In recent years the changes in rainfall between dry and rainy seasons in Taiwan have come increasingly extreme, resulting in an increased risk of both droughts and floods. TSMC explains a number of its fabs have achieved a process water-recycling rate in excess of 90 percent, and notes its total process water recycling rate reached 86.5 percent in 2012. UMC's total water recycling rate is quite a bit lower though, the firm quotes a figure of 60-70 percent but notes its newer 12-inch fabs incorporate better green-building technologies.
Rainfall in Taiwan is at the lowest level since 1947, according to the government’s Water Resources Agency, which in November last year started restrictions on water use in two parts of the island where most of the fabs run by TSMC and UMC are located. If conditions worsen, as is likely this year, a new round of tighter restrictions will limit water supplies for industrial and public use.
Still, TSMC and UMC, which account for more than half of the world’s foundry production for customers such as Apple and Qualcomm, have taken steps to increase their water reuse after drought conditions in Taiwan became an issue for chipmakers more than a decade ago.