As utility services expand throughout the developing world, providers must grapple with how to set prices to recover average costs. Data from a multi-year randomized pricing experiment among nearly 1500 recently-connected piped water customers in Vietnam reveal month-to-month demand persistence. Based on structural demand estimation, we document how endogenous preferences, if unaccounted for, can lead to low take-up and thereby threaten the financial viability of the new water utility. We also show that such demand persistence calls for pricing schemes that defer lump-sum payment, effectively allowing future consumers to subsidize their present selves.