Los Alamos DPU Warns Residents to Install Backwater Valves

The Los Alamos Department of Public Utilities (DPU) on December 30, 2025 reminded customers to check whether their homes or businesses are protected from potential sewer backups with properly installed and maintained backwater valves. DPU said it maintains a rigorous program for cleaning and repairing sanitary sewer mains but cautioned that obstructions can still occur, producing costly cleanup and public health risks.

Under the national plumbing code, a backwater valve is required when any plumbing fixture, such as a toilet, shower, or floor drain, is located below the elevation of the next upstream sewer manhole. A DPU study conducted in 2011 identified more than 2,400 local properties that appear to meet that condition and therefore may need backwater valve protection. Property owners can check whether their address is flagged by visiting ladpu.com/backwater and using the map links provided there.

The reminder emphasized that prevention of sewer backups is a shared responsibility: DPU manages main-line maintenance but when the plumbing code requires a backwater valve, installation, ownership, and ongoing maintenance fall to the property owner. Because backwater valves are the owner’s responsibility, DPU does not keep records indicating where they have been installed. DPU warned that failure to comply with code requirements may increase an owner’s liability if a backup occurs.

In most cases, a standard backwater device will protect a home from a sewer main backup, DPU said, but properties with especially low service connections may require additional measures. Examples include a basement sewer connection or homes with later additions that sit lower than the original plumbing; those properties can need a grinder pump with a more robust check valve or other solutions tailored by a qualified plumber or engineer.

For residents concerned about risk, DPU is available to help determine whether a property is at risk and whether a backwater valve is advisable or required. Customers seeking assistance or wishing to schedule an appointment with a DPU technician may contact the Customer Care Center at 505.662.8333 or customercare@losalamosnm.gov.

The advisory underscores the practical and legal responsibilities of property owners in limiting sewer-related damage. For Los Alamos residents, verifying elevation relationships with the sewer system and, if necessary, arranging for proper equipment can reduce property damage, protect public health, and mitigate potential liability.