“Joining” in this context has multiple meanings. Sold as reusable water bottles, with the proceeds benefiting the construction of third-world water pipelines, they can be literally “joined” to interconnect like pipes, forming a metaphorical water pipeline. And by purchasing a bottle, supporters are “joining” the cause in the social-media/cause-marketing sense of the word.
Our plastic bottles should be kept for life, each bottle has a bayonet system in the top and bottom, they can be connected to one another so you can get the idea of building the pipeline at home.
The bottles have a double lid opening for easy washing and a rubber band for attaching to clothing, bikes, bags or fingers!
(See also: Elizabeth Royte on Packaged Water)