Easier to help if you tell us where it's leaking...

If the faucet leaks from air gap this can be caused by a crimp in the drain line, a restriction in the drain line, or a clogged drain tube. If there is a crimp in the drain line, check and straighten out the tubing.

Call Watts Premier @ 800-752-5582. They have good tech support and they speak English.

Sorry, the leak is at the spigot where it is now a slow drip.

If that's the leak, like it won't shut off and dribbles, then I see no parts available for that. IIRC the black lever can be removed after pulling the spout then remove the valve piston to clean it and the seat. Use food grade silicon grease on the o-ring(s).

I'd contact Watts Premier and see what they say. They might replace the faucet under the 3 year warranty.

Curious, how long has the RO been in service? Have you been doing any routine maintenance? Have you been checking TDS before and after the RO to see if it is operating correctly? did this leak just magically happen or did it happen after doing something?

You might want to check your water pressure in the home to make sure it;s not over 80 psi. Less than 70 and more than 40 is average.

Thanks for responding.
The faucet is 1st generation, no lever as the replacement has; it is a push-button at the spigot and the system is at least 6 years old ; have been servicing it regularly so looks like simple washer wearout.

I suspect a washer inside the spigot assembly but can't see
how to remove it.

I wanted to avoid replacing it because I am too lazy to.
The replacement is cheap enough.

"To repeat myself... you might want to check your water pressure in the home to make sure it's not over 80 psi. Less than 70 and more than 40 is average. This faucet drip might be the first symptom of a failing PRV in your plumbing system and line pressure is so easy to check."

No PRV just town water and not so easy to check.

Will just do the Watts upgrade when the leak gets worse.

Just wondering how the design which has a spring loaded
closure can shut off water without a seal washer of some kind.

Thanks for your interest.

There are pressure gauges that screw on a hose bib and you can check house system pressure in 10 seconds. HD and Lowes sell them for about 10 bucks.

There is a washer but the faucets are not designed to be dissembled. On the ones where the lever can be removed the seal is set into the end of the piston and won't come off. Often there's just some crud and cleaning the seal and seat does the trick. If you can figure out how to get to the seal that's all you might need to do.

Thanks, I ordered the replacement for a big $13 and now it will sit until I can't bear the dripping or my wife sends divorce papers , whichever comes first.

Once the replacement arrives the dripping will stop.

Just like generators. Once you get them , no more power failures ( I wish)

Well, I didn't exactly order the new faucet but delayed doing so, since I was confronted with another issue, namely low water output.
I resolved that by repressurising the holding tank and
installing the carbon and sediment filters.
And low and behold, the dripping stopped.

But, I got interested in the drainage problem and found that you lose 6 gallons for every gallon of yield, which is probably common for most RO systems.

But in my case the drain continued to run well after the tank was full, indicating a failed shutoff system.

In looking for a replacement ASO valve I find that they use the input to the membrane filter for the high side and the tank line ( blue) as the low side. Problem is my older WP-5 unit is enclosed so I do not have access to membrane input.

So my question is:
Can I use the house water for the high pressure source on the ASO valve?

Thank you for your valuable input.