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water filter

Hi, do you have any experience with water filters? I am looking for a system that filters canal water in two stages. I know about drinking water filters, but I would also like a cruder pre-filter for non-drinking applications like washing machine, shower, etc.

any help welcome.

Asked by: otto  | 1.17pm, Wednesday 18 June

WW says:


I am sure that you know that most drinking water on large ships and commercial vessels is made using reverse osmosis filters- by using high pressure, they pass water through a semi-permeable membrane, which rejects the vast majority of dissolved contaminants. They tend to be quite energy intensive and, if not used continually, usually need special storage solutions for the delicate membranes. They also need a series of pre-filters to remove suspended solids- and these would tend to be blocked quickly by solid-laden water, such as canals. The levels of silt are, usually, much lower in sea water, where these systems operate.

Also, the water, when stored, would need to be treated with chlorine to ensure no microbial activity in the storage tank.

As for lower quality water, it might be possible to use filters that remove sediment, down to 0.5 micron, but they are not designed to take water directly from a canal, etc.

Another point- it might require an abstraction licence to use on inland waterways... I think that the position of this is unclear! This would require discussion with the EA and/or BW.

Is there any particular reason that you want to purify water for consumption aboard, which is not paticularly energy efficient (especially for consumption)? Having seperate systems, such as for hot water, and drinking water, would need asbsolute seperation, to avoid potentially disasterous cross-contamination.

Mark Langley

Mark Langley  | 5.58PM, Wednesday 18 June

Readers say:

thanks for the detailed answer Mark, much appreciated. The reason why I'm looking for such a solution is that I spend a lot of time on moorings (esp. winter moorings) where there is no water available and I spend a lot of time driving back and forth from waterpoints. Also, for a long time I have been dreaming of having a washing machine on board, but that would exhaust my watertanks even faster. So the intuitive answer would be to have a system on board with several inline filters, where I could branch off water for various usages. So, for the washing machine, it would only need a crude filter, for showering and washing up more refined, and for drinking a state of the art filter. Another benefit would be that I could loose the water tank, which would free up storage space.

otto  | 3.55PM, Thursday 19 June

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