for those with no clean water supply

[Bearwood]

I have personal experience of the Drinksafe Water Bag and I've given it up as a bad job when compared to similar alternatives available. A colleague of mine has the Travel Tap and the Water Straw of which, the former is equally poor (despite videos online which show the contrary) and the water straw is surprisingly suitable for its intended use.

For camps extending to several days, the Drinksafe filters tend to slow down to a drip more than a flow, and the filters become useless unless thoroughly dried out after each use, making them a little unsuitable for field service in my opinion.

I've resorted to the MSR Sweetwater with hand-pumped filter and added diox drops for myself whilst out and about camping/bushcrafting and I rate it very highly, certainly twice the price of a Drinksafe Water Bag, but I wish I'd gone for the MSR first and saved the money. I still have a the Drinksafe somewhere if someone wants to try it?

[Bearwood]

Here you go;

http://www.alloutdoor.co.uk/camelbak-hy ... filter.htm

(No connection to seller etc)

Since I bought mine, the price of it seems to have reduced somewhat, whilst the cost of the Drinksafe has increased. MSR also do a water bag style system, although I have no experience of that, so I can't comment. The advantage of a pumped system such as the Sweetwater, is that it's fairly 'on demand' and not at the mercy of gravity.

[Bearwood]

I'm thinking borehole.

Funnily enough, boreholes (the analysis and construction of) accounts for about 30% of my workload at present. I work as a Geologist for an engineering firm. Costly, as prices for a 20 metre hole in 'soft' strata (gravel/clay/sand/silt) would be in the region of £3k (general Midlands prices) just to drill the hole and install with casing. Pumps can add a fair bit more onto the price.