But it's a bit late to be telling us to carry a bottle of water when we're standing on a platform or boarding a train. There are no bottles of water to be had. Passengers can't suddenly carry a bottle of water if none are available.
So TfL boffins have been busy these last few weeks with a new project to bring soaring temperatures down. They've created a new brand of bottled water, called Underground Water. And they're going to start distributing it at stations today.
Underground Water is a whole new approach to the battle against soaring subterranean temperatures. Now you can carry a bottle of water with you at all times, whether you've remembered to buy one in advance or not. No longer need your tube train* feel like a mobile sauna, because you can guarantee ice cold Underground Water will cool you down. * Underground Water will also be provided for travellers on the New Bus For London. Please note that this is a special promotional offer to support the launch of this great vehicle, and absolutely not an admission that the air cooling system doesn't work and conditions aboard are hell on wheels.
Underground Water will be sold at station ticket offices* across the network. Just go up to the ticket office window and ask the member of staff for a bottle of Underground Water. From this morning they'll have unlimited stocks to supply. * If you're unfortunate enough to be at a station whose ticket office has closed, or is only open for a few hours a day and has now shut, don't worry. Listen out for the "In this hot weather, always carry a bottle of water with you" message being played out over the station loudspeakers. At this precise moment a member of station staff will appear with a tray of bottles of Underground Water and they'll be happy to hand one over. It'll be a bit like the interval at the cinema with the usherette and the ice creams, for those of you old enough to remember this. TfL wants all of its station staff to be more customer-facing, and the launch of Underground Water is an excellent way to ensure that they are.
Each 500ml bottle of Underground Water will cost £1*. * Whilst it would be nice to hand out bottles for free, this is not an acceptable option in a time of austerity. If you want something cheaper, bring your own.
* Oyster pay-as-you-go users will be able to touch in for a bottle at the reduced price of 80p. Emirates Air Line users will be asked to pay £3.20, in line with the existing surcharge for aerial travel.
Underground Water will be available in ten exciting sugar-free vitamin-enhanced flavours, according to which line you are travelling on*. * Please note: all trains on the Metropolitan line are fully air-conditioned, so there is no blackcurrant flavour.
* Please note: all trains on the London Overground are fully air-conditioned, so there is no tangerine flavour.
Stamford Brook: Tropical lime Caledonian Road: Highland spring water Bayswater: Sparkling lemon Chig Well: Spa water with a hint of orange Stock Well: Blueberry and soda Canada Water: With a dash of maple syrup Barbican: Alcohol-free water Cutty Sark: Iced tea London Bridge: Slightly murky with floating bits Waterloo: Bog standard still water
All Underground Water bottles are fully recyclable and should be disposed of in the bins provided. * TfL does not encourage the wanton destruction of our planet through the pointless purchase of bottled water when quite frankly tap water in a reusable canister would cool you down just as much without accruing unnecessary carbon debt.
Londoners, why not grab a bottle of Underground Water on your tube journey today? And as a special introductory offer, all bottles are free today before 12 noon. So don't forget to go up to the ticket office at your local station this morning and ask for a free bottle of Underground Water to keep you cool. Because, in this hot weather, you should always* carry a bottle of Underground Water with you. * While stocks last.