Septic Systems: What Owners Outside City Sewer Should Know
Plenty of properties around Rockwall County sit outside city sewer. A septic system is low-maintenance until it is not, and the failures are expensive.
September 5, 2026 · 5 min read
If your property is outside a city sewer service area, everything that leaves the house goes into a tank and then into a drain field on your own land.
It works quietly for years, which is exactly why it gets neglected.
How it works, briefly
Waste enters a tank. Solids settle, grease floats, and the relatively clear liquid in the middle flows out to the drain field, where it disperses into the soil and is treated biologically.
Two things follow from that. The tank has to be pumped periodically to remove accumulated solids, and the drain field has to be able to absorb liquid.
Pumping
How often depends on tank size, household size and usage. It is not optional and it is far cheaper than the alternative.
If solids are never removed, they eventually carry over into the drain field. A drain field clogged with solids is the expensive failure — replacement rather than maintenance.
Protecting the drain field
- **Do not drive or park on it.** Compaction destroys its ability to absorb.
- **Do not build on it** — sheds, patios, pools.
- **Keep trees away.** Roots seek water and a drain field is a water source. Our guide on tree roots in sewer lines covers the same mechanism.
- **Divert surface water away from it.** A saturated field cannot absorb more.
- **Do not route downspouts or irrigation onto it.**
What not to put down the drain
A septic system depends on biological activity. Things that kill or overwhelm it cause problems:
- Grease and cooking oil in volume.
- Anything not designed to break down — wipes of any kind, including those labelled flushable, hygiene products, paper towels.
- Harsh chemicals in quantity — drain cleaners, solvents, excessive bleach.
- Paint and paint cleanup.
- Water softener discharge, depending on the system — worth asking about.
- Very large volumes of water at once, which pushes liquid through before solids can settle.
Warning signs
- Slow drains throughout the house rather than at one fixture.
- Gurgling from drains.
- Sewage odour indoors or outdoors.
- Unusually green, lush grass over the drain field.
- Soggy ground or standing water over the field.
- Backup at the lowest fixture in the house, which is usually where it shows first.
Any of those means have it looked at rather than waiting.
Selling or buying
A septic inspection is worth having on any property transaction. A failing system is a substantial cost and it is far better identified before closing than after.
Inside the house
Everything from the house to the tank is ordinary plumbing, and that is our work. If drains are slow, backing up or smelling and you are on septic, call (469) 338-5533 — we will help you work out whether the problem is inside the house or out at the system.
Frequently asked
How often should a septic tank be pumped?
It depends on tank size, household size and usage. What matters is that it happens — if solids are never removed they carry over into the drain field, and a clogged drain field is a replacement rather than a maintenance item.
What should never go into a septic system?
Wipes of any kind including flushable ones, hygiene products, paper towels, grease and cooking oil in volume, harsh chemicals in quantity, and paint. Nothing but waste and toilet paper.
What are the signs of a failing septic system?
Slow drains throughout the house, gurgling, sewage odour, unusually lush grass over the drain field, soggy ground above it, or backup at the lowest fixture in the house.
Can I park on my drain field?
No. Compaction destroys the soil's ability to absorb liquid, and that is the whole function of the field. Keep vehicles, structures and trees off it and divert surface water away from it.