[NWH]

What`s the difference in waste,i`ve heard people say that the waste from the 40x40 is far less than the merlin,i`ve also heard others say that waste from the merlin is the same as the 40x40.Does anyone have the facts on waste as far as these 2 RO`s are concerned,you hear lots of different stories.I`ve read the info on both but does anyone have experience first hand.Cheers.

[Pj]

Ok, without all the technical spec from experience:

I have used a 4040 for 2 years
Mains pressure for 1st year 25psi
TDS in = 390.  TDS out 18
After 1 year like that poor 4040 is being tested!

I added a booster pump:

Mains pressure for 2nd year average 60psi
TDS in = 390.  TDS out has recently dropped to 50.
Time to change membrane....ouch!

What you want to know is waste/conversion?
I use an inline TDS meter to get optimum exchange.
An average was/is about 75% waste to 25% Pure
That converts to about 200-250litres per hour Pure

But I have used up my membrane in 2 years.

Any questions?

[SherwoodCleaningSe]

I have a 4040 going for 8 months now. I have a booster pump and also recycle a percentage of the waste.

Inlet is 400ppm  Outlet is 3ppm or lower.  For every 1 liter pure I waste about .75 of a liter.  I can fill my 1000L tank in 5 hours.

Pj why don't you invest in a water softener to make the membrane last longer.

Simon.

[NWH]

Thing is you here people say that a 40x40 only rejects 25% and the rest goes in the tank,i think not more like the other way round.

[brightnclean]

You CAN run a 4040 at 20% waste but you will ruin it quickly.

In anything like hard water areas a softener is almost a must as well. You should nicely be able to run a 4040 at 1 to 1 waste to pure in a medium water area or a hard water one with a softener first. Regular flushing helps as well.

Te Merlin is in my opinion really only good in soft to medium water areas but the waste is gonna be at least 3 to 1. More like 5 to 1. In hard water areas you really need a softener again.

Given the choice I would go for a 40 inch set up any day.

[Pj]

I have a 4040 going for 8 months now. I have a booster pump and also recycle a percentage of the waste.

Inlet is 400ppm  Outlet is 3ppm or lower.  For every 1 liter pure I waste about .75 of a liter.  I can fill my 1000L tank in 5 hours.

Pj why don't you invest in a water softener to make the membrane last longer.

Simon.

Yes, a water softener might make a difference with a new membrane.  I just have to decide if that is the way I want to go.
New membrane approx £230.  Water softener approx £250.
£500 hmmm!
Nice soft towels and underwear?