Reverse osmosis FREQUENTLY asked questions 

What is Reverse Osmosis System?

Reverse Osmosis (RO) is one of the most effective water treatment processes that will provide clean, great-tasting drinking water for your home or business.

If you're looking for an affordable filtration system that will provide you with quality water, Reverse Osmosis can be a good system for you that provides superior filtration with low maintenance.

Bluonics Reverse Osmosis Systems

What should I look for when buying a reverse osmosis system?

There are 4 factors that you need to consider before buying a water filter system.

1-Water Pressure: Most RO units need at least 45 psi to operate correctly. If your pressure is lower than this, you might look for a RO with a Booster pump similar to this Bluonics 5-stage RO with a booster pump. 

2-Filtration Quality: The quality of RO filters can be measured by the total dissolved solids (TDS) of the filtered water against the source water. A regular RO removes up to 99% of over 1000 contaminants, including lead, chlorine, fluoride, arsenic, asbestos, calcium, sodium, nitrates, and more.

3-Flow Rate: Reverse Osmosis has a gallon per day (GPD) number that refers to the amount of water a unit can filter per day at an optimum condition. In most cases, the amount is about 10-20% lesser as stated.

4-Budget: Before purchasing a RO system, consider both the initial cost to purchase a system and maintenance costs to replace RO filters.

I have installed the 5 stage RO but the tank is not filling up.

Inspect the water-supply valve, ensuring it is in the fully-open position. If it is clogged or only partially open, the RO unit might not build up sufficient water pressure to operate.

Inspect the unit's supply lines. A kinked line will restrict water flow and prevent proper operation.

Open the unit's tap and allow the water to run until the tank is empty. Use a pressure gauge to check the air pressure in the tank. The pressure in an empty tank should be eight pounds. If the pressure in the tank is too high, water will be unable to enter from the filters. If the pressure is too low, the water inside the tank will not flow to the faucet

If these did not help, the problem can be with the tank bladder and you might need to replace your tank

How often do I need to change the filters in RO?

It depends on the water quality. We recommend to change the first 3 stages (Sediment, CTO carbon and Granulated) filters every 6 to 9 month to protect the membrane. The T33 Carbon filters on the top needs to be replaced every 2 years and for the membrane, you only need to change it every 4 years.

You can find the replacement filters here:

RO Filter Replacement

How long does it take to fill reverse osmosis tank?

It typically takes 2 to 4 hours to fill a standard reverse osmosis tank (2.8 gallons or 10.6 L)

How much water does a Reverse Osmosis system use?

All reverse osmosis system wastes about 2 to 3 gallons of water per gallon made. That means there will be about 2 gallons discharge water for every gallon of clean water produced.

Can I use waste water from RO system?

Waste RO water can be used for irrigation, but needs to be mixed with normal water to reduce its high TDS level. It can also be used to wash off utensils because salt content in it does not let leftover food get stick to utensil.

After installing the RO unit, water is continuously going to drain

When the RO fails to shut off after tank is full, drain water will continue to run. 

Sometimes, the input water pressure may be too low (below 40psi) to stop it from going to drain, if not it might be a faulty Auto Shut-off valve.

 I have installed my reverse osmosis per instruction but it is making a lot of noises

Reverse Osmosis system will make some slight noises as it processes water, even though faucet is off. This is due to the pressure change inside unit as it begins processing more water. Slight dripping/gurgle noise from sink drain is normal. 

Usually a new reverse osmosis drinking water system may have air pockets in it at first. When the system is first installed, there will likely be some air pockets within the system that will have to work their way out.

These air pockets can cause a sputtering effect in the water as it comes out of the faucet. These pockets of air will likely disappear in a relatively short amount of time.

How to hook up a fridge or ice maker to a RO?

Just put a T-valve in the line that is going to your faucet and hook the ice maker line to the other side of the T fitting. 

What does RO Auto Shut off valve do? 

Auto Shut-off valve stops the flow of water when the storage tank is full. 

Can I use RO to remove chlorine from my city water?

Reverse Osmosis can remove up 99.9% of Fluoride and Chlorine that is in your tab water.

Do I need to flush the filters every time I change them?

Yes, after installing the system or changing filters, remove the membrane, turn the blue valve on the top of the RO to ON position (Clockwise) and let the water run for few minutes (5-10min) till the water is clear. 

Turn the valve back to OFF position , put the membrane back in the big white housing on the top and start enjoying your fresh clean water.

What should be the pressure for my RO tank?

In an empty tank, air pressure should be 7-10 psi. In a full/heavy tank, air pressure should be 30-40 psi.

I had my RO unit for a while and now it’s started to leaks between the canister and the cap.

If you take out the filter and put some lubricant on the O-ring seals it should stop the leak . if this doesn’t help, you need to change the O-ring seal.

We installed the RO for our Cabin and after RO Filtration, the TDS is still too high.

First please make sure you flush the tank after you installed it. Easily drain out all the water from the tank and let it fill again. That should help to get a lower TDS. 

Remember RO reduces the TDS down by 90%, so if you have a TDS of 500, you will still have 50 TDS after running the water through the RO system. (TDS= Total Dissolved Solids)

I was wondering about the ability of Bluonics RO units to filter salt water. I have a 26 ft cruiser, and wanted to use this unit to make fresh water would it be able to handle salt water?

No it can not. What you need a desalination unit not a RO.  RO membrane will remove 90% to 95% of the sodium only.

 I cannot lock the tube in those white quick connect fittings. 

Take off the blue clip and push the hose in a little hard. Sometimes it seems like it is all the way in, but if you wiggle the hose and push at the same time it goes in a little farther where it seals. 

To release the tube, easily remove the blue clip, push the white ring inward with your nail and release the tube.

Watch the video here.

Can my RO use an Alkaline filter?

Yes, you can switch the upper T33 Carbon filter for our Alkaline filter for better tasting water by adding minerals from the water

Can an RO unit be laid on its back?

Yes, a reverse osmosis system works normally laid on its back.

Does the RO come with a faucet?

Yes, all RO units include a brushed metal faucet.

Reverse Osmosis troubleshooting Tabel




RO tank not filling up

Feed water pressure below 40 psi

Tank valve closed

Feed water valve closed

Tank pressure too high

Membrane or filters are clogged

Need a booster pump or increase water pressure 

Open valve

Open valve

Release tank pressure


Slow water flow from faucet

Storage tank pressure too low

Tank air bladder is damaged

Ro Membrane or filters are in clogged

Membrane not properly seated

Clogged flow restrictor

Feed water valve closed

Tank valve closed

Add some pressure to the tank 7psi-10psi

Replace tank

Replace membrane


Unclog or replace

Open Valve

Open Valve

Water constantly goes down the drain

Clogged flow restrictor

Defective shut-off valve

Clean or replace

Replace ASO valve

Noisy air gap faucet or drain

Air pockets in Ro after installation

Tank not filled yet 

New system or filter replacement

Bent tubing

Tilt the system and let it run for a while

Wait 2-3 hrs until tank is filled

Will subside over time

Straighten all water lines

Cloudy water

Trapped air in the system or filters

Will subside over time

Bad water taste

Depleted filters or membrane

Fouled membrane

Stagnant water

Replace Filters

Replace + clean system periodically

Flush entire system


Worn out or Misplaced O-ring


Noisy Gurgle

Too much water to the drain

Locating the saddle on the crossover

Pump Not running

Low feed water pressure

Loos power connection

Transformer burnt out 

Need a booster pump or increase water pressure

Check power supply


Tubing Leaks

Incorrect connection

Check and reinstall 

Pump is on but no water

Pre Filters clogged