Water Filter Man Ltd's Blog

Online Shop www.waterfilterman.co.uk

How to change Reverse Osmosis Filters

This tutorial explains how to change the filters inside a standard Reverse Osmosis Water Filter system. This is the type of system most people will be familiar with as it is the traditional design and the most widely available model of RO system.

5 Stage Reverse Osmosis Water Filter


Firstly lets looks at what filters we have in the above system. Each pod contains a 10″ long water filter cartridge, from left to right there will usually be the following internal filters: FEED WATER COMES IN >  POD 1 CONTAINS SEDIMENT FILTER  >  POD 2 CONTAINS CARBON (GAC) or CARBON BLOCK FILTER > POD 3 CONTAINS CARBON BLOCK FILTER.   From here the water will then travel through the Reverse Osmosis Membrane, and then either straight into the tank or through the Post Carbon Filter / Alkaline or Mineral filter cartridge (if your system has one).

These Filters will look similar to this in order:

10 inch Sediment Filter

10 inch Sediment Filter

Granular Activated Carbon Filter

Carbon GAC filter

Carbon Block water filter

Carbon Block water filter















From here the water will then pass through the Reverse Osmosis Membrane (which is inside a filter housing horizontal on top of the other 3 pods), and then finally through the post carbon filter:

Reverse Osmosis Membrane

post carbon water filter

post carbon reverse osmosis water filter








Once you have identified the above filters you can use the following steps to change them. Note that the reverse osmosis membrane would not normally be changed unless necessary (such as if it is years old or the TDS is increasing / it has high usage)


RO Pre-Filter Change Instructions

  1. Turn off incoming water to system (either at the mains clamp or the inline valve on the mains pipe to the system if you have one)
  2. Turn off Tank Valve
  3. Turn on the water filter tap / water filter lever on your 3 Way Tap to release pressure, then turn off the tap
    1.  Unplug power for pump if you have a pumped unit
    2. Disconnect all pipes to the system and lay the system flat on the sink draining board. (you may wish to use a towel when disconnecting the pipes as water can drip out the system – mostly from the waste water pipe) to disconnect pipes if you are using push-fittings you simple pinch the little collect that sticks out of the push fittings down against the fitting itself, then pull the pipe out. If your system has screw type fittings (jaco fittings) then just unscrew these and pull the pipe out.
    3. Loosen the three big pods with a 10” filter housing spanner, and remove by hand. (if you don’t have one of these spanners you can try a adjustable rubber grip but these pods can really seize on)
  4. Identify filter type and Remove + Replace filters one at a time with the same filter type (the order will be Incoming Flow > Sediment Filter > Carbon GAC > Carbon Block
  5. Then tighten the pods back onto the system making sure the internal rubber gasket is still in place in each pod
  6. Only use the spanner to tighten the pods on a little bit so that they are on firmly, do not over tighten or they may be very difficult to unscrew upon next filter change.
  7. At this point it is recommended to flush these pre filters. To do this connect the mains water feed pipe to the system, and disconnect the pipe from where it comes out of the last big pod (the carbon block filter) and flush water through these new filters until it runs clear – this just helps prolong the life of your reverse osmosis membrane.
How to change the Reverse Osmosis Membrane (if required)
  1. The Reverse Osmosis Membrane sits inside a filter housing laying horizontal across the top of the system and is usually clipped into place.
  2. Simply disconnect the pipe from the end of the housing with the screw cap, and unscrew the cap (you may need a Reverse Osmosis Housing Spanner for this)
  3. Pull out the old filter (with pliers if needed) and slot in the new filter
  4. Screw the cap back on and push the pipe back in
Changing the Post Filter – Post carbon / Alkaline Filter / Mineral Filter
  1. The final filter (post carbon/Alkaliser/mineraliser cartridge) will have a Tee connector on one end, connecting to the system and the tank, and an inline connector on the other end, which goes straight to the tap (usually however this configuration can differ, best thing to do is replace with a new filter like for like where your old one was).
  2. Simply unscrew the fittings / or release them if push fittings, and put in your new post filter – making sure you follow the flow direction arrows so they match
  3. Put system back into place and reconnect up
  4. Flow through the system several gallons of water to flush out the new filters



  • Make sure all push fittings are in completely and when pulled on stay in place, you should feel them slide into place when done correctly.
  • Make sure pipe is smooth at the end when reconnecting the system, if not cut the end off so that it is smooth – replace section of pipe if necessary otherwise it may leak.
, ,
October 7, 2011 at 9:39 am Comment (1)

How to change a fridge filter

Fridge Filter Installation Instructions


This guide will describe how to change a fridge filter on american fridges which use an external in-line water filter cartridge.

Note: This guide is for the newer type of filters which use push fittings built into the cartridge. This may be different to you old existing filter which may have screw stem fittings. If this is the case all you need to do is cut the pipe before and after your existing filter to completely cut it out (follow installation steps below). This new type of filter does not need these fittings since it has push fittings built in.

*important note on push fittings* ensure the pipe is completely smooth and free from burrs around the ends where it will be pushed inside the new cartridge, otherwise slow leaks may occur, if pipe is not smooth cut out the burred bits until a smooth section is present.



Installation Steps

*Firstly please remove the blue sealer fittings from either end of the new cartridge (if present, if not continue to step 1) – check by looking in the hole at either end that the blue sealers have not been pushed into the cartridge during transit, if so please carefully remove them, they can just be pulled out.

1. Turn off the water supply to your fridge.

2. Release pressure from the fridge by drawing some water from its dispenser.

3. Put a bowl underneath your old filter to catch any water, and remove the pipe from your old filter / cut the pipe before and after the cartridge if it has screw fittings.

4. Push the tubing from the feed into the new cartridge in direction with the flow arrow imprinted on the cartridge. Direction is: FEED>CARTRIDGE>FRIDGE. Make sure the pipe is pushed firmly into the cartridge and is

gripped, if done correctly you can usually feel it slide into place.

5. Before connecting the filter to the fridge, hold the new filter over the bowl and open the inlet valve. Let water run through the filter for 5 minutes constant flow to flush out the carbon fines from the new fridge filter.

6. Once flushed, turn off the valve, and connect the other end of the filter cartridge to the fridge, and open the valve again.

7. Check for any immediate leaks, if any are present ensure the pipe is firmly pushed in the push fittings and that the pipe is smooth and free from burrs. Then double check again after several hours to ensure there are no slow leaks.

8. Be sure to check out www.waterfilterman.co.uk for your replacement filters.


Thank you for reading our guide on how to change a fridge filter



The information contained within this document should not be considered as professional repair or installation advice. Water Filter Man Ltd is neither responsible nor liable for any plumbing work done on your behalf; any suggestions of procedures are listed purely for informational purposes only.

, ,
October 2, 2011 at 10:43 pm Comments (4)