Approximately 40 million people in the US are served by private, and frequently untreated, wells. Our best estimate is that 1.3 million cases of gastrointestinal illnesses (GI) per year are attributed to consuming water from untreated private wells in the US, but in reality, there are no robust epidemiological data that can be used to estimate cases of GI attributable to these sources. We propose the first randomized controlled trial (RCT) to estimate the burden of GI associated with private well water. We will test if household treatment of private well water by ultraviolet light (UV) vs. sham (inactive UV device) decreases the incidence of GI in children under 5. We will also examine the presence of viral, bacterial, and protozoan pathogens in stool and well water from participants. These data will fill a knowledge gap on sporadic GI associated with federally-unregulated private water supplies in the US.

Investigators will conduct a triple-blinded randomized controlled trial of a whole-home UV water treatment device in southeastern Pennsylvania. Participating families will be randomized to receive an active UV device or a sham (inactive) UV device. Following the installation of the device, participants will be followed for one year. During that year, participants will respond to weekly text messages to report the presence of symptoms associated with gastrointestinal and respiratory illness in their children. Upon reporting symptoms, participants will complete an illness questionnaire on details regarding the illness and other potential exposure events. A subset of participants will submit groundwater samples as well as stool and saliva samples from their children. Water and stool samples will be analyzed for common waterborne pathogens. Saliva samples will be analyzed for immunoconversions to common waterborne pathogens (exploratory aim).

Under the guidance of an interdisciplinary advisory committee we will execute the following aims:

Aim 1- Quantify the incidence rate of endemic childhood GI associated with consuming untreated private well water and compare that to the incidence rate of consuming well water treated by UV.

Aim 1a- Construct a Quantitative Microbial Risk Assessment (QMRA) using water quality data we collect to estimate the risk of childhood GI associated with consuming untreated private well water and compare the incidence from the risk model to the incidence we calculate in Aim 1.

Aim 2- Identify, quantify and compare viral, bacterial and protozoan pathogens in stool of children consuming UV treated or untreated (sham) private well water (including both asymptomatic and symptomatic cases).

Aim 3- Explore the presence of pathogens in untreated well water and stool samples of children consuming untreated private well water (sham group only).

Inclusion Criteria:

• Child resides in Adams, Berks, Bucks, Carbon, Chester, Columbia, Cumberland, Dauphin, Delaware, Lackawanna, Lancaster, Lebanon, Lehigh, Luzerne, Monroe, Montgomery, Montour, Northumberland, Northampton, Perry, Pike, Schuylkill, Wayne, Wyoming, and York county in Pennsylvania and all counties in New Jersey.
• Household is served by a private well
• Participant child is under the age of 5 (under 4 at time of enrollment), who is a full-time resident of the home and drinks untreated well water
• Parent/guardian has access to a phone with texting capabilities

Exclusion Criteria:

• Child participant is immunocompromised
• Child participant has a chronic gastrointestinal condition
• Child takes daily oral steroids
• Household treats water for microbiological contamination before consumption
• Child exclusively drinks bottled water

Participants, device installers, investigators, and outcomes assessor will all be blinded.