See: http://www.musikaktionen.de/en/open-air/h2orchestra/ for more info

The H2Orchestra is a hands-on musical activity for up to 50 people aged 2 and up. Its communicative process of water music composition brings together people of all ages, encouraging multigenerational dialogue. The H2Orchestra consists of more than 50 instruments in 25 tubs plus mechanical apparatuses that make water sounds or use water to produce sound.

Some of the instruments are housed in metal sculptures created by art apparatus craftsman Stefan Schilling.

As players explore them side by side and across from each other, the collection of instruments encourages cooperative sound experimentation and musical interaction.

Number of participants: Up to 50
Age group: Ages 2 and up
Installation: In a circle with a diameter of 8 or 15 meters, or along a 40 meter-long stretch
Venue: Field, pavement, street (asphalt or cobblestone) or waterside
Water required: Approx. 1500 liters; 50-meter hose provided
Transportation: VW T5 Bus
Setup / take-down time: Approx. 1 hour each

See: http://www.musikaktionen.de/en/open-air/h2orchestra/ for more info