Two houses on the same street. Similar age, similar footprint, similar price point. One owner is legally required to pump the septic tank every three years. The other gets seven. Neither number has anything to do with tank size, household size, or how well either family keeps up with maintenance.
It comes down to which side of a geological boundary the lot sits on. That boundary runs through West Lake Hills, and it is written into a city ordinance that most sellers, most buyers, and more than a few agents have never opened. It is the edge of the Edwards Aquifer Recharge Zone, and once you know it exists, it changes what you check before you write an offer or sign a listing agreement.
The Ordinance That Splits The City In Two
West Lake Hills sits over ground where, according to the city's own stormwater education materials, portions of the community fall within both the Edwards Aquifer Contributing Zone and the Recharge Zone. In the Contributing Zone, rainfall soaks into the ground and flows downhill as spring-fed streams. Where those streams reach the Recharge Zone, limestone crevices and caves let that water drop directly into the aquifer below, the same aquifer much of the region depends on for drinking water.
That geology is the reason the city treats septic maintenance differently depending on where a lot falls. Under Ordinance No. 2020-018, residential septic systems located in the Edwards Aquifer Recharge Zone must be pumped once every three years. Systems outside that zone, even elsewhere in the same city, get a seven-year interval. A generic septic guide will tell you tanks typically need pumping every three to five years. In West Lake Hills, the actual legal requirement is not a range. It is a fixed number set by an ordinance, and it depends on a line you cannot see standing in the front yard.
Same Street, Different Utility Bill
The recharge zone line explains why maintenance schedules differ. A second, separate fact explains why some West Lake Hills homes are not on septic at all. The city maintains wastewater service through a third party, SI Environmental, and offers a process for connecting properties to a wastewater main or extending service into a new area. Where the terrain makes gravity sewer lines impractical, homes connect through a grinder pump instead, which carries its own monthly fee of $35, a charge the city added starting November 1, 2024.
That means a buyer touring West Lake Hills is not comparing apples to apples from one listing to the next. One home may be entirely off municipal wastewater and subject to the ordinance's pump-out clock. The next may be tied into SI Environmental with a grinder pump quietly adding a recurring line item to the monthly cost of ownership. Neither fact tends to show up in a listing description. Both show up in the closing paperwork, and both should show up in your due diligence before you get there.
There is a timing wrinkle worth flagging here too. The wastewater rate schedule the city published covers the period from August 29, 2024 through August 28, 2026, a window that closes in the next few weeks. Anyone under contract right now on a wastewater-connected property should confirm whether a new rate schedule has been adopted before assuming the current numbers hold at closing.
Here is how the three scenarios actually compare:
| Situation | What governs it | Maintenance cadence | What shows up at closing |
|---|---|---|---|
| Septic, inside the Recharge Zone | Ordinance 2020-018 | Pump every 3 years | TXR-1407 disclosure, pump-out records |
| Septic, outside the Recharge Zone | Ordinance 2020-018 | Pump every 7 years | TXR-1407 disclosure, pump-out records |
| Connected to wastewater main | SI Environmental billing | No pump-out required | Monthly fee, possible $35 grinder pump charge |
What Actually Lands On The Disclosure Form
Texas Property Code Section 5.008 requires most sellers of a single-family home to deliver a written disclosure notice, and when a septic system is present, that notice is paired with a separate form, TXR-1407, that spells out the type of system, its age, and its maintenance history. This is not paperwork sellers can leave blank and hope nobody asks about. Concealing a known defect, whether it is a failing drain field or a tank that has gone past its legally required pump-out date, exposes a seller to claims under the Deceptive Trade Practices Act, which can include actual damages plus attorney fees.
As one guide to Texas septic transactions puts it, "an honest disclosure with known issues is far safer than a clean form that turns out to be wrong." In West Lake Hills specifically, that means a seller's disclosure should be able to answer a question a buyer's agent in this market will eventually ask: is this system on the three-year clock or the seven-year clock, and when was it last serviced against that clock. A handful of transactions fall outside the disclosure requirement entirely, including foreclosures, transfers between spouses, and sales of new construction that has never been occupied, which matters here given how much spec-home activity moves through this corridor.
The Financing Wrinkle That Shows Up Later
Septic condition does not just affect disclosure risk. It affects who can actually close. FHA and VA loans require the septic system to meet minimum property standards, which means any deficiency has to be repaired before closing, not after. Conventional financing sits in a gray area depending on the lender and appraiser. Cash buyers can close regardless of condition, which is part of why septic-related repairs tend to price differently depending on the buyer pool a seller is marketing to.
Layer the recharge zone rule on top of that. A home inside the zone that has not been pumped in more than three years is already out of compliance with the city's own ordinance before an FHA appraiser ever sets foot on the property. That is the kind of detail that turns a routine financed purchase into a last-minute repair negotiation, and it is entirely avoidable with a records check two weeks earlier.
If You're Selling On Septic, Sequence It Like This
- Confirm which zone the lot sits in. The TCEQ Edwards Aquifer map viewer is the state's own tool for checking recharge, transition, and contributing zone boundaries.
- Pull your pump-out records and compare the last service date against the three-year or seven-year clock that applies to your zone.
- If you are due, schedule the pump-out before you list. Expect to pay in the range of $250 to $400.
- Get a professional inspection covering tank condition and drain field flow, typically $300 to $500.
- Complete the TXR-1407 form yourself, with dates and documentation attached, and include it with your listing materials rather than waiting for a buyer to ask.
If You're Buying, Ask These Before The Option Period Ends
- Which zone is this lot in, and does the pump-out history match the required cadence for that zone?
- Is the home on septic or connected to SI Environmental wastewater, and if it's the latter, is there a grinder pump and what is the current monthly fee?
- If financing with FHA or VA, has the septic system already been evaluated against minimum property standards, or is that evaluation still pending?
- Is the wastewater rate schedule still the one set in 2024, or has an updated schedule been adopted now that it is set to expire on August 28, 2026?
The Practical Read
The zip code tells you very little about which septic rules apply to a given West Lake Hills lot. The zone does. Two homes a few doors apart can carry different legal obligations, different recurring costs, and different financing friction, and none of it is visible from the curb or the listing photos. Knowing which side of that line a property sits on, before you write the offer or sign the listing agreement, is the difference between a closing that goes smoothly and one that stalls over a form nobody filled out correctly.
Frequently Asked Questions
How do I find out which aquifer zone my West Lake Hills property is in? The TCEQ's Edwards Aquifer map viewer lets you check recharge, transition, and contributing zone boundaries by address. City staff can also confirm zone status for a specific parcel.
Does any of this apply if my home is already on municipal wastewater? The three-year and seven-year pump-out rules apply only to septic systems. Wastewater-connected homes skip that obligation entirely but should confirm whether a grinder pump fee applies and whether current billing reflects the most recent rate schedule.
Does buying with cash make any of this irrelevant? Cash buyers are not held to FHA or VA minimum property standards, so financing-driven repair timelines do not apply. Disclosure obligations and the underlying maintenance requirements still do, and a septic system out of compliance with the city's ordinance is still worth knowing about before you close.
Every West Lake Hills transaction carries details like this that never make it into a listing sheet. If you are buying, selling, or simply trying to understand what a specific address actually requires before you commit, Courtney Hohl can walk through the zone, the disclosure, and the financing implications together. Book a Private Market Consultation to get the full picture before you're under contract.
