I think part of the answer is that even fairly simple methods seem to prove too much for some people (ref.
boil notices for people in Lancashire recently). I see in Derbyshire the company is providing bottled water while they flush through the system.
Can't realistically see the need for a Sawyer or other filter / purifier at home for the very occasional water outages.
From what was shown on BBC news this morning they are turning up at supermarkets with small trucks of water when as one lady said "it should be an HGV trailer load" to meet demand.
I also think that if some self help instructions were made those that can actually read and follow simple directions, such as those on a microwave meal, would do so and reduce demand for bottled supplies and that in instances like this we should all be mindful of our neighbours/relatives that might find it a struggle.
While residing on Crete we would get water supply cut off for several days at a time, the water came directly from the holes drilled into the mountain so was spring water on tap! Never needed a filter and had no additives but the pipe system was prone to failure. After the first time I stored water in the fridge and made cistern from a wine barrel and a ball valve from a w.c. for the shower (jumping into a local pool to wash off a days hard work, dust and grime is really frowned upon
) A water filter, had they been available, would have really helped as there was a stream that ran into the bay. So while having a Sawyer or other filter would not be that helpful in this (chlorine) case they could make available other sources.
As an addendum to my earlier post: an activated charcoal filter will also help remove chlorine.
Rob.