Calcium Carbonate Saturation Index (LI: Langelier Index), an indicator of CaCO3(s) saturation, indicates corrosiveness of drinking water and it has been used to monitor drinking water conditions in USA, E.U, and Japan. The objective of this research was to measure LI parameters including water temperature, pH, total alkalinity, calcium ion concentration, and electric conductivity, and to evaluate possibility of using LI in domestic system. Results showed that water temperature varied from 2.0 to 26 ℃ during 15 months, indicating an average annual temperature of 23.9℃. Total alkalinity was from 20 to 26 ℃ during 15 months, indicating an average annual temperature of 23.9℃. Total alkalinity was from 20 to 45 mg/L. The concentration difference between total alkalinity and HCO3- value was hardly observed; the concentration of total alkalinity can be replaced by that of HCO3- Tap water had a medium corrosiveness since LI values were from 2.0 to 0.5. To reduce the corrosiveness and to increase LI values of drinking water, the results of this study showed that chemicals such as Ca(OH)2, CaCO3, NaOH, or NaHCO3 should be added to water treatment plants.

탄산칼슘 포화지수(LI: Langelier Index)는 탄산칼슘의 포화정도로서 수돗물의 부식성을 나타내며 수도관 부식방지를 위해 미국, 유럽, 일본 등은 수도법에 의해 관리되고 있지만 국내는 아직 도입되지 않았다. 본 연구는 LI의 국내 도입 타당성을 검토하기 위해 LI인자(5개항목: 수온, pH, 총알칼리도, 칼슘이온, 전기전도도)들을 측정하고 LI값을 산출하였다. 수온은 연간 2.0~26 ℃, 연평균 23.9 ℃로 나타났다. 총알칼리도는 30 mg/L (as CaCO3)로 나타났으며, 총알칼리도를 HCO3- 농도 값으로 대체가능성을 검토한 결과 농도 차가 거의 없는 것으로 나타났다. LI값은 2.0~-0.5로 나타나 부식성을 가지고 있는 것으로 나타났으며, 수돗물 부식성을 감소시키기 위해 정수장에서 Ca(OH)2 CaCO3, NaOH, NaHCO3 등을 투입할 필요가 있는 것으로 나타났다.