Water hardness is a big concern in Phoenix, Arizona. Because of this, a reverse osmosis system is of great value here. But just because you have one installed under your sink doesn’t mean you’re reaping the rewards. In fact, many RO filtration problems simply go unnoticed.
Unless you’re frequently testing your water or investing in proper maintenance, the dispensed water may not be much better than that which flows from the garden spigot. Although a filtration system can easily replace the cost of bottled water, it’s worthless when it’s not working properly.
What Usually Goes Wrong with RO?
With that being said, let’s talk about some of the common RO issues that hinder water purification – starting with the most noticeable first.
1. The Flow of Water is Minimal.
When your system is supplying nothing more than a trickle, you’re probably dealing with one of the following RO filtration problems: A clogged membrane, ruptured tank bladder, low pressure, a kinked water line or an empty tank. Since a full tank should weigh around 20 pounds, check this first.
From here, inspect your water lines to see if any need to be replaced or straightened out. If all looks good, you’ll want to test the pressure of the tank. You can use a bike pump or air compressor to see if it measures 35-40 psi (6-8 psi if empty).
RO Bladder and Membrane Problems.
In most cases, slow-flowing-water points to an issue with the bladder inside the tank. When it ruptures, pressure diminishes. In turn, your RO cannot effectively pump out filtered water. You can try to see if the bladder will hold air – but if it doesn’t, a tank replacement is your only option.
Clogged membranes are also common in Phoenix when they’re over 5 years old or pre-filter carbon cartridges aren’t changed out every 90-180 days. If hard water minerals are able to accumulate, the system becomes saturated. The good news is, this is easily preventable.

2. Unusual Reverse Osmosis Noises.
Most people realize they’re having RO filtration problems when the system oddly gurgles, hisses or clicks. Since the plumbing is predicated on pressure, the sounds point to improper tubing.
Gurgling normally occurs when the drain line isn’t level with the drain pipe. Any low point can create a siphon (that gurgles) due to leaking water at this connection. The only other time you should hear this type of noise is when the pressure tank is filling.
Strange Sounds Are Mostly Problematic.
While hissing can be the result of new filters (which is normal for 1-2 days), it’s also caused by excessive air pressure in the drain or air gap. Unless water flow is cleared in the drain lines or tubing, the sound will resume. If the system clicks, then RO tubing is probably too long and air bubbles are prevalent.
3. The Tank Is Not Filling Up With Water.
Before jumping into the concerns, it’s important to point out that high water usage can leave you with an empty tank. But when this isn’t the case, a clog or low water pressure is usually the culprit.
Like we mentioned before, water hardness can easily clog up the membrane. This obviously leads to a number of RO filtration problems. If you’re constantly replacing the membrane, you might want to consider installing a water softener.
Upgrade Your Filters or Address Water Pressure.
The RO tank will also struggle to refill when the pre and post filters (granular activated carbon, semipermeable membrane and carbon polish) are clogged. Aside from using a softening system, additional RO filters can help.
The last cause of inadequate filling is bad water pressure. When it’s high, water can’t make it to the tank – so you might want to consider buying a pressure reducing valve. Low pressure hinders the entirety of the process (see above).

4. A Leak During RO Filtration.
At the end of the day, one of the more common RO filtration problems is a leak. Whether it involves the air gap or the faucet, it’s usually an easy fix. Either way, as soon as excess water is discovered, the cold water supply needs to be shut off.
The air gap leaks when there’s debri in the drain line or the connection between the faucet and the drain saddle is too long. Like we mentioned above, this can create a hissing noise. To address this, clean out the drain and saddle or straighten the tubing.
There Are Multiple Solutions to RO Leaks.
The cause of a leak at the faucet can also be an air gap issue – but it may be as simple as a loose connection or faulty faucet. While the ladder requires a replacement, tightening your plumbing should do the trick. If it doesn’t, you’ll want to make sure the drain hole and saddle are lined up and RO tubes are inserted properly.
5. The System Smells, Tastes Funny.
Another noticeable area of concern is poor tasting water. Since the reverse osmosis process is meant to purify, this should be a red flag. In most cases, an array of contaminants are creating unhealthy drinking water. So, you’ll want to discontinue use, discard the water, and at least replace the filters.
Sometimes, remineralizing the water can help with the taste. But if you want to avoid this problem and its consequences (like biofilm exposure), you have to maintain the system and sterilize it on occasion. When you don’t routinely replace the membranes and filters, the water is going to taste funny.

Why Does Water Stink Like Fish and Eggs?
For the most part, unwanted smells are caused by chloramine (a mixture of chlorine and ammonia mixture used to disinfect public water), the combination of cadmium and barium, or hydrogen sulfide (rotten eggs). A fishy stench can also be attributed to summer algae growth in warm water sources with sun exposure.
No matter what’s creating the smell, you need to quickly replace your filters and discard the water that’s in the RO tank. Purchasing a system with a modular filter configuration will help you sidestep the nasty effects of contaminated water.
6. The RO System Won’t Stop Draining.
When water continuously drains, you’re more than likely dealing with a membrane, flow restrictor, check valve or ASO valve issue. Nonetheless, this can be one of the more complicated RO filtration problems that Phoenix residents face.
Channeling Water Flow Is Important.
As you well know by now, the membrane is a delicate component that requires routine inspection and care. An outdated or damaged membrane that’s exposed to excessive alkaline, mold growth or high temperatures cannot be expected to perform adequately.
The same can be said for the flow restrictor as it maintains the pressure of the membrane. In fact, both need to be replaced at the same time. When the restrictor is the wrong size or malfunctioning, the flow and volume of wastewater is altered.
When You May Need to Replace RO Parts.
When the check valve is damaged, the RO system cannot restrict the flow of water or hold enough pressure to shut the system down during failure. A faulty ASO (automatic shut off) valve has similar consequences because it’s controlled by tank pressure. If either is allowing unimpeded water into the drain line, a replacement is imminent.

Enjoy Your Phoenix Drinking Water.
Whether you’re a reverse-osmosis-advocate or considering the purchase for the first time, understanding your equipment is important. If you want the system to last 15 years, then you have to take care of it and know how to address RO filtration problems that arise.
This is where a trustworthy relationship with a quality plumbing company comes in handy. While there are some drawbacks to desert-living, the ability to overcome the hard water here can be rather refreshing. To learn more about our services and capabilities, feel free to give us a call or fill out a contact form below.