The complete guide
The Buyer's Guide to Whole House Water Filters
The problem this solves
Water in the UK travels a long way before it reaches your kitchen. It leaves a treatment works, runs through mains that may be decades old, turns into your street and then into your property. Along that journey it can pick up sand, rust flakes and silt, especially in areas where the pipework is older or where work has recently been done nearby. Chlorine is used in treatment, and plenty of people notice the taste and the smell of it, most of all in a cold glass of water or the first cup of tea in the morning.
You can deal with that in two places. One is at every single outlet, with jug filters, tap fittings and separate units under the sink. The other is at the point where the water comes into the house, before it branches off. That second approach is what a whole house water filter does, and it is the reason people look for one. You treat the supply once, and everything downstream draws from the same filtered line.
How a three stage water filter system works
This unit holds three cartridges in one housing block, and the water passes through them in order.
Stage one is an FCPS5 sediment cartridge rated at 5 micron. This is the rough work. It is there for sand, rust and silt carried along in the flow. Putting it first is deliberate, because those particles would otherwise clog the finer media behind it and shorten its working life.
Stage two is an FCCBL-S silver series activated carbon block cartridge. Carbon block is a compressed solid rather than loose granules, so the water moves through it slowly and makes good contact with the media. This is the stage designed to reduce chlorine taste and odour, which is the change most households notice first.
Stage three is an FCCST2 cartridge built around ion exchange based resin. It acts on the calcium and magnesium content of the feed water as that water passes through. It sits last in the sequence, after the coarse and the taste stages have done their jobs.
Three bacteriostatic centring discs come with the kit and sit inside the housings to keep the cartridges positioned correctly. A housing wrench is also supplied, which you will want at every cartridge change.
None of this needs electricity. The power source is listed as non electric, so the whole thing runs on the pressure already in your mains. There is no pump, no plug and nothing extra on your bill.
Who it suits
A mains water filter at the point of entry makes most sense in a few situations. Older properties on older street mains, where sediment turns up in the aerators on taps, are an obvious one. So are households where someone finds the chlorine taste off-putting and is tired of refilling jugs. It also suits people who would rather maintain one unit than five separate ones scattered round the house.
It is less useful if you only care about one tap. If the kitchen cold tap is your sole concern, a smaller point of use unit is a simpler job and a cheaper one. The point of entry approach pays off when you want the filtered supply everywhere rather than in one spot.
One thing to be clear about. This filter is for use with drinkable mains (town) water. If you are on a private well or borehole, that is a different situation that needs a proper assessment of your source.
How to choose and what to check before you buy
Start with space. The assembled unit is about 36 cm long, 14 cm wide and 39 cm high. That is the unit itself, and it is not the number that catches people out. What catches people out is clearance underneath. When you change cartridges, the bowls have to come down off the housing, so you need working room below as well as the footprint on the wall. Measure that gap before anything is fixed in place.
Next, look at the location. The lower temperature range is 2 degrees Celsius and the upper rating is 40 degrees Celsius, so you want somewhere that will not freeze and will not get hot. Garages, utility rooms, cellars and under-stairs cupboards are the usual spots, provided the mains comes in there and you can reach it.
Then check the figures. Operating pressure is given as 6 bar, and the maximum supported TDS is 1000 ppm. Your water supplier can usually tell you the typical values for your area, and your plumber can measure the pressure on site.
The maker states that the filter housing is WRAS approved. That is worth noting once and then leaving there. Beyond that single statement, we do not make claims about standards.
Finally, and this is the part worth repeating, a qualified plumber must install it. This unit is cut into the incoming mains. A plumber will size the connections, fit isolation valves either side so you can change cartridges without shutting off the whole house, and test the joints under pressure before handing it back to you. Treat the installation cost as part of the overall budget rather than an afterthought.
Living with it
Day to day, there is nothing to do. The filter sits there and the water goes through it. The only real task is cartridge replacement, and that happens on the maker's schedule set out in the documentation that comes with the unit.
Change them sooner if the flow at your taps starts dropping away. A sediment cartridge loads up with particles over time, and restricted flow is usually the first thing you notice. How quickly that happens depends on the water in your area, so two households with the same unit can have quite different change intervals.
The change itself is simple once you have done it once. Shut off the supply, let the pressure out, use the supplied wrench to unscrew the bowls, swap the cartridges, make sure each O-ring sits flat in its groove, then screw everything back up. Turn the water on slowly rather than all at once, and look at every joint for a minute or two before you walk away. Keeping a spare set of cartridges in the cupboard turns the job into a ten minute task instead of a wait for a delivery.
Give the empty housings a rinse with clean water while they are off. It takes seconds and keeps the inside of the bowls tidy for the next set.
The short version
A whole house water filter treats your mains supply at the point it enters the property, so every tap in the house runs from the same filtered line. This three stage water filter system uses a 5 micron sediment cartridge for sand, rust and silt, an activated carbon block cartridge designed to reduce chlorine taste and odour, and a resin-based cartridge that acts on the mineral content of the feed water. It needs no power, runs at 6 bar, and measures about 36 by 14 by 39 cm.
Two things decide whether it works for you. First, do you have the space at your mains entry point, including clearance below the housings for cartridge changes. Second, are you happy to book a qualified plumber, because this is a mains plumbing job and not a DIY one. Get both of those sorted and the rest is just swapping cartridges on schedule.