A reverse osmosis system is one of the most reliable ways to get clean, great-tasting water at home. Like any appliance that works day after day, things can occasionally go sideways.
At Aquasure, we hear from homeowners all the time who notice a drop in water flow, a strange taste, or a puddle forming under their sink. The good news is that most reverse osmosis system troubleshooting issues have straightforward causes, and many can be resolved without calling a technician. This guide walks you through the most common problems and how to address them.
Reverse Osmosis System Troubleshooting: Where to Start
Before getting into the specific problems, it helps to understand how your reverse osmosis system works at a basic level. Water passes through a series of pre-filters, then through the RO membrane, and finally into a pressurized storage tank. From there, it moves through a post-filter and out of your dedicated faucet on demand. When something goes wrong, it almost always traces back to one of these stages: pressure, filtration, or a valve.
Start with the simplest checks first. Is the feed water valve fully open? Is the tank valve open? Are your filters overdue for a change? These small things cause more problems than most people expect.
Low Water Flow or Weak Pressure
This is probably the most common complaint. You turn on the faucet and get a trickle instead of a steady stream.
The likely culprits are:
- Clogged pre-filters or sediment filters: These become restricted over time and need replacing every 6 to 12 months
- Low tank pressure: An empty RO tank should read 7 to 8 PSI; anything lower and the water won't push out properly
- Low household feed pressure: The system needs at least 40 PSI coming in to function well, with 60 PSI being the sweet spot
- A fouled RO membrane: Membranes generally last around 24 months, and a clogged one dramatically slows production
If tank pressure is the issue, drain all the water from the tank first, then use a bicycle pump to bring it back up to 7 to 8 PSI. Add air gradually and check with a pressure gauge as you go. If the tank won't hold pressure, the internal bladder may be ruptured, and the tank will need to be replaced. A booster pump is worth considering as a longer-term fix for consistently low household pressure.
Your Reverse Osmosis System Keeps Running
A system that constantly drains water is wasteful and usually points to a valve problem. Understanding this issue is a key part of any troubleshooting process for a reverse osmosis system.
Normally, the auto-shutoff (ASO) valve closes once the tank reaches the correct pressure, stopping water from flowing to the drain. When the system keeps running, the ASO valve has likely failed and isn't registering a full tank.
A faulty check valve can also be responsible. To narrow it down, turn the tank valve off and watch whether the drain flow stops. If it does, the issue is with the ASO or check valve. If it doesn't, the problem may be elsewhere in the line.
A missing or failed flow restrictor is another common cause. Without it, water rushes to the drain rather than building pressure through the membrane, and you'll usually hear a lot of noise along with the constant draining.
Tank Not Filling Up
If the tank is filling slowly or not at all, start with your filters. Clogged pre-filters are the most frequent cause, as restricted flow means less water reaches the membrane and the tank fills at a crawl. A clogged membrane has a similar effect; what normally takes 2 to 4 hours to fill could stretch to 4 to 6 hours or more.
Tank pressure can also work against you here. If the air pressure inside the tank is too high, incoming filtered water can't enter. Drain the tank fully and check the pressure before assuming the membrane is to blame.
A closed or partially open supply valve is worth checking, too. It's an easy thing to overlook after a filter change or any maintenance work.
Strange Tastes or Odors
Clean RO water should taste neutral. If something seems off, the filters are usually the first place to look. Old carbon filters lose their ability to absorb chlorine and other compounds, and the result comes through in the taste. Replacing filters on schedule (every 6 to 12 months) prevents most of these issues.
If the filters are fresh and the problem persists, the RO membrane may be compromised. A damaged membrane allows more dissolved solids to pass through, which can affect both taste and odor. A TDS meter is a useful tool here; a noticeable spike in readings after a filter change points directly to membrane failure.
Homes on well water may also notice an occasional sulfur-like smell. Dissolved gases can concentrate through the membrane, and this is something to investigate and address before installing any new components.
Leaks Under the Sink
Seeing moisture or a small puddle under your sink can feel alarming, but leaks are often minor and fixable. Quick-connect fittings are the most common leak points, especially after a filter change. Pressing the fitting in more firmly often resolves it. If the leak continues, the fitting may need to be replaced.
Filter housings are another area to inspect. A loose housing or a worn O-ring allows water to seep through. Close the feed valve, remove the housing carefully, check the O-ring's condition, reseat it properly, and reassemble. If the housing is cracked, replacement is the only option.
Air gap faucets can also drip when the drain line is clogged. Back pressure forces water out through the air gap opening. Clearing the drain line typically stops this.
Cloudy Water and Gurgling Noises
Milky or cloudy water straight from the faucet is almost always harmless. It happens when air gets trapped in the system, particularly after installation or a filter change. Let the water sit in a glass for 30 to 60 seconds; if it clears from the bottom up, you're looking at dissolved air, not contamination. Running the system for a day or two usually fixes it on its own.
Gurgling sounds during or after tank refilling are also normal to a degree, particularly in a new system. Loud or persistent gurgling points to trapped air, a misaligned tube, or a drain saddle that needs repositioning. Securing the tubing away from hard surfaces and fully opening the tank valve often significantly reduces noise.
Keep Your System Running at Its Best
Staying on top of maintenance is the most effective way to avoid most of these issues altogether. Replacing filters annually, swapping the membrane every two years, and sanitizing the system once a year goes a long way. Pairing your RO system with a water softener can also reduce the mineral load on your membrane and extend its working life.
Get in touch with us, and we'll help you get your system back to producing the clean water your household depends on.
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