The ten inch housing is the default size in domestic water filtration, and the number refers to the cartridge length rather than to anything about the housing body. That is the first thing to understand, because two housings can both be ten inch and take completely different cartridges depending on their diameter.
Standard width against big diameter
A standard ten inch housing takes a slim cartridge a little under three inches across. A big diameter housing, usually sold as big blue, takes the same length in a much wider body around four and a half inches across. They are not interchangeable in either direction: a slim cartridge in a wide housing lets water bypass around it entirely, which looks like a working filter and filters nothing. Measure the cartridge diameter, not the housing, since housings vary in wall thickness and outward appearance.
Why the wide one is usually right for a house
A big diameter cartridge holds several times the media of a slim one in the same length, and that has two consequences that both matter on a whole house feed. Pressure drop is much lower at the same flow, so the house does not lose noticeable pressure through the filter. And the service interval is much longer, because there is far more capacity to fill before it blinds. Slim housings suit point of use duties, appliance feeds and pre filtration for a reverse osmosis unit, where flow is modest.
Ports, threads and what will actually connect
Port size is quoted separately from housing size and it constrains the system independently. A big diameter housing fitted with small ports throttles the supply regardless of the cartridge inside it, so match ports to the service line rather than accepting whatever the cheapest version offers. Threads are usually national pipe thread on domestic housings, but check before ordering fittings. Some housings include a pressure release button on the cap, which is worth having, since it saves fighting a vacuum every time the sump comes off.
Fitting so it can be serviced
Leave clearance below the housing equal to the sump depth, or the cartridge cannot be withdrawn without cutting pipework, and this is the mistake that turns a five minute cartridge change into an afternoon. Mount the bracket to a solid surface rather than letting the housing hang on the plumbing. Fit isolation valves either side. Keep the spanner supplied with the housing somewhere you will find it, since the sump is not usually removable by hand once it has been pressurized. Our housing replacement guide covers retrofitting.
Questions people ask about 10 inch water filter housing
What does the ten inch refer to?
The cartridge length, not the housing body. Housings of the same length come in two widths that take completely different cartridges.
Can a slim cartridge go in a big blue housing?
No. Water bypasses around it and passes unfiltered, which looks like a working system. Match the cartridge diameter, not the length alone.
Which width should I use on a whole house feed?
Big diameter. It holds far more media, so pressure drop is much lower and the service interval much longer than a slim housing.
What clearance does it need?
At least the sump depth below the housing, or the cartridge cannot be withdrawn without cutting into the pipework.