When the water board announced cryptosporidium in the water when we were in St Albans all the shops sold out of water within hours. Come home from work and without stored water you'd go thirsty, except in this case the water was perfectly useable and drinkable, absolutely no need to rush out and buy bottled water. Just needed a rolling boil for 10 mins. ISTR we got a payment for the extra energy that the boiling consumed for the week or two the restriction lasted.