Should Amberton Adopt Direct Potable Reuse? A Debate Kit

Resolution: "The city of Amberton should adopt direct potable reuse, treating its own wastewater back to drinking-water quality and returning it directly to the supply."

Background: Amberton is a fictional inland city with no coastline, and its one river runs low in dry years, so its leaders are weighing water reuse. Two forms exist. In direct potable reuse, advanced treatment cleans wastewater to drinking quality, and that clean water then goes straight into the supply. In indirect potable reuse, the same treated water is first stored in an aquifer or reservoir, which acts as an environmental buffer, before it re-enters the supply. Either path relies on several barriers, a key one being a reverse osmosis membrane, a filter fine enough to block most contaminants. Reuse is neither new nor untested, since Orange County's Groundwater Replenishment System in California is the world's largest indirect reuse plant, producing about 130 million gallons of water per day. The question for Amberton is which route to take, and whether residents will accept it.

Assign two teams. An affirmative team argues for the resolution, and a negative team argues against it. A moderator keeps time. The rest of the class judges with the rubric.

Case for direct potable reuse:

1. Reuse turns wastewater, which the city already produces, into a steady local supply. That supply does not depend on rainfall. For a dry inland city, it offers water security the low river cannot. (General reasoning about local supply.)

2. Cleaning wastewater to drinking quality already works at city scale. Orange County's Groundwater Replenishment System is the world's largest such plant, at about 130 million gallons per day. That scale is evidence that the treatment technology has been proven. (Source: Orange County Water District.)

3. Amberton has no coast, so seawater desalination is out. Importing water would mean a long, costly pipeline. A fictional Amberton public-works briefing, prepared for this debate, argues reuse is the only major new supply the city can build within its own borders. (Illustrative briefing created for this debate, not a documented figure.)

4. Direct reuse needs less land than indirect reuse. It does not require an aquifer recharge site or a reservoir buffer. A fictional city engineer argues Amberton lacks the space and geology for one. (Illustrative testimony created for this debate.)

Case against direct potable reuse:

1. Public acceptance is a real obstacle. A fictional Amberton resident survey, run for this debate, finds many residents uneasy about drinking treated wastewater. A system the public distrusts can fail even when it is safe. (Illustrative survey created for this debate.)

2. Advanced treatment is costly to build and run. The reverse osmosis step uses roughly 3 to 4 kilowatt-hours of energy for every 1,000 gallons treated. Conventional treatment of fresh water uses only about 1 to 2. So reuse carries a high ongoing energy cost. (Source: industry engineering references on reverse osmosis energy use.)

3. A safer-by-design option exists. Indirect potable reuse adds an environmental buffer, an aquifer or reservoir, before the water returns to the supply. A fictional Amberton ratepayer coalition argues the city should choose that route, or expand conservation first. (Illustrative testimony created for this debate.)

4. Reducing demand is often cheaper than building a new supply. Opponents argue Amberton should push conservation as far as it can first. Cutting demand avoids the capital cost of any new plant, and reuse should be built only if conservation proves too little. (General reasoning about conservation as a first option.)