Troubleshooting Your Under-Sink RO System: Common Issues & Fixes

There's nothing worse than going to fill up your water glass and getting barely a drip from your RO faucet, or worse – water that tastes funky even though you have a filter. If your under-sink RO system is acting up, you're not the only one dealing with this headache. Most problems with these systems are actually pretty common and way easier to fix than you'd think. Before you call someone or assume your system is toast, some basic under-sink RO system troubleshooting can usually get things working again.

What Should You Check First? Your Under-Sink RO System Troubleshooting Basics

Before you start taking apart your under-sink RO system, check these basic things first. These simple steps can solve most problems without any complicated repairs.

Check Your Water Supply

Make sure your main water supply is working by turning on other faucets in your house. If water pressure is low everywhere, the problem isn't your RO system. Also check that the main water shutoff valve under your sink is fully open – sometimes these get turned accidentally.

Verify Power

If your under-sink RO system has electric parts like a booster pump or UV light, make sure they're getting power. Check that the power cord is plugged in tight and test the outlet with another device. Look for any power switches that might have been turned off accidentally.

Inspect Tubing for Kinks

Look at all the plastic tubes connected to your system, especially where they bend around corners. Kinked tubing is one of the most common causes of low water pressure. The tubes should have smooth curves without sharp bends or pinched spots. If you find a kink, gently straighten it out.

Confirm Filters are Installed Correctly

Double-check that each filter is seated properly and screwed in right. Make sure you have the right filters in the correct order – usually sediment filter first, then carbon filters, then the RO membrane. Also check that you removed any plastic wrapping from new filters.

Check Tank Pressure

If your system has a storage tank, it needs the right air pressure to work. The tank should feel firm when you tap it, not squishy or rock hard. Most RO tanks need about 7-8 PSI when empty. You can check this with a tire pressure gauge on the air valve at the bottom of the tank.

How to Fix Common Under-Sink RO System Problems

Having gone through basics, we can now tackle special issues. Most will fall within a few universal categories, and having some idea what to look for will make repairs pretty evident.

Problem 1: Low Water Pressure / Slow Flow from RO Faucet

If your RO faucet is only trickling out water, begin with the likely offenders. See if your filters need replacement -- old or plugged filters are usually the cause of sluggish flow. Check your storage tank pressure as well; if it's below par, then your water can't push out. Ensure all your connections on your tubing are snug and that absolutely nothing's kinked or pinched. If you incorporate a booster pump, then perhaps this is failing and requires replacement.

Problem 2: Water Tastes or Smells Bad

Bad-tasting water from your RO system usually means it's time for new filters. Start by replacing your carbon filters, which remove taste and odor. If that doesn't work, your RO membrane might be worn out and letting contaminants through. Check your storage tank too – if it's old, bacteria can build up inside and make the water taste funky. Sometimes flushing the system for a few minutes helps clear out stagnant water.

Problem 3: The RO System is Leaking

Leaks are scary but usually easy to fix. Check all your connections initially – most leaks occur where tubes attach to fittings. Seat the tubes in tightly or replace any broken fittings. Check your filter housings to ensure they are screwed on tightly and that O-rings are not cracked or gone. If drips occur from the base of the faucet, tighten connections or replace worn seals.

Problem 4: Too Much Water Running to Drain / Constant Drain

If your system still runs water down the drain, then your automatic shut-off valve is likely jammed or broken. It's designed to turn off the flow down the drain when your tank's full. Try turning your system off and then on again to restart it. If this doesn't work, then your shut-off valve will need to be cleaned or replaced. Check your tank pressure too – if it's not right, it can confuse your shut-off system.

Problem 5: No Water from the RO Faucet

When nothing comes out at all, work backwards from the faucet. Make sure the faucet valve is actually opening properly and that the tube isn't disconnected underneath. Check that your storage tank valve is open and that the tank has water in it. Look for any completely blocked filters or a shut-off valve that's stuck closed. Sometimes the system just needs time to refill if the tank was recently emptied.

When Should You Call a Professional for Your Under-Sink RO System?

Sometimes the best troubleshooting advice is knowing when to stop and call someone who knows what they're doing. Don't feel bad about getting help – some problems really do need professional expertise.

Situations Requiring Expert Help

While many RO system issues can be fixed at home, certain problems are beyond typical DIY capabilities and require professional intervention. Trying to tackle these issues yourself could make things worse or even create safety hazards.

• The same leak keeps coming back even after you fix it multiple times.
• Water is coming from weird places inside the system where you can't see any loose connections.
• The electric parts stopped working and you already checked that they're plugged in properly.
• Several different things are breaking at the same time, which usually means a bigger problem.
• You're dealing with error codes or problems you've never seen before and can't figure out.
• You need to change the actual plumbing connections to your house's main water pipes.
• You can't find or identify the replacement parts your system needs.

What Information to Provide Your Technician

Being prepared with the right details will help your technician diagnose the problem faster and potentially save you money on service time. Having this information ready before you call will make the entire process smoother.

• Tell them the brand, model, and how old your system is.
• Explain exactly what's wrong and when it started happening.
• Describe what you're seeing, hearing, or tasting that seems off.
• List everything you already tried so they don't waste time repeating it.
• Let them know if your house has good water pressure or if it's always been weak.
• Mention when you last changed filters and if you used the right ones.
• Say whether the problem happens all the time or just sometimes.

4 Tips to Avoid Future Issues with Your Under-Sink RO System

Preventing trouble from arising on your RO system is a lot easier and cheaper than fixing breakdowns. A little regular maintenance does wonders to keep your system running efficiently and your water still tasting great.

1. Replace Your Filters on Schedule

Everyone forgets about filters until things go awry, but keeping on top of replacements is the absolute best thing that can be done to a system. Pre-filters need to be replaced approximately every 6-12 months, while the RO membrane will last a maximum of 2-3 years if taken care of properly. Put it on your calendar or program phone reminders so this will not be forgotten. If filters become too aged, they cease to function and can potentially turn your water quality into a worse state.

2. Sanitise and Clean Your System Regularly

Your RO system will need to be cleaned adequately every 6-12 months to keep things functioning properly and to avoid bacterial growth. You can buy sanitizing solutions made specifically for RO systems, or most manuals will have cleaning directions. It usually involves running a cleaning solution through the system and then flushing out entirely with new water. It only takes about an hour, but it prevents a lot of hassles later.

3. Monthly Check Your System for Problems

Every month or so, take a minute or two to glance around your system to spot any apparent trouble. Look for spots or pools where water's collected that could signal leaks, listen for strange sounds, and verify that all your tubing appears to be in good condition. Check your pressure at the RO faucet to ensure it's still flowing easily. Spotting minor difficulties early helps you repair them while they remain minor and avoid costly difficulties.

4. Maintain Your Water Pressure within the Proper Range

Your RO system requires a constant level of approximately 40-80 PSI to function effectively. If your home pressure is below this range, then your system will not yield sufficient water or function too slowly. If this level rises too high, then parts will be damaged and wear out prematurely. It's an easy task to check your home's level of pressure with a simple gauge available anywhere a hardware store is and add a pressure regulator if necessary to remain within a protected range.

Fix Your Under-Sink RO System Problems Without the Stress

Your under-sink RO system troubleshooting doesn't have to be complicated or expensive – most fixes are actually pretty straightforward once you know what to check. Work through the basics first, then focus on your specific problem using the right approach for each issue. Call a professional when things get too complex, but handle the simple stuff yourself to save money. Check your system regularly and stay on top of filter changes to avoid most problems in the first place.