A buyer touring a $5 million home in Los Altos Hills and a buyer touring a $4 million home in Los Altos will sign contracts that look almost identical, right up until the contingency list. In Los Altos, the septic box on the disclosure form usually stays unchecked. In Los Altos Hills, that same box often triggers a chain of inspections: a septic evaluation, a well test if the parcel isn't on Cal Water, a review of the private road maintenance agreement that comes with the driveway, sometimes a geotechnical report if the lot sits on any real slope. None of that shows up in the list price. All of it shows up in escrow.
That gap between what the price tag advertises and what the parcel actually requires is the real story behind a number that looks like a mistake the first time you see it. Over the three months ending in May 2026, the median sale price in Los Altos Hills was $5.3 million against $4.2 million in Los Altos, yet the median price per square foot in Los Altos Hills was $1.66 thousand versus $1.94 thousand in Los Altos. Zillow's home value index told a similar story as of July 31, 2026, with average values of roughly $6.04 million in Los Altos Hills against $4.60 million in Los Altos. The town with the higher total price has the lower cost per square foot. That's not a discount. It's a different set of costs, moved from the purchase price into the years you own the place.
The 200-foot rule that decides your infrastructure
Most of what separates the two cities traces back to a single technical threshold buried in the Town of Los Altos Hills' own septic bulletin: a septic permit is only issued where a sanitary sewer is not available within 200 feet of the building. Where the town's public sewer main runs close enough, you connect, and the property owner becomes responsible for maintaining the lateral, the "Y" fitting, the relief valve, and the backflow preventer from the building out to that connection. Where it doesn't, you're in the world of the Santa Clara County Department of Environmental Health, and the parcel runs on a private system for the life of the house.
That 200-foot line is why two homes a few streets apart in Los Altos Hills can have completely different ownership obligations, and why so many parcels in the hills never got connected to begin with. The terrain that makes the town's lots private and view-oriented, the same terrain that shows up in every listing photo, is largely why sewer lines never reached them.
What owning a septic system actually asks of you
A septic system isn't a one-time inspection item. It's ongoing maintenance with its own calendar. The town's guidelines call for pumping every three to five years to keep solids from reaching the drainfield, and they specifically caution against garbage disposal use, since it accelerates that buildup. Water softeners are discouraged in the area's clay soils because the sodium can alter soil chemistry and degrade drainfield performance. Even the timing of repair work is regulated: septic installation or repair is prohibited between November 1 and April 1 outside of emergencies, which means a failing system discovered in December can mean months of restricted use before permitted work can start.
None of this is disqualifying. It's routine for a large share of Los Altos Hills housing stock. But it's a maintenance line item that doesn't exist for a comparable Los Altos or Menlo Park buyer, and it belongs in the same budget conversation as property taxes and insurance.
The road is yours too
Public roads end at a lot of Los Altos Hills driveways. What continues from there is frequently a private road governed by a recorded Private Road Maintenance Agreement, administered by an elected Road Commission Agent, with maintenance and emergency repair costs split pro rata among the owners who share access. Disputes go to binding arbitration rather than court in many of these agreements. The town's own municipal code even lists specific private roads, Vinedo Lane among them, that are held open to public vehicular traffic despite private ownership, because the public would otherwise have no way to tell they aren't public streets.
Construction makes the cost of this concrete. Builders working in the hills report that private road access alone can add $30,000 to $100,000 or more to a project for the temporary widening, grading, or reinforcement heavy equipment requires, on top of another $20,000 to $60,000 for utility runs that have to travel further from the nearest public connection point. If you're planning any renovation or rebuild, the road you drive in on is part of the project budget before a shovel touches the house.
The town layers a third private-infrastructure cost on top of roads and septic: pathways. Los Altos Hills charges a development fee for its pathway easement system, calculated at $53 per linear foot of a parcel's average width, which the town notes has recently run about $11,000 for a typical parcel. It funds a network the town builds and maintains once completed, but the initial cost sits with the property owner triggering the development.
A borrowed comparison, side by side
| Los Altos Hills | Los Altos | |
|---|---|---|
| Median sale price, 3 months ending May 2026 | $5.3M | $4.2M |
| Median price per square foot | $1.66K | $1.94K |
| Median days on market, May 2026 | 15 | 10 |
| Homes sold, May 2026 | 28 | 103 |
| Sewer connection | Only if public main is within 200 ft | Standard citywide |
| Road maintenance | Often owner-shared via private agreement | Town-maintained |
The days-on-market and sale-count difference matters as much as the price gap. A market moving 28 homes a month with a 15-day median is a much thinner pool of comparable sales than one moving 103 homes at 10 days, which is part of why appraisals and pricing strategy in Los Altos Hills lean more on judgment and less on nearby comps than they do a few minutes down the road.
The ADU math changes with the lot
The one-acre minimum lot size that defines Los Altos Hills also reshapes what an accessory dwelling unit can look like there. Because parcels are larger, the town allows detached ADUs up to 1,200 square feet, provided the unit includes an on-site parking space and maintains 30-foot side and rear setbacks, a size and setback combination that simply isn't available on a standard Los Altos lot. Placement is still constrained by the town's environmental priorities: no new ADU on a slope over 30 percent, none within 25 feet of a creekbank, and none inside the critical root zone of a protected oak.
One restriction applies regardless of size. Los Altos Hills prohibits short-term rentals of both ADUs and primary residences, requiring any lease to run a minimum of 31 consecutive days. A buyer weighing a guest house as an income property should know that math doesn't work here the way it might in a different jurisdiction.
Scale matters on the main house too. The town's Estate Homes Ordinance adds design review and landscape screening requirements once an addition brings total floor area above 10,000 square feet, a threshold worth knowing before a remodel plan gets drawn.
The country club that predates the zoning
Some of this private-infrastructure culture is older than the town's incorporation. The Los Altos Golf and Country Club traces to 1923, when its founders secured 155 acres and sold the surrounding land for home sites, land that eventually became the San Antonio Hills community. San Antonio Hills, Inc., the homeowners' association that still represents that neighborhood today, formed in 1941 specifically to manage roads, parking, and the deed restrictions that came with buying land next to the club, a role it continues for roughly 1,125 homes split between unincorporated county land and the Town of Los Altos Hills. The pattern of neighbors collectively managing what a city elsewhere would maintain isn't a modern zoning quirk. It's close to a century old.
What this means if you're deciding between the two
The lower price per square foot in Los Altos Hills isn't evidence that the town is a better value. It's evidence that a larger share of what you're paying for is land and privacy rather than finished structure, and that the systems keeping the house running, sewer or septic, public road or private, aren't included in a Los Altos-style purchase the way they're assumed away elsewhere on the Peninsula. A buyer comparing the two should be pricing the parcel's systems alongside its square footage, not just its view.
Frequently asked questions
Does every home in Los Altos Hills run on well water? No. Cal Water serves Los Altos and parts of Los Altos Hills, but service varies by parcel. Confirm the specific water source, meter location, and any upgrade needs before writing an offer.
Can I rent out a Los Altos Hills ADU on a short-term basis? No. The town requires a minimum 31-day lease term for both ADUs and primary residences, which rules out Airbnb-style rentals.
How often does a septic system need to be pumped? The town's guidance calls for pumping every three to five years, more often if the household uses a garbage disposal regularly.
Is septic work available year-round? No. New septic installation or repair is prohibited between November 1 and April 1 outside of emergency situations, which can affect timelines for anyone planning work discovered during a fall or winter inspection.
If you're weighing a purchase between Los Altos Hills and a similarly priced home in Los Altos or Menlo Park, the parcel's infrastructure, not just its price per square foot, should shape the decision. Amir Delpazirian brings both a broker's read on these markets and a general contractor's eye for what a septic report, a private road agreement, or a slope condition actually means for your ownership costs. Reach out to talk through a specific address before you write an offer.
