For their long-term travel in the UK, my grandparents are staying in older hotels where staff have warned them to boil and filter tap water before drinking. The difficulty is that each of their rooms (so far) contain only 2 water sources ─ 1 showerhead and 1 set of separated taps as follows ─ but the red space between the taps is always too narrow and tiny to support anything, much less a water filter.

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They will boil the water with their kettle to kill antigens ─ thus the water filter does NOT need to do this. But what removeable water filter can they use to filter out 1-4 and 6 underneath, because pitcher filters cannot do so?

  1. Toxic metals (Lead, Mercury, Aluminium, Cadmium, Chromium, Copper, etc.)
  2. Additives (Chlorine, Chloramines, Fluoride) Chlorination
  3. By-Products (Trihalomethanes or THMs)
  4. VOCs and other Organic Compounds (Pesticides, Herbicides, Pharmaceuticals, Fuels)
  5. Bacteria and viruses (Giardia, Cryptosporidium, etc.)
  • @Fiksdal Uh no, this is not a duplicate. That other question seems to require the filter to filter out pathogens? My question does not require it ─ I require only filtering of non-living metals and substances.
    – user13759
    Sep 26, 2016 at 18:18
  • @pnuts Well, they can always go buy bottled water without staff's giving it to them. But bottled water can be unsafe and harms the environment. Thus my grandparents prefer water filters.
    – user13759
    Sep 26, 2016 at 18:20
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    Is there reason to believe there are radioactive substances in the water? The local water agency should produce some kind of report of test results that would tell you if this is a problem. If the pipes in your hotel are made out of uranium, you have far bigger issues. Sep 26, 2016 at 18:34
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    In all honesty, as they are your parents (so I guess you somehow care for them) I'd suggest you to see things from a different point of view... Really, honestly, "hotels where staff have warned them to boil and filter tap water before drinking" to me sounds just one simple thing: run away, water is probably the least of their problems. That said, on a more general note, your parent can find tons of the world safest filters for personal use in most of the stores around: bottled water.
    – motoDrizzt
    Sep 26, 2016 at 21:35
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    2. If there's chlorine in the water that you want to remove then bacteria are already taken care of (unless you filter the water free of chlorine and then leave it sitting around for a while)
    – CMaster
    Sep 27, 2016 at 10:52

2 Answers 2


I wholly agree with the other answer which says that you could just get quality tap water from the staff or something like that.

However, for this answer I'm doing something I often do, which is accept the premise of the question itself, which says "I want a device to remove the following substances from water." I am assuming (wrongly or rightly) that is a justified premise, and answering that.

Considering the substances that need to be removed, I'd say that this can not be accomplished by simple filters. As references for this statement, see answer 1 and answer 2.

You need either a distiller or reverse osmosis.

Incidentally, both these methods also remove pathogens, so there will be no need to additionally boil the water.

Reverse osmosis accomplishes this by pumping water through a membrane with very tiny holes. A good RO system removes everything you are talking about in the question. Here's another answer in which I mention an RO system that is portable and can be connected to the tap through a hose, eliminating the space concerns.

You mention chlorine in OP. Please note that the higher the chlorine level, the more of a strain it will be on the membrane of the RO system. (For normal, municipal water chlorine levels, it's not a problem, though.) But the higher the levels of chlorine, the more often the membrane will have to be replaced.

Distillation works by creating steam and collecting the steam as water. Since none of the chemicals or pathogens you mention will evaporate in the steam, they will be eliminated in the distillation process. Here's a related answer in which I describe distillation in further detail. With most distillers, you manually pour the water into the distiller using a jug or something like that. Thus, the space is not a problem there either.

Please note that distillation is quite energy inefficient compared to RO. It uses a relatively high amount of electricity, whereas RO does not.


Mains water in the UK is safe to drink. Rather than an amateur attempt to purify water that's been through some ancient plumbing system, the way to get safe drinking water in the UK is to get mains water.

The simplest solution is to buy one or two bottles of water (which should cost less than £1), and after using them ask the hotel staff to fill them from the kitchen or bar tap. Any establishment selling alcoholic drinks is obliged to provide tap water for free, and even if it doesn't have a bar I would expect a hotel to be willing to fill up an empty bottle for you. (Or take the kettle and ask them to fill that.)

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    +1, but the hotel may not be on mains water - I've been to a few oldies which run on ground water pumps, which may possibly include this one. It's hotels like those that stay on the safe side of the law by telling their guests to not drink the water. Alternatively the cold water tap is the mains and it's actually the hot water tap that shouldn't be drunk from (this is why they're often separated in the UK). Sep 26, 2016 at 21:43
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    OK, I guess that's possible in really rural locations. In the case of hotels not on mains water, I still wouldn't attempt to set up my own filtration system. Basically if they're not providing water that the manager is willing to drink then I would buy bottled water.
    – djr
    Sep 26, 2016 at 22:35
  • Groundwater pumps are actually semi-common in London due to the underground city and the relatively high water table through the porous London clay - if all the pumps were turned off, London would be a very different place indeed! (Plus from a management point of view, groundwater is practically free, so it's not particularly hard to find hotels that use groundwater in central London) Sep 26, 2016 at 22:51
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    No one is obliged to provide potable water for free, unless their alcohol premises licence from the council specifies it. This provision is often included for night clubs but rarely for other establishments. I am sure any hotel or hostel would do so, however.
    – Calchas
    Sep 27, 2016 at 17:20
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    @Fiksdal - Sorry, that was an unhelpful Britishism. "Licensed premises" means ones licensed to sell alcohol. So you're right that it's only a requirement for hotels which have a bar or licensed restaurant. I've updated my answer.
    – djr
    Sep 27, 2016 at 21:58

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