As I start to plan more carefully the Thames Source Quest (TSQ), I'm wondering what approach to take in terms of support. Interesting definitions of 'unsupported' are provided on [1] and Fastest Known Time [2]. The main disagreement seems to be related to water supply.

This really means no external support at all from any human being and therefore carrying all the supplies the whole way, except what can be obtained from natural sources. Water should only be obtained from natural sources according to [2], but could be supplied externally according to [1]. That said, the definition of a 'natural source' of water is not as obvious as it seems. If a spring in the mountains is natural and a free tap next to a river lock is not, what about a pipe draining the water out of a spring? I would say natural, but I can understand some would disagree. Food could potentially be harvested from natural sources too [1].
[1] prohibits the usage of phone calls, but surprisingly reckons that being offered a shelter and water is acceptable. The position of [1] here lacks a bit of coherence and seems biased towards classifying the Marathon des Sables as unsupported, which I cannot agree with. With all due respect to the toughness of this race, I can hardly consider unsupported an event where tents, water and medical crew are waiting for you every night.
Furthermore, a valid issue pointed out by [1] is how to react to local by-passers offering water, food, shelter or whatever else. It would be rude to refuse...

This means that no support team is following the runner. However, it is possible to grab whatever is on the way, including buying in stores or hide supplies in advance [2] (as at least one team did during the PTL last year). This is what I've done (for the water only) during my solo London to Brighton run, and this is also the spirit of the PTL. Because nothing is black and white, [1] also differentiates between several forms of self-support, the most permissive one including a crew following loosely the runner. I'm not too interested in that, so I won't discuss it in more details.

A team is following the runner the whole way to provide food, drink, spare clothing and all other needs.

As a summary, I would consider 'unsupported' the following:
  • Water can be obtained from natural sources only, like [2].
  • Food must be carried or obtained from natural sources only, like [1].
  • Shelter must be carried (tent) or natural shelters must be used.
  • Phone calls are prohibited as they offer mental support, but sending out SMS about your progress is acceptable... as long as you don't read the answers :) .
In one sentence: take everything you want from the nature and give back everything you want to whomever you want. Now, this is only my definition. I'm not saying I'm going to run the TSQ unsupported as yet :) .

Open for debate.

Ultra unsupported