Abstract: The world of water services changed significantly over the last two decades, opening it to new business possibilities as promoted by different international financial institutions. Such prospects arose in the face of extraordinary population growth and dire water expansion needs. Accordingly, a vast increase of water-services privatization contracts between foreign investors and states ensued. Today, 10 percent of global consumers receive water from private companies. Inevitably, disputes have emerged regarding these privatization contracts, with little indication of subsiding anytime soon. In the absence of a specialized international regime to regulate these fast-growing activities, both investors and host states filed twenty-one investment claims to investment tribunals in less than two decades. These filings have invited tribunals to interpret foreign investments in the water industry. The tribunal interpretations have generated the embryonic international regulatory and jurisprudential regime on water services analysed in this Article. Governments must design water related policies that comply with investment treaties because failure to do so results in higher water costs and deters foreign investors from providing much needed high quality services to local populations and industries. Although the investment jurisprudence may be seen as progress towards the regulation of an important service, it also emphasizes the lack of a true global holistic approach to regulate water services.