View Full Version : Low Output

08/29/2010, 01:12 PM
I think it might be time to change my membrane. Have a 5 gallon jug on the 75 GPD RO/DI system and total time elapsed is 2.5 hrs and the jug is only slightly less than 1/2 full.

It seems just dripping and the majority of the water is going down the waste line. Is it possible the flow restrictor needs replaced and not the membrane? Please let me know what you guys think so I can get the parts on order.

08/29/2010, 01:42 PM
Normally from a 75 GPD membrane we expect about 2 gallons per hour and with warmer tap water like you have the production is even higher. You could have a failing membrane or clogged filter causing lower pressure. We generally expect 2-3 years from a membrane. Do you have any pressure readings or RO tds readings?


08/30/2010, 06:48 PM
Yes, house pressure is 60 psi typically from the city water supply. TDS before DI just now was ~130 and ~43 after, after a couple of minutes of turning on the system the before TDS dropped to 44 and the pressure after the 3 filters before the membrane is 10 psi.

I will do another timed test tomorrow to see what it is doing.

08/30/2010, 07:53 PM
Your pressure after filters at 10 psi tells me you have clogged filters and you after RO reading tells me it may have clogged the membrane also, or you membrane is going bad. You need to resolve the filter issue first. You need new filters but first try removing the third stage carbon filter and see if pressure returns to 60. You must have one carbon stage in the system at all times. If the pressure returns you need to remove the flow restrictor from you waste line and flush for 20 minutes and see if the tds drops once the restrictor is put back on. This is a guess but filter clogs due to carbon breakdown are very common with chloramine disinfectant.


08/31/2010, 07:18 PM
I let the system flush for a couple of hours, then tested again before reading your post and got 8 cups in 40 minutes.

I will remove the carbon filter tomorrow and see what the water pressure goes to.

"This is a guess but filter clogs due to carbon breakdown are very common with chloramine disinfectant."

I haven't made much water with the system, maybe on the order of 18 5 gallon jugs. Is there something I can do to get the filters to last longer?

Will let you know how it goes tomorrow evening.

thanks for the replies

09/02/2010, 08:45 AM
1/2 gallon in 40 minutes isn't good let me know the results of filter check?


09/19/2010, 02:43 PM
My apologies, got slammed at work and travel so had to postpone the test.

I removed the 3rd stage filter today, and the pressure is still less then 10 and tds after DI is around 99.

I am wondering if somehow I might need a new flow restricter, maybe? The water flows freely at the drain side.

This mighe be worth a shot. Let me know what you think, thanks again

09/19/2010, 03:11 PM

With the 3rd stage removed I timed the water fill rate at the drain with the fill line open & closed, both rates are identical at 4 cups in 4 min 32 secs measured at the drain (0.25 gallons in 4.53 minutes = 0.055 gpm). Don't know if that helps any.

Let me know what to do next, thanks

09/19/2010, 10:35 PM
You need new filters and a membrane.


09/20/2010, 05:23 PM
Wow, that is a bummer.

Hopefully this was just a fluke.

Are you sure the membrane is bad as well, this is going to be around (45 dollars for the membrane and $53/41 dollars for the filters) $100.

Is there something I can check to see if I need to replace both the membrane and filters? The DI is about 1/4 brown at the bottom.

Anyways, let me know. After your next reply I will take the recommended action. Thanks

09/20/2010, 10:48 PM
Your low pressure is before you RO so that tells me bad filters or closed off water connection. If you connected with a self piercing saddle valve they can close off, cuased by water chemistry. The low pressure and that 99 tds reading sounds like it has impacted your membrane.

You can order filters and check your water connection but I have a feeling your going to need to replace the membrane also. Please call me if you like and we can talk 218 724-8000


09/21/2010, 05:30 PM
Thanks for all your help, will check the water connection but will take your advice. Will be ordering soon. Thanks again for help in troubleshooting this