World Water Monitoring Day 2026: Observed Annually on September 18

Key facts

• World Water Monitoring Day is observed annually on September 18, which falls on a Friday in 2026.
• The observance was started in 2003 by Roberta Savage, president of America's Clean Water Foundation, to put simple water testing kits into ordinary hands.
• The original date of October 18 was chosen to align with the anniversary of the 1972 Clean Water Act, but was moved to September 18 in 2007 because water bodies freeze in cold-climate countries before October.
• The Water Environment Federation and the International Water Association took over coordination of the program in 2006, aiming for one million participants across a hundred countries.
• In 2015, management passed to EarthEcho International, a Washington, D.C.-based nonprofit founded by the children of oceanographer Philippe Cousteau, initially named the Philippe Cousteau Foundation before a rebrand over a dispute about the Cousteau family name.
• Under EarthEcho International, the day expanded into the EarthEcho Water Challenge, with testing encouraged anytime between March and December.
• Standard testing kits measure four basic indicators: temperature, clarity, dissolved oxygen, and acidity.