How much room does Wilton have left to add apartments? According to the town's own figures, the meters at the Norwalk line have never recorded more than 550,000 gallons a day in the last four years. The town's planning worksheet, which adds up every approved and pending project, shows 650,811 gallons a day committed. That is 811 gallons more than Wilton is allowed to send.
If you are a buyer who has heard that Wilton Center is about to fill with new apartments and townhouses, that 100,000-gallon gap explains more than any rendering. Whether Wilton gets more apartments, condos and smaller homes over the next few years depends on a flow formula and a contract with a neighboring city. Zoning hearings come later in the process.
A contract line, measured with a formula
Wilton sends its wastewater to Norwalk under a 2010 interlocal agreement between the two towns' water pollution control authorities. According to the WPCA's October 2026 sewer capacity presentation, the agreement caps Wilton at 650,000 gallons per day. When the Wilton WPCA met on Sept. 23, 2026, GOOD Morning Wilton reported that actual flow averaged about 484,000 gallons a day, up from 464,000 in June. Projected flow passed the contractual limit for the first time.
The gap exists because the WPCA tracks commitments with a calculation. It does not wait for meter readings. The same list of projects comes to very different totals depending on the formula:
| How the flow is counted | Gallons per day | Against the 650,000 cap |
|---|---|---|
| Highest measured flow to Norwalk, last four years | 550,000 | Under |
| Committed and pending, at 65 gallons per person | 650,811 | 811 over |
| Same list, at 150 gallons per bedroom | 763,647 | 113,647 over |
The 650,811 total is not raw demand. It starts from the 550,000-gallon measured high and subtracts a 172,000-gallon credit for leak repairs. It then adds 30,730 gallons held for vacant properties, about 61,896 for projects under construction, 143,467 for approved projects not yet built and 36,718 for pending applications and pre-applications. Changing any of those inputs changes how many apartments fit.
The gallons-per-person rule became official in August
This calculation decides the outcome, and its key input was settled recently. The WPCA debated how to count apartment flow through 2024 without voting on it. On Aug. 19, 2026, it adopted item 5 of Appendix V of its regulations. The rule sets multifamily flow at 65 gallons per person per day, with occupancy of 1.47 people for a one-bedroom, 2.12 for a two-bedroom and 2.94 for a three-bedroom unit.
The 150-gallons-per-bedroom figure is the state septic standard. It assumes two people per bedroom at 50 gallons each, multiplied by a 1.5 safety factor. The WPCA's view is that applying it town-wide overstates flow and limits capacity for no reason, though the town still uses it to size pipes. Developers have pushed for less. In June, GOOD Morning Wilton quoted First Selectman Toni Boucher describing applications that "may want to use 55 gallons per bedroom instead," calling it "a range of opinion when it comes to flow."
Under the adopted rule, Wilton counts 96 gallons a day for a one-bedroom apartment, 138 for a two-bedroom and 191 for a three-bedroom. The town's comparison of four unnamed area towns shows per-unit figures of 140 to 167 gallons for a one-bedroom. Even so, Wilton is the one that is out of room, at 85% measured use. The town's presentation explains the difference: the other towns measure against their own treatment plants, and Wilton measures against its contract with Norwalk.
So Wilton already uses one of the leaner formulas in the comparison and is still full on paper. The remaining options are more capacity from Norwalk, recovered capacity, or saying no.
Norwalk has said no twice
Raising the cap would end the problem, but Norwalk has not agreed to it. GOOD Morning Wilton reported that Boucher described Norwalk's responses to two earlier requests as cordial and amicable, but firm that an increase is not an option.
"If we're at the limit, we're at the limit. That's the bottom line. There's no wiggle room there."
The WPCA agreed in September to ask Norwalk again, since the numbers had now reached the limit. The town's own October presentation flags a catch even if Norwalk agrees. New capacity "would likely draw more large apartment applications and be used up quickly."
Where each named project stands
Since the cap is fixed, every project competes for the same last gallons. Here is where the projects stand as of this month:
- Kimco, 15–21 River Rd., Wilton Center Phase II. Kimco proposes 225 apartments. It asked for 17,532 more gallons a day, which would take the combined Phase I and II allocation from 33,748 to 51,280. Kimco argued that removing a 2009 allocation for 24 Cannon Road and using its own flow assumptions would leave room under the cap. That 24 Cannon Road allocation never went to Planning and Zoning and is marked as potentially expired. The WPCA took no action in September and sent the materials to staff and its consultant for review. Phase II was back on the agenda for a review update on Oct. 14. Kimco's attorney has said the company is pursuing permits for Phase I.
- Baywing LLC, 19 Cannon Rd., Cannondale. A Connecticut appeals court overturned the WPCA's 2023 rejection in May. On Sept. 23 the WPCA voted 6-0 to approve a court-ordered sewer extension and a 15,300-gallon allocation for the proposed 70-unit building. The approval includes a flow meter requirement and 15 special conditions. Baywing's representative said no Planning and Zoning application had been filed yet.
- Belden Hill Road senior living, 329/331/345 Belden Hill Rd. The WPCA has approved it with conditions, and it is counted at 19,981 gallons a day. It is not under construction. GOOD Morning Wilton reported that Hines withdrew its 280-unit application for the former School Sisters site effective Oct. 5. The town's Planning and Zoning list now shows a 208-unit senior living pre-application for the same addresses, with documents dated Oct. 13.
- CHEL Associates, 33 Danbury Rd. The town's current Planning and Zoning applications list shows it as site plan application SP#541, for six second-floor residential units and two first-floor restaurants, with documents dated Oct. 27. The September sewer worksheet counted it at 658 gallons a day.
The town's figures show the trade-off clearly. One apartment building with more than 200 units needs about 25,000 gallons a day, roughly 4% of Wilton's entire limit. Multifamily projects make up about 146,000 of the 242,000 gallons of new flow in the pipeline, or about 60%.
Wilton Center is third in line
When capacity is scarce, the WPCA does not hand it out first-come, first-served. Its priority policy ranks areas in this order:
- Priority businesses in Wilton
- The train-station transit-oriented development district
- Wilton Center
- Danbury Road
The October presentation lays out three paths. The first is to hold the line, which protects remaining capacity for existing residents, businesses and the priority areas. The second is to seek more capacity from Norwalk. The third is to recover capacity through leak repairs and expired allocations, which takes time and money. On the first path, the presentation notes that each large apartment building "uses capacity that can't be reclaimed once it is built," and that holding the line has to be applied evenly under WPCA rules.
Vacant buildings make the accounting harder. A vacant building keeps its allocation, held in reserve. In June, GOOD Morning Wilton reported that the reserve for vacant properties rose by nearly 21% after the town began counting Kimco's 110,800-square-foot office building at 15 River Rd., whose tenants had announced they were leaving. Boucher explained at the time that the problem comes when a new use needs more than the old one was allowed.
What buyers are choosing from while this plays out
Most of what you can actually buy in Wilton today is single-family housing, and the market for it cooled in October. According to an October 2026 brokerage market report, Wilton recorded 14 single-family sales that month, down 33.3% from October 2025. The median sold price was $1.1 million, down 17.8% from a year earlier, while the average held at $1.4 million. Average days on market rose to 37 from 23, and homes sold for 101% of asking, down from 104%. Single-family inventory stood at 64 homes, compared with 61 a year earlier.
October's condo and co-op inventory was 11 units, up from eight. That small number is the base the Kimco, Baywing and Belden Hill projects would add to. For buyers weighing Wilton against towns where more apartments or condos are coming, the timing of that extra supply now depends on WPCA votes on allocations, Planning and Zoning approvals that come after them, and any response from Norwalk.
Quick answers
Does Wilton's sewer cap affect homes already connected? The WPCA describes holding the line as a way to protect capacity for existing residents and businesses. The cap matters most for new or larger uses.
What will sewer service cost in 2027? In June the WPCA approved a 2.7% increase for 2027, to $300 per unit from $292, according to GOOD Morning Wilton.
Where can I follow the decisions? The Wilton WPCA's agendas and minutes are posted on the town website, including the flow worksheets staff present at each meeting.
When the next allocation vote changes what Wilton Center will look like, it changes how buyers compare homes near it. If you own in Wilton and want to know how today's market and the pipeline of new projects affect your home's value, Taylor Tait will prepare a complimentary home valuation using current Wilton sales and town data.
