RO/DI Unit Producing too much water

[InLimbo87]

My RO/DI unit is producing too much water. It is a 75 GPD unit and instead of dripping the "clean water" (as usual) it has been streaming much faster. I just replaced the RO membrane and DI resin, and the other filters were replaced just months ago.

 

What could be causing this? I had a cheap-o TDS meter, but it broke on me recently so I have no way of testing the TDS.

 

Thanks in advance for any help.

[clownfish14]

make sure you have the flow restrictor on the side with the clean water and not on the waste water side. when i first set mine up the waste water was just being pushed through to the clean water. hope that makes sense.

[InLimbo87]

On my unit, the flow restrictor is kept along the waste line. Here's the diagram: http://www.thefilterguys.biz/five_stage_ro-di_system.htm.

 

Does it take time to "break-in" new RO membranes? I've ran it now for an hour or so and it appears to be doing more like 150 gpd at the moment.

[InLimbo87]

Any other ideas?

[cuog]

Did it start producing more water before or after you replaced the membranes? Is it possible that it had just gradually slowed over time so the true 75gpd seems very fast to you? If you're unsure of your assessment, you may just want to time how long it takes to fill up a 1gallon bucket and do the math to see what rate its actually producing water.

[AZDesertRat]

Your membrane is not seated tightly in the housing. Unscrew the cap and push it in further.

Note in the attached article how the nipple should just barely be sticking out, otherwise the water bypasses the membrane.

http://www.purewatersystems.com/memb_replacement.php

[InLimbo87]

Did it start producing more water before or after you replaced the membranes? Is it possible that it had just gradually slowed over time so the true 75gpd seems very fast to you? If you're unsure of your assessment, you may just want to time how long it takes to fill up a 1gallon bucket and do the math to see what rate its actually producing water.

 

It was doing it before the replacement of the RO membrane, and now it is still doing it after replacement. I have filled up multiple 1 gallon jugs and it looks like I'm at about 140-150 GPD as 1 gallon is filling up in 10-11 minutes.

 

Your membrane is not seated tightly in the housing. Unscrew the cap and push it in further.

Note in the attached article how the nipple should just barely be sticking out, otherwise the water bypasses the membrane.

http://www.purewatersystems.com/memb_replacement.php

 

I was worried about this, and have pulled it out and reseated it several times. The end of it sits flush with the canister at the moment, and I have a feeling it has a good seal as I have to really pull with pliers to remove.

[AZDesertRat]

You probably have a cracked housing then if it started before the new membrane installation. Often hairline cracks are not visible but open up under pressure, pretty common and not too expensive to replace a housing. The broken housing will also give you higher TDS which is why you need the TDS meter.

 

To do an accurate troubleshooting you will need an inline pressure gauge, thermometer, TDS meter, measuring cup and watch or clock. You need to know your pressure at the membrane, water temperature, waste ratio and TDS of the tap, RO only and RO/DI to do an exact diagnostic. These item will tell you exactly where your problem lies but my money is on the membrane housing at this point.