Taiwan Water Corporation (TWC) , which provides water to 22 cities and counties across the country, said Sunday that as of late last year it had achieved a penetration rate of 90.7 percent on average. The current average water supply penetration rate of over 90 percent is much higher than the average 42.66 percent posted in 1974, when the company was established, a spokesman for the state-run TWC said. According to TWC statistics, the highest penetration rate was in Tainan City in southern Taiwan, with 99.88 percent of its households on tap. Chiayi City was second, with 99.66 percent of its residences supplied by the company. A rate of over 90 percent was recorded for other 12 cities and counties, including Taipei, Yilan and Taoyuan counties as well as Keelung and Hsinchu cities in the north. The others included Changhua and Yunlin counties, Taichung City in central Taiwan, Tainan County, Kaohsiung City, Kaohsiung County in the south and the offshore Penghu County. The lowest penetration rate -- 45.13 percent -- was in Pingtung County on Taiwan's southernmost tip, which is one of the key issues that county authorities are waiting to have resolved. TWC supplies water to 22 cities and counties on Taiwan proper and on the offshore counties, including Penghu. It serves some 17.3 million people, but its service does not cover the capital of Taipei City or some areas of the adjoining Taipei County. 