Under-sink water filter installation in London
Getting an under-sink drinking water filter fitted in London — what it costs, whether you could do it yourself, and where the job stops being DIY.
Very hard
Thames Water, Affinity Water, SES Water, Essex & Suffolk Water
Water in London
- London sits on the largest area of very hard water in the UK. Almost the entire city is supplied from chalk aquifers and the Thames, and hardness typically runs between 250 and 330 mg/l CaCO₃.
- Water in London is supplied by more than one company. Thames Water covers most of it, Affinity Water serves large parts of north and west London, SES Water covers the southern fringe and Essex & Suffolk serves some eastern boroughs — so neighbouring streets can be on different suppliers.
- The city's housing stock skews old, and Victorian and Edwardian properties frequently have pipework that has been altered several times. Installers here quote more cautiously than in newer areas for exactly that reason.
- Flats are the dominant property type in inner London, and that shapes what is actually installable: no drain access and no space near the stopcock rules out a conventional softener in a great many properties, which pushes demand towards scale inhibitors and under-sink filtration.
- Softener demand per household is among the highest in the country, and there is a correspondingly deep pool of installers who fit them routinely rather than occasionally.
You have very hard water — among the hardest in the UK.
Limescale will be a constant in your home and a real cost in appliance life. A water softener is genuinely worth the investment here and most households who fit one notice the difference within days. At the very least, protect the boiler.
Who supplies London
Water company boundaries do not follow council boundaries. Check your postcode for the supplier at your address.