No Water After Changing Reverse Osmosis Filters

No Water After Changing Reverse Osmosis Filters

Reverse osmosis (RO) water purification systems are a sophisticated piece of kit designed to eliminate up to 99% of all impurities present in unfiltered tap water. However, RO filters only have a limited lifespan and require replacement, on average, once or twice a year. If you have recently changed your filters and find that your reverse osmosis system isn’t producing any water, here’s why.

If there is no water coming out of the faucet, after changing reverse osmosis filters, it is likely that you haven’t waited long enough for the system to produce enough water. Other common reasons for no water are due to incorrect air pressure, low water pressure, or because the saddle valve isn’t turned on.

For many homeowners in North America, reverse osmosis units offer the perfect solution to clean, healthy, and safe water. Just like any water purification system, however, problems can arise. No water, a low flow rate, and a lack of water filling up in the storage tank can all happen after a filter change. Why does it happen and how can it be resolved? Well, let’s find out!

Read my comprehensive article about reverse osmosis.

7 Reasons for No Water Flow After Changing RO Filters

Sterilizing or replacing an RO filter can be done on your own. Learn how by watching this helpful video.

If you are confident you have replaced your reverse osmosis filters correctly and the issue of no water is not a result of improper installation, here are some other possible reasons as to why this could be happening and how to remedy it:

1. Not Enough Time Has Passed

If you have used a UV filtration system in the past, you are likely used to having instant access to purified water. However, RO systems don’t work this way as their filtration is a lot more thorough.

On average, it takes four hours for an RO system to produce 2 gallons of purified water. That is about 2-3 ounces of water per minute. This is why you need to wait for a minimum of four hours before using the RO system again after a filter change.

2. The saddle valve is turned off

Before you can change the filters, you need to turn off the inlet supply or saddle valve that stops water coming in from the mainline. It is easy to forget to turn this valve back on after a filter change and this could be the reason behind your no-water issue.

3. The storage tank isn’t filling up or has a low water level

The storage tank valve also needs to be shut off before the filters can be replaced. Make sure the valve is turned back on otherwise water will not fill up inside the storage tank. This will also lead to no water coming out of the faucet.

If the storage tank is nearly empty you will likely get no water coming out of the faucet. Wait for the tank to fill up before using the unit again.

4. Incorrect air pressure in RO storage tank

An RO storage tank is made up of two chambers, one for air and one for water, separated by a bladder. Since a storage tank relies on pressure to flow water in and out, any imbalance of that pressure will cause problems.

Low pressure inside the tank won’t allow water to flow through the tubing and through the faucet resulting in no water.

If the tank pressure is too high, water that is passing through the filters and membrane won’t end up in the storage tank and instead would simply drain away.

To deal with this issue turn off your reverse osmosis unit and drain out all the water in the storage tank. Use a pressure gauge to then measure the air pressure in the tank. If the pressure is less than 8 PSI this is a likely reason why you are getting no water.

To repressurize the tank, simply connect a bicycle pump to the air valve (found near the base of the tank) and fill it up until the pressure reads 8 PSI.

5. Poor quality of domestic water from the main line

If you experience low water flow coming out of the faucet, 6-8 weeks after a filter change, it is highly likely that your water supply is impure and causing the filters, and perhaps even the membrane, to clog up.

In this instance, the best course of action is to get both the mainline water and your reverse osmosis water tested immediately.

6. Low water pressure

In order for your RO system to work, the minimum water pressure it requires coming from the mains is 40 PSI. If the pressure is lower than that, the unit won’t work as the water won’t have enough force to pass through the powerful and ultrafine filters.

If this is a persisting problem, the best solution would be to install a booster pump to ensure pressure remains over the 40 PSI mark.

7. Ruptured RO tank bladder

When turning on the faucet, if the first few ounces of water flow out at normal pressure but then quickly turn into a trickle, this is a very clear indication that the RO air bladder is ruptured or damaged.

This can happen at any time and the fact that you have just changed your filters may just be a coincidence. Unfortunately, there is no way to repair or replace a ruptured air bladder and the only solution is to buy a replacement storage tank.


Q) After how long should I change my RO filters?

Most reverse osmosis filters have the capacity to filter 500 gallons of water before requiring replacement. For the average four-person household, RO filters typically last for 9 months to a year depending on consumption.

Q) Are there other reasons I’m experiencing this No Water problem?

The above are the most common reasons for a no-water issue. However, if none of those is the cause of the problem it is best to call in a water treatment expert as there might be an issue with the RO membrane or kinks in the water line.

Final Thoughts

RO units are generally extremely reliable and any fault that arises in the system is likely due to a small and easily fixable issue. However, there are always exceptions. If you are continuing to have a no water issue, despite checking up on all the points mentioned above, it would be best to call in the experts to give your unit a thorough inspection.

Boch Richard

Richard Boch is a chemical engineer responsible for designing water filtration systems for industrial and residential customers. He has more than 20 years of experience with ion exchange, activated carbon, and reverse osmosis. Richard's expertise has made him a go-to source for municipalities and businesses looking to improve their water quality. When he's not working, Richard enjoys spending time with his wife and two young children.

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