Why Water Utilities Use Tiered Residential Water Rates

Having established that water conservation is an important public policy objective, the next question is how utilities encourage efficient water use while continuing to provide reliable service. Public education, conservation outreach, rebate programs, leak detection, and infrastructure improvements all contribute to reducing unnecessary water consumption. Another widely used conservation tool is the design of residential water rates themselves.

Water rates are more than a method of recovering the cost of providing service. The structure of those rates can influence customer behavior by creating financial incentives that encourage efficient water use while preserving access to essential household consumption. For this reason, many regulated water utilities have adopted inclining block, or tiered, residential rate structures.

Under an inclining block rate structure, residential water consumption is divided into successive usage blocks, commonly referred to as tiers. Water used within the first tier is billed at the utility's standard base consumption rate. As consumption exceeds that initial allocation, additional water is billed at progressively higher rates. These higher-priced tiers are intended to encourage conservation by increasing the cost of higher levels of water use.

Rather than reducing the price of essential water use, inclining block rates increase the price of additional consumption beyond the initial allocation. In this way, the rate structure uses progressively higher prices to encourage customers to reduce discretionary water use while preserving the standard Tier 1 price for ordinary household consumption.

New York has incorporated these principles into the regulation of investor-owned water utilities. Recent Public Service Commission proceedings involving both Liberty Utilities and Veolia Water New York demonstrate that residential conservation rate structures continue to play an important role in utility rate design. In approving the Veolia Water New York Joint Proposal, the Commission explained that "the rate structure established in the Joint Proposal is conservation-oriented, with inclining rates designed to discourage discretionary usage, particularly in the summer."¹¹ This language confirms that the purpose of the approved inclining block rate structure is not simply revenue collection, but the encouragement of efficient water use through conservation-oriented pricing.

The Liberty Utilities Threshold Analysis illustrates how seriously the Commission treats the operation of these conservation rates. Rather than simply approving the existing rate structure without further review, the Commission-approved Joint Proposal required Liberty to examine whether residential customers whose consumption consisted primarily of indoor water use were reaching Tier 4 during non-peak months. If such customers were identified, Liberty and Department of Public Service Staff were directed to evaluate whether additional study or modifications should be considered. This requirement demonstrates that conservation-oriented rate design is expected to achieve its objectives while remaining subject to ongoing review and evaluation.¹²

The economic rationale underlying tiered rates is well established. Water demand is not perfectly fixed. While certain household uses are essential, other uses are more responsive to price. By increasing the cost of higher levels of consumption, utilities create an economic incentive for customers to reduce discretionary water use. This approach seeks to balance efficient resource management with reliable water service by encouraging conservation where customers have the greatest practical ability to reduce consumption voluntarily.

Industry guidance reflects these same principles. Water resource planning publications describe inclining block rates as a means of providing conservation price signals while preserving the standard rate for an initial level of residential consumption. Water pricing is therefore intended not merely to recover utility costs, but also to encourage the efficient use of a limited public resource. These concepts have become common elements of modern water utility rate design and are reflected in conservation planning throughout the United States.¹³

Importantly, the existence of conservation-oriented rate structures does not, by itself, answer every question regarding how those structures should operate. Conservation pricing establishes an important public policy objective, but it also raises practical questions concerning how different patterns of residential water use interact with the rate design. As utilities have gained experience with tiered rates, regulators have increasingly examined whether the intended conservation incentives operate consistently across different customer circumstances.

Understanding that question requires examining one distinction that has become increasingly important in both research and utility practice: the difference between essential and discretionary residential water use. That distinction forms the focus of the next chapter.