a 2litre bottle and a 1 litre bottle and just been doing it so they both fill at the same time

[p1w1]

So your currently running 50/50 which can be fine. Basically the lower the waste ratio the quicker the membrane will get used but also the less water needed to produce your pure water. From my experience, I've found 60/40 the best overall for both water usage and membrane longevity. But just depends on how much water you need a day and how quickly you need it to be made.
If it was me with a TDS of around 300, I would run at 60/40, that's at using 500lt a day and letting the R/O fill up during the day while I'm at work.

[wayne m]

Sorry it’s a 2 litre bottle and a 1 litre bottle but both filling up to the top at the same time so 2 litres of waste to 1 litre of pure. I use about 400 -500 litres a day and have it so it’s filling up when the water level drops in the static tank. Thanks for your replies

[Stoots]

I run mine 1:1 yours is 2 :1 ratio.

I would say on a meter 1:1 is probably more economical.

If you dont have a meter waste as much as you want.

[Spruce]

Sorry it’s a 2 litre bottle and a 1 litre bottle but both filling up to the top at the same time so 2 litres of waste to 1 litre of pure. I use about 4 litres a day and have it so it’s filling up when the water level drops in the static tank. Thanks for your replies

Your r/o will tell you where its best set at.  As an earlier poster has said, I would slowly reduce your waste down a bit and take pure readings as you go.  You will reach the exact point where your r/o will start to perform less efficiently.

My r/o works best at about 55 waste to 45 pure.  If I open the waste gate slightly I will increase the waste to pure ratio to 60/40. This doesn't effect the output quality of my pure but I use more water. If I open the waste gate a little more to 70 waste 30 pure the tds of the pure rises as the pressure across the membrane producing pure drops.

If I go the other way and restrict the waste to pure to 50/50 then over an extended period the tds of my pure will rise 1ppm. If I go to 40 waste and 60 pure then the tds of the pure rises substantially.

All this is at 50psi water pressure, an HF5 membrane and no booster pump. 

[Simon Trapani]

I agree with Spruce. Adjust your waste valve, preferably a gate valve for better accuracy & just find your ‘sweet spot’.

[wayne m]

Thanks for the replies, when I first set it up at 2.1 I tested the water coming out of the ro and it was running at 8. Before I had the booster pump which is set at 80psi from the supplier it was coming out at 17 and I’m using a hf5. I’ll have another go this weekend.

[andyM]

50/50 ratio if on a water meter.
Otherwise you're just chucking water down the drain unnecessarily.
And it will cost you more in water than it will to replace the membrane.