By Terry Gardner, Los Angeles Times

Two Seattle tour companies have launched Travelers Against Plastic to motivate travelers and tour operators to say “no” to disposable plastic water bottles and choose other methods of ensuring their water is safe to drink.

Crooked Trails and Wildland Adventures launched the website, which allows travelers to make a no-plastic-bottle pledge, on March 22. By last week, 136 people and 10 tour operators had signed the pledge.

Eight of 10 single-serving plastic water bottles wind up in landfills, according to the Recycling Institute. About 34.6 billion bottles are emptied annually in the U.S.

Chris Mackay, co-founder of TAP and executive director of Crooked Trails, says her guests are told to be prepared to clean their own water on their travels. In 2008, a guide to Machu Picchu in Peru watched in disbelief, Mackay says, as her group filled their water bottles from a waterfall, then cleaned the water.

Mackay says the surprised guide said, “On behalf of my country, I want to thank you for doing this, because we have plastic water bottles everywhere and along the rivers. You are the first people I’ve seen clean their own water.”

Water is easily cleaned, Mackay says. She likes the Klean Kanteen’s bottle because it has a wide mouth that easily accommodates a SteriPEN. The pen uses UV light (rather than chemicals) to quickly kill 99.9 percent of bacteria, viruses and protozoa that cause water-borne illness.

REI lists a variety of methods for treating water.

For travelers without a good reusable bottle, a custom TAP bottle is available from Kleen Kanteen for $21.95; 25% of the proceeds will be donated to TAP.