Preventing sewer backups in Houston storms

Houston gets a lot of rain. The National Weather Service 1991 to 2020 normals for Bush Intercontinental Airport list 51.84 inches of precipitation a year, with June, October and May the wettest months. Sanitary sewers are built to carry wastewater, not stormwater, but the EPA's page on sanitary sewer overflows says sewer defects can allow stormwater and groundwater to overload the system. When that happens, sewage can overflow from manholes or back up into homes. The EPA lists blockages, line breaks, power failures and improper sewer design as other causes, and estimates at least 23,000 to 75,000 overflows a year nationally, not counting backups into buildings.

Houston Public Works' Wastewater Operations runs more than 6,100 miles of pipelines, over 380 lift stations and 40 treatment plants. It says 70 percent of sewer overflows in Houston are caused by clogs from fats, oils, grease and flushed wipes. That makes everyday habits part of storm preparation: a grease-narrowed line has less room for a surge.

Ownership lines matter for cost. Sugar Land's water utility emergency page is typical of the region: the city maintains the mains, and the property owner is responsible for the wastewater line that connects to them, including breaks under the yard. In Houston, the city's service line page directs service line questions to 311 at (713) 837-0311 and says the property owner owns the water line from the meter to the house. In unincorporated areas, call the MUD operator on your water bill.

• Keep grease and wipes out of drains. Given the 70 percent figure above, this is the cheapest step.
• Find your cleanout. It is usually a capped pipe near the foundation or in the yard. A plumber uses it to clear the main line, and a cap that is missing or broken can let stormwater in.
• Have the main line checked. If you have had more than one main line stoppage, a camera inspection can show roots, offsets or a sagging section. HomeGuide's 2026 drain cleaning guide puts main line clearing at $200 to $500 and a camera inspection at $125 to $500 nationally.
• Ask about a backwater valve. A backwater valve is a one-way check valve on the building drain that closes when sewage tries to flow back toward the house. It needs a permit where the city requires one, correct placement and periodic cleaning, so get a licensed plumber's recommendation for your specific line.
• Know where your water shutoff is. If a drain is backing up, stop running water in the house so you are not adding to it.

Often not by default. The Texas Department of Insurance's homeowners insurance guide lists backup of sewers or drains as an optional endorsement, not standard coverage. It says most home policies do not cover flood damage, and that most flood policies have a 30-day waiting period before they take effect. Read your policy now and ask your agent whether a sewer backup endorsement is included and what its limit is, since a policy bought just before a storm may not help.

1. Stop using water: no flushing, laundry or dishwasher.
2. Keep people and pets away from the water; sewage carries bacteria.
3. Photograph the damage for your insurer before cleanup.
4. If the problem is your line, call a licensed plumber; if it is the public sewer, call your utility.

Our emergency guide covers the first minutes, and our drain cleaning and sewer line guides cover the repairs. Flood risk varies by watershed; the Harris County Flood Control District manages 23 primary watersheds across the county's 1,777 square miles.

We are an independent guide, not a contractor, and we do not perform plumbing work or answer phones. To reach a plumber, call one of the licensed contractors listed on this page or see all listed contractors. Questions about this guide: email us. We do not take service requests. Check the license of anyone you hire, including the contractors listed on this page.