Fall Sewer Checklist for Houston: Before the Fronts and the Rain
Most fall sewer checklists are written for places where the ground freezes. Houston's ground does not freeze, but it does something else in the fall that is just as hard on a pipe: it gets wet again after three months of shrinking. Add the tail end of hurricane season, the pecan and tallow leaf drop, and Thanksgiving, and late September is the right week to spend an hour on the sewer line. Here is the list.
What the season does to a Houston lateral
By the end of September the gumbo clay has been drying since July. It has shrunk away from the slab, away from the lateral, and opened cracks you can put a hand in. The first cold front — usually October, sometimes late September — brings a couple of inches of rain on that dry clay and it swells back, fast and unevenly. Pipes that settled a fraction over the summer get pushed the other way. Joints that were open a half inch close on one side and open on the other. Under the slab, cast iron hubs that held all summer let go when the slab lifts an eighth of an inch on the wet side.
Meanwhile the season is not over. The National Hurricane Center's season runs to November 30, and Houston has taken tropical rain in October more than once. A main under surcharge in a big rain backs up into the lowest fixture of every house on the block whose lateral has no backwater valve.
The checklist
1. Run the drain test. Fill the lowest tub or shower, then drain it while the washing machine empties. Watch and listen. Slow draining, or a gurgle from a toilet or floor drain, means the main line is already partly blocked. Do this before the guests arrive, not after.
2. Find and open the cleanout. The capped 4-inch pipe at the front or side of the house. Clear the shrubs and the mulch off it, make sure the cap turns, and put it back. If the house was built before 1980 and you cannot find one, there probably is not one. Adding a two-way cleanout is $600–$1,500 and it is the best money in this list, because every future inspection and every emergency starts there.
3. Walk the lateral's path. From the cleanout to the street. Look for a strip that is greener than the rest of the yard, a low spot, a sinkhole the size of a dinner plate, or ground that is wet on a dry day. Any of those is a leak.
4. Check the yard drains and the area drains. Patio drains, French drains and the grate at the bottom of the driveway are often tied into the storm system, but on some older Houston houses they are tied into the sanitary sewer — which is illegal now and common then. If your yard drain sends storm water into your lateral, every big rain overloads it. The camera can tell.
5. Look at the trees. Water oaks, sycamores and Chinese tallow drop their leaves in November and December here, later than most of the country. Leaves themselves do not clog a sewer, but the roots underneath have spent August finding your joints. If a line was snaked for roots this summer, this is the month to camera it, before the holiday.
6. Deal with the grease before Thanksgiving. The kitchen branch line in a 1970s house is 2-inch cast iron or ABS, and it is coated. A hydro jet ($350–$900) on the kitchen line and the main in October is cheaper than the same job at holiday rates in November.
7. Think about a backwater valve. A sewer backup Houston houses get during a storm, that clears on its own when the rain stops, means the main surcharged, not your lateral. A backwater valve on the lateral — a flap that closes when flow reverses — stops the street coming into the house. It is $1,500–$3,500 installed in a Houston yard, it needs a permit, and it needs a cleanout on the house side. Not every house needs one; a house that has flooded from the sewer once will again.
8. Water the foundation. The soaker hoses along the grade beam that kept the clay from shrinking in August are worth running until the fronts start. Even swelling is easier on the slab and on the cast iron under it than a dry summer followed by a wet week.
9. Know the numbers before you need them. Your MUD operator or 311 for the main. Your insurance agent for whether the policy has a sewer backup endorsement — most Texas policies do not include it by default. A sewer contractor with a Responsible Master Plumber license and a camera, for your side of the property line.
What the first front will tell you
The week after the first real rain is diagnostic. A lateral that is leaking will show a wet, sunken stripe over its path once the clay has taken up water. A house whose cast iron let go when the slab moved will get a sewer smell in the back bathroom that a cup of water in the drain does not fix. And a main that surcharged will have backed up several houses on the street at once. Each of those is a different phone call, and signs of a broken sewer line sorts them.
The order of operations if something is wrong
- Stop running water.
- Cable or jet to get the house draining — a same-day job.
- Camera inspection to see why it stopped, with the break located and marked.
- A written price for the fix that matches the footage: spot repair, replacement or lining.
- Permit, work, inspection, second camera pass.
An hour in late September, before the fronts, before the leaves, before the guests, is what keeps step two from being a Saturday-night emergency call. The pricing page has what each of those steps costs in 2026.
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