Filter Housing O Ring

Select either 2.5'' for white (or blue) domestic water filter housings (e.g. our Pearl/Oyster drinking water filters) - or 4.5'' for big blue water filter housings (e.g. our Moby/Doby mains water filters).

• 2.5'' cartridge - £4.99 - 84mm internal diameter
• 4.5'' cartridge - £5.49 - 138mm internal diameter

Take care with the dimensions of the O rings, these fit the housings for 2.5 inch and 4.5 inch filter cartridges.

If you are unsure about what you need or are looking for a different size please CLICK HERE to send us a message through our help desk and we'll do our best to help you out. We get a lot of requests for different sized o-rings. 

What is an o-ring?

An o-ring is a circular ring made of rubber. They're available in a range of sizes which are specified by the inside diameter and cross-section diameter. The o-rings we source tend to be made of nitrile rubber. It's a common material for o-rings because of it's good mechanical properties and it's resistance to lubricants and greases. 

What does an o-ring do?

In our case they prevent water leaking from the filter housing bowl. The o-ring is placed into the groove at the top of the water filter housing. It helps secure the bowl to the cap as the o-ring is compressed between two surfaces. 

Why do I need to change the o-ring?

You can tell if the seals start leaking, which is obvious, I know.

Even if there are no leaks you may find that the profile of the O ring becomes flattened because of prolonged time under compression. The cross section should be round and if it's not it may not seal easily.

However, we recommend that you replace the O rings every two or three years as a precautionary measure.

One of the main reasons for changing O rings periodically is that as they age and compress, the housing bowl needs to be tightened excessively. That leads to difficulty loosening the bowl from the cap next time the cartridge needs to be replaced.