*2.3. Measurement*

The questionnaire assessed resident's patterns of drinking water source choice, trust in the water utility, their salience of water topics, perceived risk, evaluations of their tap water quality, and demographic factors. We pre-tested and refined the questionnaire (*n* = 60) before conducting the full survey.

### 2.3.1. Tap, Filtered, or Bottled Water

We assume in this study that people may prefer a particular source of drinking water, but their utilization of that source may vary in degree. Thus, preference for filtered water does not necessarily equate to an exclusive reliance on filtered water. To determine the degree to which residents utilize one or more water sources, we asked them to indicate how often in the past six months they drank bottled water, tap water, filtered water from an appliance, such as water filters in pitchers or refrigerators, or filtered water from a sink attachment in their home. We differentiated appliance filters from sink filters because appliance filters are often standard features built into modern refrigerators or are more affordable to purchase, as is the case with water filter pitchers, thus requiring low effort in comparison with sink filters to obtain. Because the focus of this study was on how water source choice could reflect trust in municipal utility, we focused on drinking behavior in the respondents' homes, ensuring that the respondents would associate tap water with the water their local utility provided. We measured responses on a five-point scale from 1 *= Never or almost never* to 5 *= All of the time or almost all of the time*. The residents responded to each of the four potential water source choices.
