Someone near you doesn’t have access to clean drinking water. Provide that person with the means to access clean water without purchasing bottled water (this might be by giving the person a filter, or a solar tea kettle, or something like that). If no one near you needs clean drinking water, we have something called the all-powerful Interwebs. You can buy a family clean drinking water for a year: http://lifestraw.eartheasy.com/products/lifestraw-carbon-credits. If no one lives near you and/or you don’t have funds to buy clean drinking water for someone, find another way to promote access to clean, safe water.