We were having low pressure from the filtered water spigot in out kitchen, which is fed by a Hague 3500 RO system in the basement. It is a rental, and I had never dealt with a system like this before. I found some pretty good youtube videos (https://www.youtube.com/watch?v=gc-qmgzAUiA) explaining how to change the filter. So I bought some off Amazon (https://www.amazon.com/dp/B00JLD81OE) and replaced all 3 filters (but not the R/O membrane).

I pre-rinsed the pre-filter and the prolonged contact filter as instructed, and both allowed water through quite well and everything went as expected. But when when it was time to pre-rinse the carbon post-filter, the video indicated that I should install it and just turn on the tank pressure and let it rinse through the system (and expect to get some ugly bubbly water out of the faucet for a bit). I did that, and there was a little bit of bubbly water that came out (though it wasn't black), but then that tapered off and now I get nothing out. I've left the tank and the input feed valves open, but I get no water. I'm curious what might cause this.

My tank seems to have approx 10psi (and the video said that 7 is normal), so unless my car tire pressure gauge is way off, that isn't the problem.

I've seen a couple other questions similar to this but none seemed to have an answer (though one person said that they replaced their ASV and then after 2 days, it started working again).

Everything was working fine before this, except for the slightly low pressure, which started about a week ago.

UPDATE 1: After about an hour, a dribble of water is now coming out.

UPDATE 2: The following morning, there seemed to be good pressure. I drained the tank (to follow the original instructions of using a tank's worth of water to pre-rinse the final new filter), and will check again in a few hours to see if it has refilled.

This is our setup (like I said, in the basement, and feeding a separate small faucet in the kitchen):

Wall mounted RO system

RO pressure tank on the ground

  • Faucets usually have small screens in them. Possible they are blocked. Usually easy to undo with soft rag around the end and pliers. Block the drain so small parts do not get lost. If faucet not blocked, then need to work back.
    – crip659
    Commented Apr 18 at 21:18
  • you have a custom tank, why? take a close look at it
    – Traveler
    Commented Apr 18 at 23:44
  • @Traveler this is a rental - I did not install this system. It is, however, a much larger tank than the little ones I've seen in under sink units. I don't know if it needs to be bigger (or have higher pressure?) since it is in the basement. I don't know enough about fluid dynamics to know what being in the basement will do to things.
    – Doug
    Commented Apr 19 at 0:43

2 Answers 2


Step be step troubleshooting. Have a bucket, turn off the main valve on the unit, disconnect one of the hose and monitor water flow. Repeat, repeat...

Double check the connections on the pressure valve regulator, the cylinder in the middle


It appears that it was just a question of time. Not sure why, but it seems like my pressure tank was close to empty when I went to change the filters. It is possible that clogged filters resulted in the inability to fill the tank (which might explain why we had low faucet pressure to begin with), and that it just took a few hours to refill. But everything seems to be back to normal now.

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