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Jug, tap and under-sink water filters
How a UK jug filter, a filter tap and an under-sink unit differ, what the Drinking Water Inspectorate says they are for, and how WRAS approval fits in without a certificate number.
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Tap water in England and Wales is already required to be fit to drink. A filter is a choice about taste, smell or appearance, or about a fault in your own pipes. It is not a health treatment. The Drinking Water Inspectorate says so. This page compares the usual kitchen filters and keeps the shop's words separate from the Inspectorate's.
What DWI says
DWI's page on domestic water filters and softeners says jug filters stand alone and are not connected to the supply, while other devices are plumbed in. It says sellers' claims sometimes worry people. Claims it lists as common include pesticides or taste and odour (activated carbon), minerals (reverse osmosis), colour or particles (a fine filter), hardness (a softener or reverse osmosis) and nitrates (ion exchange).
DWI says the company must supply wholesome water for drinking, cooking and washing, and that extra home treatment is not needed as a health protection measure. A filter for taste or odour should contain activated carbon, and the cartridge must be changed as the maker says or it may leach. Black specks are usually carbon from the filter, not the tap. DWI also mentions a covered glass jug in the fridge as a cheaper step.
Ask the company for the quality report for your address before you buy. How to do that is in water quality and hard water areas.
Two things on the same page are easy to mix up with a carbon cartridge. Reverse osmosis removes most dissolved solids, produces a waste stream, and DWI says the water is not generally considered suitable for drinking and cooking. Installing one must be notified to the water company. We are not linking an RO unit. A softener swaps hardness for sodium and should leave an unsoftened drinking tap. That is a different appliance. See water softeners. Scale on a kettle is hardness. Cleaning it is in limescale.
Jug, tap, under-sink, filter tap
A jug is not plumbed in. It only treats what you pour through it. We did not open a jug listing, so none is linked. A filter on the tap diverts some cold water through a cartridge. An under-sink unit sits in the cupboard and feeds its own tap or a filter tap, so a missed cartridge change is easier to overlook. Connecting it is plumbing on the drinking supply. A filter tap keeps filtered water on a separate path from the hot and cold. A boiling water tap is a different product. Do not assume the cartridges interchange.
The fittings rules, without a certificate number
A plumbed-in filter is a water fitting. Regulation 4 of the Water Supply (Water Fittings) Regulations 1999, as made, says every water fitting must be of an appropriate quality and standard and suitable for the circumstances. The original text we read points to a CE marking, a harmonised standard, a British Standard or equivalent, or a specification approved by the regulator, and it requires workmanlike installation. Check the current text. Scotland and Northern Ireland have their own rules.
DWI says the product must adhere to regulation 4, the supplier should be able to show that, such as through UK certification, and you should use a qualified plumber and check with the water company. It also says not to buy from a door-to-door seller offering to test your water.
WRAS describes approval as one way to demonstrate compliance. That is the general idea. The listings below did not give an approval number in the features we read, so we are not claiming one. If you need it, ask the seller and check the WRAS directory.
What the Wickes listings say
Figures are Wickes's. We have not tested the filters. A line about impurities is the seller's claim, not a result we are adopting. Read DWI before you decide the tap water was unsafe without a cartridge.
We haven't tested this. Figures are as the maker states them (checked 13 November 2026).
BWT inline drinking water filter kit. Wickes says it includes a self-piercing saddle valve, bracket, hoses, a chrome tap and a cartridge, and that it reduces sediment, chlorine, limescale and unpleasant tastes and odours. It states a maximum flow of 2 litres per minute. That is Wickes's figure, and it is modest next to an ordinary kitchen tap. A self-piercing connection is still plumbing.
BWT inline replacement cartridge. Wickes says to replace it every 4 to 6 months, and states the same maximum flow of 2 litres per minute. The interval is the listing's, not a legal rule. DWI's warning still applies if you leave a carbon cartridge in too long.
Abode Puria filter kitchen tap, chrome. Wickes describes a single-lever hot and cold tap, filtered water on a separate channel, and a carbon filter changed with a twist. It states a minimum operating pressure of 1 bar. If the kitchen is gravity-fed and weak, read low water pressure first. The listing also says the filter removes impurities including bacteria, chlorine and microplastics. We have not tested that. DWI says extra treatment is not required as a health protection measure. Treat the sentence as the seller's claim.
Swich round filter handle, chrome, GAC and resin. Wickes says it lets you twist a tap between ordinary cold water and filtered cold water, that it suits a standard 35 mm tap hole, and that the filter is for hard water areas and deals with scale, taste and odour. Dealing with scale at one tap is not a softener on the rising main.
We opened a Carysil under-sink kit and did not link it. The listing claimed it could remove up to 100 contaminants and talked about safer water. That count is not something we could check, and it sits badly beside DWI's statement that home treatment is not needed to make the water safe.
Write the date you fit a cartridge on the housing. A filter that has sat wet in an empty house is the case DWI is warning about.
Do I need a filter to make UK tap water safe?
DWI says no, not as a health protection measure, for a normal public supply in England and Wales. A filter is a preference about taste, or a temporary help with colour from your own pipes. If you think the supply is wrong, contact the water company.
Is an under-sink filter a water softener?
No. A softener treats hardness on the pipes it is connected to, uses salt, and should leave a drinking tap unsoftened. A carbon cartridge is aimed at taste and odour. A line that says a cartridge "deals with scale" is that product's claim.
What does WRAS approval mean on this page?
WRAS says approval is a way of showing a product meets the water fittings regulations. Regulation 4 is the quality rule in the original 1999 text. We are not quoting an approval number, because the features we read did not give one.