Water filtration

Three different problems

The important point is that none of these are the same problem. A softener will not improve the taste of chlorinated water, and a carbon filter will not stop your kettle furring up. Getting this the wrong way round is how people end up disappointed with an expensive installation.

What we fit

Under-sink cartridge filtration with a dedicated tap

The most common and, for most households, the most sensible. A filter cartridge under the sink feeds a separate small tap on the worktop, so filtered water is available for drinking and cooking while the main tap remains unfiltered for washing up. Carbon cartridges deal with chlorine taste and odour and improve taste noticeably; combined sediment-and-carbon cartridges handle both.

The dedicated tap approach works well alongside a softener too, because the hard tap that the regulations require can be the filtered one – unsoftened, but pleasant to drink.

Three-way and four-way taps

A single tap giving hot, cold and filtered from one spout. Neater than a separate tap and the usual choice where the kitchen has been designed rather than accumulated. Worth knowing that they are more expensive to replace and the cartridges are sometimes proprietary.

Whole-house sediment filtration

Appropriate where there is a genuine particulate problem – typically a private supply, a borehole, or an older property with corroding steel pipework. Not usually necessary on a mains supply, and it needs a filter housing somebody will actually service.

Reverse osmosis

Removes almost everything, including minerals. It is the right answer for specific contamination concerns and for aquariums and certain appliances. It is slow, it wastes water to drain, and it needs a storage tank and space. For a household whose complaint is ‘the water tastes of chlorine’, it is considerably more than the problem requires.

Private supplies

Parts of rural Norfolk are on boreholes and private wells rather than mains water, and that is a different situation entirely. A private supply has no water company monitoring it, and treatment should follow a test rather than a guess – what the supply actually contains determines whether you need sediment filtration, UV disinfection, iron and manganese removal, pH correction or some combination.

The right sequence is: test first, at an accredited laboratory, then specify treatment against the results. Fitting a carbon filter to a private supply with a bacteriological problem is worse than useless, because it feels like you have done something. Local authorities have duties around private water supplies and are generally a good first call.

Maintenance, which is the whole game

Every filter is a consumable, and an exhausted filter is not neutral – it is worse than no filter. Carbon that has stopped adsorbing can begin releasing what it captured, and a sediment cartridge that has blinded off restricts flow and becomes a place for bacteria to grow.

• Change cartridges on the manufacturer’s schedule, by date rather than by whether the water still tastes fine. Taste is a poor indicator of filter exhaustion.
• Fit isolation valves so cartridge changes do not involve draining the kitchen.
• Sanitise the housing at cartridge changes on any filter that will sit unused for periods.
• Keep the filter out of direct light and heat, which encourages growth in the housing.
• Do not filter water that then sits in a long dead leg – stagnant filtered water is a worse proposition than moving unfiltered water.