Protect your home from sewer overflow

Published on December 30, 2025

Los Alamos Department of Public Utilities (DPU) is reminding customers to check whether their home or business is protected from potential sewer backups with a properly installed and maintained backwater valve.

Although DPU follows a rigorous maintenance program for cleaning and repairing sanitary sewer mains, obstructions can still occur for a variety of reasons. Sewer backups can be costly to clean up and may create public health risks for occupants.

When a backwater valve is required

The national plumbing code requires a backwater valve 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 in 2011 identified more than 2,400 local properties that appear to meet this condition and may need backwater valve protection. To see if your home requires a backwater valve, visit ladpu.com/backwater on the web and navigate to the map links.

Property owner responsibilities

Prevention of sewer backups is a shared responsibility between DPU and customers. When required by plumbing code, backwater valves must be installed, owned, and maintained by the property owner, and failure to comply may increase the owner’s liability if a backup occurs. Because backwater valves are the property owner’s responsibility, DPU does not have records indicating where they have been installed.

In most cases, a standard backwater device will protect a home from a backup in the sewer main, but homes with especially low service connections may require additional protection such as a grinder pump with a more robust check valve. Two examples would be a basement sewer connection or a home with later additions that are lower than the original home sewer plumbing. 

How DPU can help

DPU is available to work with customers to determine whether their property is at risk and whether a backwater valve is advisable or required. In some cases, customers may need risk assessments from qualified plumbers or engineers. Customers with questions or who wish to schedule an appointment with a DPU technician may contact the Customer Care Center at 505-662-8333 or customercare@losalamosnm.gov.

The Los Alamos County Department of Public Utilities is a community-owned utility that provides electricity, natural gas, water, and wastewater services to Los Alamos County. We’re dedicated to delivering safe, reliable service that’s both cost-effective and environmentally sustainable. While we work hard to minimize service outages, they’re sometimes necessary to maintain and improve our systems. If you or someone in your home depend on electricity for medical equipment, we encourage you to join our Medical Alert list to receive advance notice of planned outages. Sign up at https://ladpu.com/medequip.