What should I know about septic systems and water wells in the Texas Hill Country?

A Hill Country property on a septic system and a private well carries due diligence a city-connected house does not. The buyer is responsible for inspecting the on-site sewage facility, testing and evaluating the well, and gathering permits and maintenance records, all inside the option period. TREC form 61-0 covers groundwater and surface water rights.

The difference a city tap makes

Inside Boerne's city limits, water and wastewater are a utility account. Boerne's drinking water comes from three sources — surface water from Canyon Lake purchased through the Guadalupe-Blanco River Authority, Boerne City Lake, and local wells in the Trinity Group aquifers (City of Boerne). Somebody else owns that infrastructure, tests that water and fixes it when it breaks.

On an acreage property outside the system, you own both ends. The water comes out of a well you own, and the wastewater goes into a treatment system you own and are responsible for maintaining. Two pieces of private infrastructure, each with its own failure modes, neither one covered by a standard home inspection.

That is not an argument against buying acreage. It is an argument for treating septic and well as their own diligence items with their own specialists, on their own timeline, starting the day the contract goes effective.

The septic side: on-site sewage facilities

Texas calls a septic system an on-site sewage facility, or OSSF. Two broad families show up around Boerne:

Conventional systems — a tank and a drainfield, relying on soil to treat effluent. Thin soil over limestone, which is much of the Hill Country, limits where these work.
Aerobic treatment units — an engineered system with an air pump, a treatment tank, chlorination, and usually spray heads distributing treated effluent over the yard. These are common where soil will not support a conventional drainfield, they use electricity, they have mechanical parts, and they generally carry an ongoing maintenance obligation.

That last point is the one buyers miss. An aerobic system is not install-and-forget. It typically requires a maintenance provider under contract and periodic service. A seller who let the contract lapse leaves the buyer inheriting a system that has not been serviced and may not be operating to its permit.

What to inspect and ask about:

Tank condition, and whether it has been pumped — when, and by whom
For an aerobic unit: the air pump, chlorinator, control panel, alarm, spray heads and their coverage
The drainfield or spray area — surfacing effluent, soggy ground, odor, unusually green strips
Whether the system as built matches the system that was permitted
Whether the system is sized for the house as it exists now, particularly if bedrooms or a guest quarters were added after the original permit
Where the components are, physically, and whether anything has been built or parked over them

Who inspects it: a septic or OSSF inspector, not a general home inspector. A general inspection under the TREC Property Inspection Report, form REI 7-6, effective 02/01/2022 is not a septic inspection (TREC forms). Hire the specialist separately.

Documents to request from the seller: the OSSF permit, the as-built or site plan showing component locations, the maintenance contract and service records for an aerobic unit, and pumping records. On-site sewage facilities in Texas are permitted through a local authorized agent — ask Kendall County which office holds permit records for the address, and request the file rather than relying on the seller's memory.

The well side

A private well is a mechanical system plus a water quality question plus a supply question. Three separate things.

Mechanical. Pump, pressure tank, wiring, pitless adapter, well cap and casing, plumbing back to the house. A well that produces water today can still have a pump near the end of its life.

Quality. A general home inspection does not test water. Testing is its own item, done by a lab or a qualified provider, and what gets tested is a choice — bacteriological is the baseline, and other analyses are worth discussing based on the area and the age of the well. Ask your lender early whether the loan program requires a water test and what result it requires, because that answer sets a deadline.

Supply. How the well performs over time is not visible from a single tap opening. Ask what the well has done historically, and ask the owner directly about any period when it did not keep up.

Documents to request: the well report or driller's log, any registration with the groundwater district, pump installation and service records, water test results, and — critically — any shared well agreement. A well serving more than one property is a legal arrangement, not a plumbing arrangement, and what it says about cost sharing, maintenance, access and what happens when the pump fails is a document for a Texas real estate attorney to read before closing, not after.

Groundwater is regulated, and the rules change

Groundwater in Kendall County is regulated by the Cow Creek Groundwater Conservation District. The district monitors conditions using data from roughly 42 monitor wells, stream gauges on Cibolo Creek and the Guadalupe River, and more than 100 rain gauge sites, and it sets drought stages that carry pumping restrictions (Cow Creek GCD).

Drought stage is not a fixed fact and this page will not state one. It moves. Check the current stage and the current rules at ccgcd.org before you rely on any number, including anything you read in an article. What matters to a buyer is the structure: there is a district, it has authority over groundwater use, and its rules can restrict what a well owner may pump.

Cow Creek also appears as a taxing entity on Kendall County tax bills, alongside the county, the school districts, the cities and the special districts (Kendall AD).

Boerne is in Kendall County, not Bexar County. The Edwards Aquifer Authority rules people read about in San Antonio are a different regulator over a different aquifer, and the appraisal district is Kendall Appraisal District, not Bexar CAD.

The disclosure forms that touch this

Two forms matter here (TREC contract forms):

Seller's Disclosure about Groundwater and Surface Water Rights, form 61-0, effective 07/01/2026. Water rights on a rural Texas property are not automatically what a buyer assumes, and the form exists to put the seller's statements about them in writing.
Seller's Disclosure Notice, form 55-1, effective 05/28/2026, the general disclosure, which is where a seller reports known condition issues including water and sewer.

Neither is a substitute for an inspection. A disclosure records what the seller says they know. An inspection records what a specialist finds.

Sequence it against the option period

The option period is an unrestricted right to terminate, and it expires at 5:00 p.m. on its final day whether or not the septic inspector had an opening. On a well-and-septic property the buyer is scheduling two specialists and a water lab, and requesting records from a county office and possibly a groundwater district, on a clock that does not extend itself.

Order of operations that works:

Contract effective. Option fee delivered to the title company on time.
Same day: book the general inspection, the septic inspection and the water test. Do not wait for the general inspector's report to decide whether to book the others.
Same day: request the OSSF permit file from the county and the well records from the seller.
Ask the lender what the loan program requires for water and septic.
Read the shared well agreement, if there is one, with an attorney.
Decide before the option period ends.

Where the line is

A real estate agent can sequence the work, pull the records and tell you what is normal for the area. Interpreting a shared well agreement or a water rights reservation is work for a Texas real estate attorney. The condition of the system is a licensed inspector's call. Current groundwater rules come from the Cow Creek Groundwater Conservation District. Permit history comes from Kendall County. Loan requirements come from your lender.

Questions about a specific property?

Call or text 830-446-3847 · Email heath.shepard@kw.com

This page explains the due diligence a septic-and-well property requires. It is not legal advice, and it is not an inspection. Condition questions go to a licensed inspector, shared well agreements and water rights go to a Texas real estate attorney, and current groundwater rules come from the Cow Creek Groundwater Conservation District.