Is a whole house water filter the same as a water softener?

No. A whole house filter removes chlorine, sediment and, on multi-stage systems, metals and bacteria from all the water entering your home, but it does not reduce hardness or stop limescale. A water softener does the opposite. If limescale is your problem, check the hardness at your postcode and read the softener guides instead.

Do whole house filters reduce water pressure?

Not noticeably when sized correctly. Compare the rated flow in litres per minute with your household's peak draw: a one or two bathroom home is usually covered by 25 L/min, which is what the BWT E1 is rated at. Larger 20-inch housings lose less pressure than 10-inch ones.

Can I install a whole house filter myself?

It is a cut-and-fit job on the incoming main, with isolation valves either side and a bypass loop, so most people use a plumber. Expect £150 to £300 for a straightforward fitting on top of the unit price.

Whole House Filters

Installed at the mains inlet, these systems filter every drop of water entering your home.

Best for: Homeowners wanting filtered water from every tap and shower · £250–£499

Read our full guide: Best Whole House Water Filter UK

A whole house water filter, also sold as a mains water filter or point-of-entry filter, sits on the pipe where water enters your home and treats everything downstream: kitchen tap, showers, bath, washing machine and boiler. Depending on the stages inside, it removes chlorine taste and smell, grit and rust from old mains, and on multi-stage systems bacteria, lead, nitrates and other metals.

It is not a water softener. A filter takes chlorine and particles out but leaves the calcium and magnesium that cause limescale, so if furred-up kettles and scaled shower screens are your problem you need a softener, not one of the systems below. Our full guide explains who in the UK benefits, how to size one by flow rate, what fitting and cartridges cost, and why neither system here is certified for PFAS.

Not sure which to pick? Check your water first.

Osmio PRO-III Ultimate Whole House

Whole House · NSF/ANSI 42, NSF/ANSI 61, WaterMark

Why it fits: The only whole-house unit here that also targets bacteria, nitrates and pharmaceutical residues
NSF/ANSI 42 and 61 certified via IAPMO, with WaterMark approval as well
Ceramic stage runs three years, so most years need only a carbon change
What it won't do: Does not touch limescale, so hard-water homes still need a separate softener

Typical price

£499approx.

Check current price at Osmio

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BWT E1 Single Lever

Whole House · WRAS approved

Why it fits: WRAS approved — meets UK plumbing standards
Single-lever backwash makes maintenance straightforward
Protects boilers and appliances from sediment damage
What it won't do: Only removes sediment and particles — not heavy metals or PFAS

Typical price

£250approx.

Check current price on Amazon

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Side-by-side comparison

Filter	Price	Rating	Chlorine	Lead	Bacteria	Sediment	Nitrates	Heavy metals	Hormones	Pharmaceutical residues	Annual Cost
Osmio PRO-III Ultimate Whole House (opens in new tab) Whole-house treatment where bacteria and heavy metals matter more than limescale	£499	4.4									£188/yr
BWT E1 Single Lever (opens in new tab) Protecting whole-house plumbing from sediment and particles	£250	4.3									—

Common questions

Is a whole house water filter the same as a water softener?: No. A whole house filter removes chlorine, sediment and, on multi-stage systems, metals and bacteria from all the water entering your home, but it does not reduce hardness or stop limescale. A water softener does the opposite. If limescale is your problem, check the hardness at your postcode and read the softener guides instead.
Do whole house filters reduce water pressure?: Not noticeably when sized correctly. Compare the rated flow in litres per minute with your household's peak draw: a one or two bathroom home is usually covered by 25 L/min, which is what the BWT E1 is rated at. Larger 20-inch housings lose less pressure than 10-inch ones.
Can I install a whole house filter myself?: It is a cut-and-fit job on the incoming main, with isolation valves either side and a bypass loop, so most people use a plumber. Expect £150 to £300 for a straightforward fitting on top of the unit price.

We may earn a commission when you buy through our links, at no extra cost to you. Recommendations are based on water quality data, not sponsorship. Affiliate disclosure