Waxhaw's Sewer Plant Is Nearly Full, and the Homes It Already Promised Are Still Coming

The Twelve Mile Creek Water Reclamation Facility treats wastewater for Waxhaw, Weddington, Wesley Chapel, Indian Trail, Stallings and parts of Marvin. As of the 12-month rolling average through August 2026, Union County Water reports that 89.8% of the plant's 7.5 million gallons per day of permitted capacity is used.

Waxhaw's sales data shows something else. In September 2026, the town's median sales price was $655,000, down 6.4% from September 2025. Inventory rose 9.0% to 279 homes, and months of supply moved up to 3.5, according to Canopy Realtor Association's September 2026 local market update. Both facts are accurate. The way the county counts sewer capacity explains how they fit together.

"Used" Mostly Means Promised

Union County Water measures capacity as the gallons actually flowing through the plant plus the gallons it has already committed to projects that aren't connected yet. Those are two very different kinds of "used."

About 1.6 million gallons a day is reserved for approved projects whose homes and buildings aren't sending wastewater to the plant yet. That reserve is the important number. It covers new construction that is already approved and moving toward completion, and none of it has to compete for the remaining 0.765 MGD.

The headline percentage has also barely changed. A 2024 post on The Waxhaw Wall, a local blog, cited the county's figure for the plant at the time as 90.6%. So the share in use has stayed at roughly nine-tenths for about two years.

How a Neighborhood Gets Its Gallons

The allocation process explains why approved projects are safe and new proposals are not. Union County Water says it does not issue "will serve" letters. Under the county's utility ordinance, a project moves through these steps:

1. Plan review by Union County Water, followed by the required permits and easements.
2. An executed and recorded extension agreement. The ordinance makes this agreement the only way capacity is allocated.
3. A five-year reservation of that capacity under the standard agreement. A developer can get one additional three-year extension if fees for the entire phase have not been paid within the initial five years, the infrastructure is accepted within five years, fees have been paid on at least half the lots, and the developer applies at least 60 days before expiration.
4. System development fees for each lot, due when that lot's building permit is applied for.

A neighborhood with a recorded agreement holds its gallons for years. A neighborhood still in early review holds nothing, and the uncommitted pool it would draw from is now under 0.8 MGD for the whole basin.

What Promised Gallons Look Like as Houses

State rules give a way to turn gallons into homes. Under 15A NCAC 02T .0114, a utility can calculate flow for new homes on shared sewer systems at 75 gallons per day per bedroom, so a three-bedroom home counts as 225 gallons.

On that basis, the 1.609 MGD committed but not yet flowing works out to roughly 7,150 three-bedroom equivalents across the basin. The 0.765 MGD still uncommitted works out to about 3,400. Treat both numbers as rough estimates. The commitments cover several towns and include commercial users, and actual allocations depend on each project's design. They do show the relative size of the two pools, though. The homes already approved and on their way outnumber the homes that could still be approved before the expansion.

In Waxhaw, the town's developer projects tracker shows where the town's larger projects stand:

• Adelina, Phase 1: 486 units of single-family and mixed-use development on Providence Road S, between Gray Byrum and Sunset Hill Roads, listed as under construction. The applicant is Shea Homes of the Carolinas.
• Adelina, Phases 2 and 3: 144 single-family homes and 108 attached townhomes at the same location, in staff review.
• Yarbrough Farm: 485 single-family homes and townhomes at 7715 Waxhaw Highway, at the pre-construction meeting stage.
• Overlook at Waxhaw: 92 single-family homes at 0 Rehobeth Road, in preliminary plat review.

Adelina Phase 1 and Yarbrough Farm together account for 971 units listed as under construction or at the pre-construction stage. Adelina Phases 2 and 3 are still in staff review, and Overlook is at the preliminary plat stage. Under the county's process, capacity is allocated only once plans, permits and a recorded extension agreement are in place. The town notes on the tracker that dates and unapproved plans can change.

Why Resale Numbers Soften While the Plant Fills

New homes that already have capacity reach the market over several years, and every finished one adds to what resale sellers compete against. Waxhaw's 2026 numbers match that picture. Year to date through September, new listings rose 4.6% to 1,112 and pending sales rose 3.9% to 795. The year-to-date median fell 3.7% to $698,500. Canopy's figures don't separate new construction from resale, so the data can't prove how much builder product is driving the trend. It does show that buyers had more homes to choose from this year.

Waxhaw's supply is rising faster than the county's, and its prices are easing while the county's held flat. Homes are not sitting longer, though. In September 2026, Waxhaw homes that sold spent 42 days on market until sale, compared with 65 a year earlier. Buyers are still buying. They're paying a bit less because they have more options. Monthly figures for a town with 74 closings in September can swing a lot, which is why the year-to-date column is the better guide.

A buyer comparing Waxhaw with other south-Charlotte suburbs can read this as a window. Through 2026 and into 2027, choice comes from neighborhoods that already secured their sewer capacity. A seller pricing a resale home is competing with those same new neighborhoods, and the 3.5 months of supply reflects that.

September 2027 Adds Capacity, but Doesn't Say Where It Goes

The expansion to 9.0 MGD began in January 2025 and is scheduled to finish in September 2027, according to Union County's 2025 Local Water Supply Plan filed with the state. That adds 1.5 MGD, about 6,700 three-bedroom equivalents at the state's design rate. All six communities served by the plant will draw on it.

No published plan explains how the new capacity will be divided. Stallings offers one reference point. A March 2026 Stallings staff report estimated the town's share of the expanded basin at about 97,000 gallons per day. Its council chose not to pursue more capacity and backed a policy toward privately maintained treatment systems for developments Union County's system can't serve. Union County also has a 1996 agreement with Charlotte for up to 3 MGD of capacity at the McAlpine Creek plant. In 2025 the county sent an average of 1.852 MGD through it.

As a result, the expansion buys time for the basin rather than opening it up. Neighborhoods approved before 2027 keep their reserved gallons. Proposals after that will compete for a share of 1.5 MGD with five other communities.

Quick Answers

Does the near-full plant mean no more new homes in Waxhaw? No. Capacity already committed under recorded extension agreements stays reserved, and Adelina Phase 1 and Yarbrough Farm together list 971 units under construction or at pre-construction. The constraint applies to projects that haven't secured capacity yet.

Is the water supply the same constraint? No, it's a separate system. The county's water distribution draws on the Catawba River and Yadkin River water treatment plants, and Yadkin water entered the system on February 13, 2024. The Stage 2 conservation restrictions posted on the county's site are drought-use rules and are not tied to sewer allocation.

Where can I check the latest capacity figure? Union County Water posts the table on its wastewater capacity page, updated monthly about four to six weeks after the data is collected.

This post explains public rules in general terms and isn't legal, tax or financial advice. If a decision depends on a utility agreement or ordinance, confirm the details for your property with the right professional.

If you're weighing a resale home against new construction in Adelina or Yarbrough Farm, or you're deciding when to list before more new neighborhoods come online, Nelvia Bullock and Bullock & Co. can walk you through how Waxhaw's pipeline affects your timing and price. Let's talk about your next move.