The Solomon Islands government says water from Gold Ridge mine's tailings dam is now safe to drink.
The new tailings storage facility releases treated water into the Tinahula River in central Guadalcanal and will reduce the amount of water in the dam after excessive rain.
The recent opening of the facility follows ongoing accusations from communities downstream of the tailings dam that the company is poisoning the river.
The government has given the mining company a six month license to operate the plant, which took seven months and one million US dollars to complete and has undergone six weeks of monitoring and testing as part of its commissioning phase.
In the process, water is treated to strict internationally accepted drinking water standards and the environment minister Bradley Tovosia says the water flowing to downstream communities is now safe.
He also says the water treatment plant will be continually monitored, with daily test samples sent to Australia each week and the results provided directly to the government.