What failure looks like on each of the three
On a conventional trench field in the eastern county the signs are the familiar ones — spongy ground over the trenches, whole-house slow drains, odor outdoors after heavy use — and a wet spring is when they appear.
On a spray system there is usually no soggy patch to find. What you get instead is an alarm on the control panel, a unit running constantly or not at all, effluent that smells rather than being near-odorless, cloudy discharge, or heads that have stopped turning and are watering one patch of ground to death. On drip dispersal a blocked emitter zone shows up as liquid surfacing at the lowest emitter rather than over the whole disposal area.
And on any system over thin limestone, water disappearing faster than it should is not good news. Fractured rock accepts liquid without treating it, which is a groundwater problem rather than a plumbing one, and it is the reason a gravity field cannot be approved on that ground in the first place. Limestone and spray fields.
Repairs, and the contract most failures trace back to
On a conventional field: a silted or tilted distribution box, a crushed or root-invaded lateral, solids carried over from a tank that went too long, hydraulic overload from a leaking fixture. On an aerobic unit the common faults are a failed air pump or compressor, a stuck float or control panel, a clogged filter, and spray heads blocked or aimed where they should not be. All of those are repairs.
Most of them also trace back to the same root cause, and it is not mechanical. Texas requires an aerobic system to have a licensed maintenance provider under contract, reporting to the permitting authority and to the owner at least once every four months under 30 TAC 285.90(3). A lapsed contract is the most common compliance failure in this county, and the unit that failed is usually one nobody has inspected in a year. Budget $200–$450 per year for a maintenance contract, varying with visit frequency and travel. Maintenance contracts and reporting.
Not repairable: a trench field sealed across its soil face, or any field on ground that never had the depth to treat with. Over limestone the replacement is normally not another field — it is an aerobic unit with surface dispersal at $12,000–$25,000, or an engineered design where geology and access force one, $15,000–$30,000 depending on design and site access. What replacement involves.
In Texas a repair needs a permit — and an emergency has a clock
Under 30 TAC Chapter 285 a permit and an approved plan are required to construct, alter, repair, extend and operate an on-site sewage facility. Repair is on that list, which surprises people who assume paperwork applies only to new installs. The Texas Commission on Environmental Quality writes the rules, but it is usually not your permitting authority: local programs act as authorized agents and may be stricter than the state minimum, so the local office is the last word.
The exception is worth knowing before you need it. An emergency repair may begin without a permit, but it has to be reported in writing within 72 hours after work starts. Emergency repairs and the 72-hour rule.
A diagnosis visit establishes which of the three systems you actually have, the tank and its sludge level, the control panel and air pump on an aerobic unit, the distribution box or the emitter zones, and a written finding with a repair price or a replacement estimate — $8,000–$20,000 where a field can be rebuilt at all.
All work is performed by TCEQ-licensed installers and licensed maintenance providers working under the county's on-site sewage facility program.