pumping water through RO/DI?
 

so what im trying to do is pump water from a barrel into my RO/DI instead of having it come from the house pluming..... this way i can put the waste water from the RO/DI back into the barrel and get 100% efficiency.

I tried hooking this up with a 1900GPH pump and it wasnt enough pressure to push through.... i get water coming out of the waste line but no good water.

any idea how big of a pump i'd need to get this going?

I think the booster pumps for ro units would work. My concern is the TDS in the barrel would elevate would it not? Because a membrane only removes a certain % of TDS then wouldn't your DI get hit harder everytime you ran the unit?

Bingo mate, you hit the nail on the head.

If the OP is doing this to be cost effective I do not think it will pan out over the long term when you look at the cost of replacing the DI resin more often.

You can always save the waste water to the barrel and pump it into the washing machine. It's an alternative ;)

Exactly =) I've got 400 gallons of tank-testing-water destined for the washer myself starting in a few days.

thanks for the reply guys.