Last reviewed: October 24, 2026. General information only, not legal, engineering, or tax advice. Each Canandaigua Lake town adopted its own version of the watershed’s model septic law, and zoning differs town by town. Confirm requirements with your town code office and the Canandaigua Lake Watershed Inspector before you design or buy.
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A lot of the houses around Canandaigua Lake started life as summer cottages: a few small bedrooms, a porch, a shallow crawl space, water lines that were drained every fall, and a septic system sized for July weekends. Turning one into a home you can live in through January is very doable, and plenty of owners have done it. But on this lake, the project runs into a set of rules that most lakes do not have, because Canandaigua Lake is a public drinking water supply.
This guide walks through the order of operations for a seasonal-to-year-round conversion on Canandaigua Lake: zoning, the septic review that the watershed’s model law ties to bedrooms and square footage, building permits, water supply, heat and winter access, and the tax and insurance changes that follow a move from second home to primary residence. For the general building science of a conversion (insulation, air sealing, moving water lines inside the heated envelope), our sister site has a detailed seasonal cottage conversion guide for Keuka Lake; most of it applies here too. This guide focuses on what is specific to Canandaigua.
Step 1: Find out which town, and which zoning district
Canandaigua Lake’s shoreline is split among several towns in Ontario and Yates counties. The Watershed Council’s septic workgroup included the Towns of Canandaigua, Gorham, Middlesex, Italy, Naples, and South Bristol. Each town writes its own zoning law, and each decides how to adopt the watershed’s septic model law. Your tax bill or the county parcel viewer, not the mailing address, tells you which town has jurisdiction.
Example: the Town of Canandaigua’s Residential Lake District
To show the kinds of rules that matter, here is what the Town of Canandaigua zoning code says about its RLD Residential Lake District (Town Code § 220-21). Other towns use different district names and numbers.
- Purpose. The district exists “to allow limited residential uses that protect the quality of Canandaigua Lake and the surrounding natural topography, including the shoreline, ridgelines, and scenic vistas.”
- Permitted principal uses. One single-family dwelling per lot, or one single-family dwelling plus one attached or detached accessory dwelling unit, along with public parks and public safety facilities.
- Small, older lots. Preexisting nonconforming lots under 20,000 square feet have their own setbacks. On lots under 10,000 square feet, principal structures need a 50-foot front setback, 30-foot rear setback, and 8-foot side setbacks, with maximum building coverage of 25 percent and lot coverage of 40 percent. On lots between 10,000 and 20,000 square feet, it is 55 feet front, 30 feet rear, and 10 feet on each side, with 20 percent building coverage and 30 percent lot coverage.
- Rear setbacks are measured from the mean high-water mark, which for a lakefront lot means the lake side.
- Accessory buildings. One detached garage no taller than 16 feet and one attached garage may be permitted, plus one accessory building up to 100 square feet and 10 feet high. No accessory buildings may go in rear yards adjoining the lake.
- Erosion control. Erosion and sedimentation controls must be used before, during, and after construction until ground cover is reestablished, under the town’s Chapter 165.
- Teardowns. For bisected lots, the code’s lot coverage rule for the lakefront portion exempts tear-down-and-rebuild projects that keep the same building coverage percentage and do not increase a preexisting nonconformity.
The practical point: many cottages sit closer to the lake or the road than current setbacks allow. Adding a bedroom wing, a second story, or an attached garage can trigger a variance, and an enclosed porch can count as building coverage. Talk to the town zoning officer with a sketch before you hire an architect. Our Canandaigua Lake dock rules guide covers the separate waterfront rules.
Step 2: The septic review is the heart of a Canandaigua conversion
Year-round use means the septic system works every day, all winter, instead of on summer weekends. On Canandaigua Lake, adding bedrooms or space can also trigger a formal inspection and upgrade requirements. Three layers of rules apply; our Canandaigua Lake septic inspection guide explains them in depth. Here is how they hit a conversion.
The state watershed rule
New York’s sanitary code has a section written for this lake, 10 NYCRR § 132.1. Among other things, it requires written permission from the watershed authority, with plans and a percolation test, before installing, repairing, or replacing a septic system in the watershed, and sets a minimum capacity of 500 gallons for any new or replacement septic tank.
What the model law says about conversions
The Canandaigua Lake Watershed Council’s Model Onsite Wastewater Treatment System Law (final draft, December 2016) is the template most lake towns worked from. Under it, it is unlawful to do any of the following without first having the system inspected by a Certified Inspector (a registered OTN inspector or a licensed Professional Engineer):
- undertake a change of use;
- convey the property;
- increase the number of bedrooms or bedroom equivalents;
- increase the building’s square footage by more than 25 percent; or
- alter the building so the work area exceeds 50 percent of the existing building’s area.
A seasonal-to-year-round conversion often hits two of these at once. Finishing an attic or converting a sun porch into a bedroom adds a bedroom; a full gut renovation of a small cottage can easily exceed 50 percent of the work area.
The model law’s “change of use” definition is aimed at changes likely to increase hydraulic loading, and its examples are commercial-to-residential style changes. It does not list seasonal-to-year-round occupancy as an example, and the authority having jurisdiction decides whether a given change increases loading. Ask your town and the Watershed Inspector how they treat it before you assume either way.
What counts as a bedroom
The model law defines a “bedroom and/or bedroom equivalent,” for septic sizing, as a room with features characteristic of bedrooms, generally including reasonable access to a full bathroom on the same floor, an adequate means to close the room off for privacy, and/or a minimum of 70 square feet. In plain terms, calling it a “den” or “office” does not settle the question. If a room could be a bedroom, expect it to be counted as one.
How a new or upgraded system is sized
Under the model law, new or modified systems must be designed by a Design Professional (who may contract with the Ontario County Soil and Water Conservation District’s Uniform Inspection Procedures Program for site and soil work). Systems under 1,000 gallons per day follow the state’s Appendix 75-A design standards. The minimum design is:
- 130 gallons per day per bedroom for systems more than 200 feet from the lake; and
- 150 gallons per day per bedroom for systems within 200 feet of the lake.
House size counts too. The model law sets these design loads, whichever is larger:
| Bedrooms or heated living space | Design as |
|---|---|
| Up to 2 bedrooms or up to 1,200 sq ft | 2 bedrooms (also the minimum) |
| 3 bedrooms or 1,201–2,250 sq ft | 3 bedrooms |
| 4 bedrooms or 2,251–3,300 sq ft | 4 bedrooms |
| 5 bedrooms or 3,301–4,050 sq ft | 5 bedrooms |
| More than 5 bedrooms or over 4,050 sq ft | add 110 gpd per additional bedroom |
That square-footage column matters for conversions. A two-bedroom cottage that grows past 1,200 square feet of heated living space can be sized as a three-bedroom house even if the bedroom count stays the same, because the space you heat for year-round use is what counts.
Lakeshore lots and the ten-year flood line
The model law defines Canandaigua Lake’s edge at the mean high water level of 689.40 feet and sets a ten-year flood elevation of 690.00 feet. Among its listed failure conditions: an absorption area within 100 feet of the lake with the bottom of the leach line at or below 690.00 feet. Systems within 200 feet of the lake also face periodic inspection and specific requirements for substandard systems. Other rules that affect where you can put an addition, a driveway, or a sump discharge:
- nothing may be placed on the absorption area, including buildings, paving, fill, or parking; and
- roof, cellar, foundation, and storm drainage may not be discharged into the septic system.
If your conversion adds a sump pump or new downspouts, route them away from the septic system and the leach field.
Paying for an upgrade
New York’s Septic System Replacement Fund has covered part of the cost of replacing failing systems in eligible areas; our septic guide links the current program outline and explains who to ask. Never assume a grant before your contract is signed.
Step 3: Building permits and the state code
Nearly everything in a conversion, from structural work and new rooms to heating systems, chimneys, plumbing, and electrical, needs a building permit from the town under the New York State Uniform Fire Prevention and Building Code and the Energy Conservation Construction Code. The Department of State’s Division of Building Standards and Codes publishes the current codes. Work through the code office early on:
- Which parts must meet current energy code. In general, new work and altered parts of a building must meet current code, not necessarily the whole house. Ask how your project scope is treated.
- Smoke and carbon monoxide alarms required for the work you are doing.
- Egress windows for any new or converted bedroom.
- Heating appliance permits and chimney work. Wood stoves and new fuel-burning appliances usually need inspection.
- The certificate of occupancy or completion you will need for insurance and any future sale.
The building permit and the septic review are connected. In a town that adopted the model law, adding bedrooms or enough square footage requires the septic inspection first, so ask the code office how the two reviews fit together and start both at the same time.
Step 4: A year-round water supply
Many cottages pull water straight from the lake with a summer-only line. The NYSDOH says that if you are not on public water and use surface water, bloom or no bloom, never drink, prepare food, or make ice with untreated surface water, and during a bloom do not use it for those purposes even if you treat it yourself. A lake intake needs treatment and freeze protection to be a reliable year-round supply. Our guide to Canandaigua Lake drinking water and algal blooms covers intakes, public water, and the NYSDOH harmful algal bloom guidance. Your options are usually:
- connect to public water if a town or city line reaches your road;
- drill a well where geology and setbacks allow; or
- keep a lake intake with a buried, frost-protected line, a heated pump space, and a treatment system designed for surface water.
Moving a supply line below frost depth, or into heated space, is one of the biggest line items in a conversion. Get it priced before you commit to a budget.
Step 5: Heat, insulation, and moisture
A cottage that has never been heated in winter usually needs a real heating system, insulation, and air sealing, and the order matters. Seal and insulate first so you can size the heating system for the house you will have, not the drafty one you have now. Our Canandaigua Lake home heating costs guide compares propane, heating oil, heat pumps, and wood, and lists state programs that can help pay for efficiency work.
Moisture is the hidden risk. Insulating and tightening an old cottage without managing moisture and ventilation can trap water in walls and crawl spaces. Before you close up walls, read our sister site’s guide to mold, damp basements, and crawl spaces, which explains New York’s mold licensing law and the humidity targets health agencies recommend.
Step 6: Winter access and daily life
A cottage road that is fine in August may not be plowed in February. Before you commit to year-round living, confirm who plows your road and driveway, whether a private road has a maintenance agreement, and how long the drive is to work, school, and groceries in snow. See our guide to winter plowing and driveways around Canandaigua Lake.
Step 7: Taxes and insurance once it is your home
- STAR. New York’s STAR program is for a primary residence. If the cottage becomes your home, you may become eligible; if you keep a primary residence elsewhere, you are not. See our Canandaigua property taxes and STAR guide.
- Assessment. Additions, finished space, and new systems can change a property’s assessed value. Budget for a higher tax bill after a major conversion.
- Insurance. A seasonal or secondary-home policy may not fit once you live there full time. Tell your agent before the change in occupancy, and ask about water damage, frozen pipes, and sewer backup coverage. Our sister site’s lake home insurance guide explains the questions to ask.
A conversion checklist
- Confirm your town, zoning district, and setbacks with the zoning officer.
- Ask the town and the Watershed Inspector how they will review your septic, and schedule the inspection early.
- Hire a Design Professional if the system must be upgraded or replaced.
- Settle the water supply plan and price freeze protection.
- Get building permits; plan insulation, air sealing, ventilation, and heat together.
- Line up plowing and a winter access plan.
- Update insurance and, when eligible, apply for STAR.
What to have on hand
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- A Wi-Fi freeze alarm and temperature monitor to warn you if the heat fails during the first winter
- Foam pipe insulation for supply lines in crawl spaces and exterior walls
- Combination smoke and carbon monoxide alarms (confirm with your code officer which types your project requires)
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Frequently asked questions
Do I need a septic inspection to convert a Canandaigua Lake cottage to year-round?
Often, yes. Under the watershed’s model septic law, which most lake towns adapted, an inspection by a Certified Inspector is required before adding bedrooms or bedroom equivalents, increasing square footage by more than 25 percent, or altering more than 50 percent of the building. Check your town’s version.
What counts as a bedroom for Canandaigua Lake septic sizing?
The model law treats a room as a bedroom or bedroom equivalent based on features such as reasonable access to a full bathroom on the same floor, a way to close it off for privacy, and/or at least 70 square feet. Calling it an office does not settle the question.
How big does a new septic system need to be near Canandaigua Lake?
The model law sets a minimum design of 130 gallons per day per bedroom more than 200 feet from the lake and 150 gallons per day within 200 feet, with a two-bedroom minimum. House size also counts: over 1,200 square feet of heated space is sized as three bedrooms.
Can I keep drinking water from a lake intake year-round?
Only with treatment and freeze protection. NYSDOH says never to drink, prepare food, or make ice with untreated surface water, and not to use surface water for those purposes during a bloom even if you treat it yourself. Public water or a well may be better options.
Do I need a building permit to winterize and convert a cottage?
Most conversion work, including structural changes, new rooms, heating systems, plumbing, and electrical, needs a town building permit under the NYS Uniform Code and Energy Code. Ask the code office which parts must meet current code and what alarms and egress windows are required.
Will converting my cottage change my property taxes?
It can. Additions, finished space, and new systems can raise the assessment. If the house becomes your primary residence, you may become eligible for STAR, which is limited to primary residences.
Official sources
- Canandaigua Lake Watershed Council: Model Onsite Wastewater Treatment System Law (PDF, December 2016)
- Canandaigua Lake Watershed Council: regulation
- Ontario County SWCD: Canandaigua Lake Watershed program
- 10 NYCRR § 132.1: Canandaigua Lake watershed rules
- Town of Canandaigua Code, Article V District Regulations (RLD § 220-21)
- NYS Department of State: Building Standards and Codes
- NYSDOH: Harmful blue-green algae blooms and drinking water
Related on Living on Canandaigua: Septic inspections · Home heating costs · Drinking water and algal blooms · Winter plowing · Property taxes and STAR · Dock rules
Across the network: Practical Finger Lakes septic basics · Living on Keuka: converting a seasonal cottage
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