Drink up, there are thirsty children in Africa

Volvic's latest sales promotion employs an interesting approach to the psychology of selling. As you prepare to slake your thirst with a litre of France's finest H2O, your eye is caught by the label that tells of the chance to turn this into a 10 litre drink for people in Africa. For every litre of Volvic sold, Danone is committed to delivering 10 litres via various well-creation schemes in Mali, Ghana, Malawi and Zambia. So you can offset your guilt about the amount of landfill your plastic water bottles create with the knowledge you are helping the needy in Africa.

Maybe it's just me, but there seems something ridiculously mercenary about this whole scheme. By combining the two events (water sales in Europe, water supply in Africa) in such a precise ratio, it has the unintended consequence of making them appear to be linked as cause and effect. The proposition 'if you drink our water, we'll pay for water for Africa' begs the question: "what happens if we don't drink enough"? Will the wells run dry across the savanna if we stop sticking away litres of spring water? Drink faster everyone, the summer is coming.

It also is to misunderstand an important sales technique: the reciprocity principle. Humans are hard-wired to understand reciprocity as the basis for social organisation - you scratch my back and I'll scratch yours. Numerous successful sales techniques are built upon the idea that giving something to a customer makes them far more likely to buy something from you. But your chances of doing this successfully are multiplied if you do the giving first - it puts the obligation onto the customer, even if no formal arrangement exists. If it didn't work, companies wouldn't bother giving away free gifts, trial packs, BOGOFs, discounts and prize draws.

Returning to our thirsty Africans, Volvic are expressing this the wrong way around - putting the onus upon us to act, before they will fulfill their side of the bargain. Of course the small print reveals that they are not that callous: they have actually already committed to paying for kit that will deliver 2 billion litres of water regardless of my consumption. But to make the promotion pay, they feel the need to link this provision directly to sales, which is not just an error of PR judgement, but one that will directly impact upon the bottom line.

I'm willing to bet the president of Volvic that he would sell more water if he put the 2 billion figure up front, and let consumers follow with their wallets. I'll let you know what he says.