Policies are Needed to Ensure Wise Use

From a policy perspective, the use of wastewater in agriculture provides both opportunities and challenges that require public intervention. In one sense, wastewater is an effluent requiring treatment or disposal, subject to regulations that protect public health. In the absence of regulations, private generators of wastewater would have little incentive to reduce volume or to manage the flow of wastewater beyond their property line. Because wastewater generation is a negative externality in most settings, regulations and incentives are needed to minimize the potential harm from wastewater in the environment.

Wastewater management has public-good characteristics in that once it is provided, many members of society benefit. At the same time, it is difficult to exclude individuals from enjoying the benefits of a cleaner, healthier environment once the decision has been made to collect and treat all wastewater in a community. The non-rival nature of the benefits and the difficulty of exclusion provide the basis for managing wastewater treatment within the public sector.

The public-goods perspective is appropriate when viewing wastewater as an effluent requiring treatment or disposal. However, when viewing wastewater as a resource, there are notable private benefits for which individuals will be willing to invest time, effort, and funding to enhance their opportunities. The private-goods perspective pertains to both treated and untreated wastewater. Several water agencies in Australia, Israel, and the United States sell treated wastewater (directly or through an aquifer recharge program) to farmers and golf course owners who obtain private benefits through irrigation.^134,351 Often there is a price differential between treated wastewater and fresh water, thus providing a financial incentive for irrigators to select the treated wastewater.^136,371

Farmers in developing countries also obtain private benefits, but the distribution of wastewater among them is much less formal, and the wastewater generally has not been treated. An estimated 80% of the sewage generated in developing countries is discharged untreated into the environment, and half the population is exposed to polluted water sources.^138,391 Many farmers acquire untreated wastewater when they divert irrigation water from a stream or ditch that carries effluent from a nearby city or from households in an urban, periurban, or rural area. Water diversions and the use of wastewater in such settings generate private benefits for the farmers. The public gains also as the farmers remove the low-quality water from streams and ditches. However, the primary motivation for farmers is to boost their productivity and increase their net returns in agriculture. By doing so, they risk the health of their families through exposure to untreated wastewater, and they create situations in which consumers also are at risk of eating harmful produce. Public policies are needed to reduce these risks and to optimize the management of wastewater from the public’s perspective.

Policy Issues in Developed Countries

Current policy issues regarding wastewater use for irrigation are best described separately for developed and developing countries. In developed countries, the primary policy issues involve economics and finance. The public generally has already determined that protective water quality guidelines must be followed when using wastewater for irrigation. The technology for treating wastewater is well understood, and advances in technology that lower the costs and increase the benefits will be forthcoming in response to market demands and in accordance with government-sponsored research programs. The question will not be whether wastewater will be treated but who will pay for treatment and how much of the cost will be passed along to the users. In some areas, public officials also will seek to determine the economically optimal level of wastewater treatment, as a function of its intended uses.¹⁴⁰¹

Key policy questions will also involve the appropriate levels of government involvement in wastewater treatment and reuse programs. Where the private, farm-level benefits of wastewater use are notable, farmers should be financially motivated to invest in production methods and develop market outlets that support irrigation with wastewater. Farmers should also be able and willing to pay for treated wastewater delivered by a public agency or water user association. Using contingent valuation methods in a survey of Greek farmers, Bakopoulou et al.¹⁴¹¹ determined that 58% of the participants would be willing to pay half the fresh water price to purchase treated wastewater for irrigation. Small-scale farmers on the island of Crete expressed a greater willingness to pay for treated wastewater after attending a session in which they learned of the private and social benefits of wastewater irrigation.¹⁴²¹

Farmers should also have incentive to invest in communal facilities for collecting, treating, and delivering wastewater to farms, as the price and availability of wastewater improve over time, relative to the price and availability of fresh water. Public agencies can hasten a farm-level switch from fresh water to wastewater with water pricing and investment incentives and also by informing farmers and consumers of the safety and benefits of irrigating with treated wastewater.