The United States Geological Survey estimates that (as of 2005, the most recent year for which data is available) we withdraw 410 billion gallons of water a day, including both fresh and saline water. Most (80%) of these withdrawals go to thermoelectric power plants (for cooling) and agriculture (for watering crops).
Level 4 is the hair color level that is represented as dark brown. It is one of the most common natural hair colors and also very commonly found in hair dye. Level 4 is also common in red or...
This could be tested by using litmus paper to gauge the pH level of these salon products, and comparing the pH levels with the established natural level of 5 for hair. (Hair and skin actually have a pH that ranges from 4.5 to 5.5, and is typically averaged to 5.0.) You could test a number of salon products (shampoos and conditioners) and a number of store brand versions.