A sewer master plan shows a trunk line reaching a parcel: how much is that map actually worth

A master plan is a planning document. It shows what the district would build if growth, money, and politics cooperate, and phasing in the outer years slips routinely because the plan gets amended every few years as demand moves.

What carries more weight, in rough order: a funded line item in the current capital improvement program with a bond or rate revenue behind it, an executed developer agreement where somebody upstream has committed to build and dedicate infrastructure, and treatment capacity at the plant that serves that basin. A district can want to extend service and have no headroom at the plant, which stalls everything regardless of what the pipe map shows. Ask the district engineer directly for current uncommitted capacity and for what's already reserved by pending projects. They will usually tell you.

Annexation is the other gate and it's discretionary. In most states a city chooses whether to annex and on what terms, and the rules for how and whether it can happen at all differ by state, so check your state's statute and the city's own policy rather than assuming. Some parcels get service without annexation, some can't.

One cost people underprice: even when the line arrives, connection isn't free. Impact fees, capacity fees, and the cost of extending from the trunk to your boundary can run into real money per lot, and those fees generally rise over a fifteen year hold. If your entry price already assumes utilities, you've paid for them twice.

The honest position on a parcel like this is that the map improves your odds and guarantees nothing. Size the position so a ten year slip doesn't hurt.

Call the district engineer and ask the capacity question directly. They are usually completely open about it, and it is common to hear that the basin is effectively full until a plant expansion nobody has funded yet. A ten minute call like that can change the whole read on an area.

Half a million tied up with no rent coming in for a decade or more. The thesis is understandable, and the hard part is living with the carry for that long.

$496k at 8% opportunity cost is roughly $40k a year of foregone return, before taxes on the parcel. Over twelve years that compounds past the purchase price. So the exit has to be a multiple, not a nice premium. Anchor, does your underwriting say what price per acre a builder would actually pay once the pipe is in? That number is the whole deal and it's the hardest one to get.