Local History & Public Health
What the 2006 Las Lomas Flood Taught Us About Septic and Public Health
Longtime residents of the Las Lomas area remember 2006 — the year the water came and didn't leave, bad enough that the National Guard was brought in to help the community. But the flood itself was only half the story. What the water uncovered was a hidden problem that had been sitting underground for years: cesspools and unauthorized septic installs. This is why septic done right is a public health issue, not just a construction one.
When the Water Rose
Flooding in a colonia hits different than flooding in town. In 2006, when heavy water swept through the Las Lomas area east of Laredo, homes on large unincorporated lots — many with no drainage infrastructure — watched water pool across yards, roads, and low spots with nowhere to go. The situation grew serious enough that the National Guard was involved in responding to the community's needs.
For families dealing with damaged property and impassable roads, that was already a crisis. But standing floodwater in a community full of aging cesspools and never-permitted septic systems created a second, quieter emergency — one you couldn't see, but could absolutely get sick from.
What Happens When Floodwater Meets a Cesspool
A cesspool is essentially a hole in the ground that collects raw sewage — no treatment, no engineered drainfield, no design. They were common in older colonias built before enforcement caught up, alongside unauthorized installs: systems put in without permits, without soil evaluation, and without inspection.
On a dry day, these systems are already leaching poorly treated waste into the ground. When floodwater saturates the soil and rises above them, something worse happens: the sewage comes up.
⚠ Why Sewage in Floodwater Is So Dangerous
Floodwater mixed with raw sewage carries bacteria like E. coli, viruses such as hepatitis A, and parasites — invisible in the murky water that children walk through, that pools around homes, and that seeps toward shallow water wells.
- Contact with contaminated water can cause gastrointestinal illness, skin infections, and worse
- Contaminated standing water becomes a breeding ground for mosquitoes on top of the sewage risk
- Private water wells in the area can be compromised when contaminated water infiltrates them
- The contamination doesn't leave when the water does — it soaks into the soil where families live
The Real Lesson: The System Underground Matters
Here's the part that stayed with everyone who worked through that period: the homes with properly designed, permitted septic systems handled the same flood fundamentally better. A code-compliant system has a sealed tank, an engineered drainfield sized to the soil, and required separation distances from wells and property lines — all of it designed by rule specifically so that even in bad conditions, sewage stays contained and treated.
This is what the permit system is actually for. The site evaluations, the soil classifications, the setback distances from water wells, the county inspections — none of it is bureaucracy for its own sake. Every one of those rules exists because of what happens when they're ignored and the water rises. The 2006 flood didn't create the cesspool problem — it revealed it.
Where We Are Now
Since those years, Webb County and the state have pushed hard to bring colonia infrastructure up: water and sewer projects in some communities, and stricter OSSF enforcement everywhere else. But plenty of properties in the Las Lomas area and across the 359 corridor still sit on old cesspools or unpermitted systems installed decades ago — often discovered only when a property sells, a system fails, or the next big rain comes.
If that might be your property, the path forward is straightforward: a site evaluation tells you exactly what's in your ground and what a proper replacement looks like. Replacing a cesspool with a permitted system isn't just a legal upgrade — it's protection for your family's health, your well, and your neighbors' too.
The Bottom Line
Floods will come again — that's South Texas. What 2006 taught the Las Lomas area is that the difference between a flood being a property problem and a public health emergency is largely decided before the rain falls, by what's buried in the ground. A permitted, code-compliant septic system is how you make sure that when the water rises, sewage isn't rising with it.
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📞 Call (956) 441-9557Frequently Asked Questions
Why are cesspools dangerous?
A cesspool is an untreated hole collecting raw sewage with no engineered treatment or drainfield. It leaches poorly treated waste into the soil, and during floods, saturated ground can push that sewage to the surface — exposing families to bacteria, viruses, and parasites.
What happens to a septic system during a flood?
A properly designed, permitted system keeps sewage contained in a sealed tank with an engineered drainfield even in bad conditions. Cesspools and unauthorized systems, by contrast, can release raw sewage into floodwater and contaminate soil and nearby wells.
How do I know if my property has a cesspool or unpermitted system?
Many older colonia properties do, often discovered when a property sells or a system fails. A site evaluation by a licensed evaluator tells you exactly what's in your ground and what a code-compliant replacement would look like.
Can floodwater contaminate my water well?
Yes. Floodwater mixed with sewage can infiltrate private wells, especially shallow ones near failing systems. This is exactly why state code requires separation distances between septic components and water wells.
Have questions about your specific property? Call us at (956) 441-9557 or request an evaluation at southtexasseptics.com. We'll give you a straight answer.