Back Pressure Preventing Check Valve from Opening?

[Adamantium]

Hi all, not sure if this is the right forum, so please let me know.

I'm working on keeping TDS creep out of my DI resin, so I added a Y valve on my RO outlet, with one output going into DI, and the other hooking into my RO waste line.

There are ball valves on each, so when I start up the unit, I close the line going into the DI, and open the one going to the waste line. The thing is, the pressure coming out of the waste line is way higher than that coming out of the RO membrane. As such, I'm worried about back flow coming back up into the RO membrane.

I was thinking I'd put a check valve in before it hits the waste line, so that only the RO water can escape, but waste water can't get back in. However, I'm worried that the pressure from the waste line will push back on the check valve, preventing it from opening.

I hope that made some kind of sense.

Thanks for any insights you can provide!

 

[TheEngineer]

You’re connecting to the RO waste line before the flow restrictor?

 

[Adamantium]

You’re connecting to the RO waste line before the flow restrictor?

After, but it’s definitely still a stronger flow than comes out of my RO product line.

 

[TheEngineer]

After, but it’s definitely still a stronger flow than comes out of my RO product line.

The RO line output can handle the back pressure, but if I were you I’d just run a separate waste line. Seems like the simplest solution.