reverse osmosis drain issue

I have a reverse osmosis home filter system and was wondering if the drain leak ever stops. I'm talking about the membrane waste that goes into the drain. Is it leaking 24/7? (seems like it)

Also, I have a 50GPD membrane and was wondering if it wastes more water than a 25GPD membrane. I'm asking because I bought the higher capacity because it may last longer than the 25GPD since it can handle more GPS.

So here are me questions:
Does the waste line always drips/leaks?

Is the 50GPD better than the 25GPD membrane for a home filter? (price is almost the same).

Is it normal for the system to make noise/vibrate? (the noise occurs for about 1 second and it's random from what I can tell, does it around 2-3 a day)

Thanks for those that can answer my questions!

 

The waste should shut off.
You either have a bad Auto Shutoff Valve (ASOV) or the air charge in your pressure/bladder tank is low or both.

Drain the pressure tank completely and disconnect the 1/4" water line hooked to it. Using a low pressure tire gauge check to see that you have 5-7 psi in the tank. If not use a bicycle pump or small compressor to raise it to 6-7 psi for best performance.

Let the system fill the tank again and check to see if the waste has stopped. If not then you probably need a new ASOV for around $12- $15 for a good one.

As for waste, all membranes are recommended to waste 4:1 regardless of GPD. A 50 GPD or 75 GPD will make water faster than a 25 GPD but if you make 5 gallons or water you will have only wasted 20 gallons with any of the membranes. This is theoretical though and membranes used with pressure tanks actually waste much more as they are fighting the pressure in the tank which increases the waste ratio until it finally shuts off. Systems that have no backpressure such as a RO/DI going into a trash can do not have this problem so the waste stays constant.

If you have a pressure tank I highly recommend using a permeate pump to reduce your waste. The permeate pump uses the stored pressure in the tank to drive a piston pump and aid the membrane so it reduces waste. They will ONLY work if you have a pressure tank though and do nothing without it.

If it were me I would get Spectrapures 90 GPD membrane and matched flow restrictor for around $45 complete. It is a specially treated and tested membrane that will outperform a normal 25, 50 or 75 GPD membrane and fits in most RO systems with the exception of a few like some Watts Premier, Sears and Whirlpool, all of which take a non standard membrane.

 

The ASOV is new, I just replaced because I thought that was the problem too. We use maybe around 3 gallons per day, so we would be wasting 12 gallons of water!?

The pressure tanks seems fine, we get a good stream, plus it's not that old. Though I will find a pressure reader to confirm the PSI.

I honestly can only think of three things that could be causing the issue:
1) The 50GPD membrane is too big
2) The membrane could be installed improperly and water is leaking past the membrane sealer at the side.
3) For my post-filter, I have this (quick connected instead): https://www.wattspremier.com/products.php?product=1{47}4"-Male-Run-tee
In a lot of diagrams I've seen this one: https://www.wattspremier.com/products.php?product=1{47}4"-Tee--Fitting-
Maybe I have the wrong tee connecting the post-filter, membrane, and tank?

I will verify #2, since I can open the housing. What do you think of #1 and #3?

Thanks again for your help.

 

No, no and no.

Do what I have suggested.

Also make sure there is no air trapped in the housings or membrane causing the ASOV to fail to shut off. You may also need a check valve in thecircuit assome ASOVs do not work well without a check valve.
Take a look at the check valve placement in the diagram here.
Notice it is between the RO membrane and the ASOV.
http://www.spectrapure.com/huds/DWS-DLX.pdf