What is the primary purpose of the large amounts of water used at the launch pad during large launch operations?

Answer

To act as a sound suppression system, absorbing acoustic energy from the engines

Water is used extensively in sound suppression systems to absorb the massive acoustic energy generated by rocket engines, protecting the vehicle and infrastructure, and this effect dissipates relatively quickly near the ground.

What is the primary purpose of the large amounts of water used at the launch pad during large launch operations?
propulsionrocket fuelcombustionemissions