By Ian Simpson Jan 15 (Reuters) - West Virginia's top law enforcement officer on Wednesday vowed a full investigation of a chemical spill that contaminated tap water for hundreds of thousands of people. Attorney General Patrick Morrisey said there was a lot of speculation surrounding the spill into the Elk River at Charleston, the state capital, on Thursday that shut off water to more than 300,000 people. "We had an absolute unmitigated disaster here for six days now where people are without water. This is not only utterly unacceptable. It's outrageous on every level," Morrisey told CNN. He said that his investigation would be designed to ensure that another such spill never happened again, and local, state and federal officials all shared responsibility. "We're going to look under the hood, we're going to uncover all the rocks and we're going to let the sunlight in," Morrisey said. The U.S. Chemical Safety Board and the U.S. Attorney for the Southern District of West Virginia also are investigating the leak of about 7,500 gallons (28,000 liters) of 4-methylcyclohexane methanol, or crude MCHM, into the river. About 52,000 water customers have been cleared to drink or wash with tap water as of Wednesday, according to a statement by West Virginia American Water. Officials have said it might be several days before the entire system, with its hundreds of miles (km) of pipe, is safe to use. Officials ordered water use halted for everything but flushing toilets after the leak from a storage tank owned by Freedom Industries, a maker of specialty chemicals. The Freedom Industries site has not been inspected since 1991 and is about a mile (1.6 km) upstream from a West Virginia American Water plant, the biggest in the state. Crude MCHM is used in washing coal and Freedom Industries has apologized for the incident. Downstream from the spill, the Northern Kentucky Water District and the Greater Cincinnati Water Works have shut their intakes on the Ohio River as a precaution, the companies said in separate statements. The chemical is at much lower concentrations than it was in West Virginia and is expected to reach the Cincinnati area on Wednesday morning, the Northern Kentucky Water District said. Water tainted by crude MCHM smells faintly of licorice. Contact with the water can cause nausea, vomiting, dizziness, diarrhea, rashes and reddened skin. West Virginia American Water is a unit of American Water Works Co Inc.