Current methods for monitoring chloride in steam condensate in thermal power plants cannot measure the recommended target level (2 ppb) or are too complex and maintenance intensive for smaller plants. We propose a new relatively low-cost, easy-to-use, low-maintenance method, in which chloride in steam condensate is separated and concentrated with reverse osmosis membranes and the chloride in the concentrate stream is measured using an ion-selective electrode. This concentration-and-measurement system was demonstrated to accurately and quickly detect changes in chloride levels in steam condensate at operationally relevant levels (2-10 ppb) and as low as 0.6 ppb.