Propane Refill Planning for a Multi-Day Coast Outage

September 7, 2026

Sizing the tank is the easy half. The half that decides whether the lights stay on through day five is the refill nobody can promise you.

The plan usually assumes a delivery that never arrives

Fuel planning on the Mississippi Coast tends to stop at the tank. A homeowner picks a size, fills it in June, and treats the gauge as the answer. The part that gets skipped is the refill. What happens on day four, when the tank reads low, the roads north are cut, and the supplier is working through a few hundred calls with trucks that cannot get everywhere they are needed?

The hurricane generator runtime guide on this site puts the working planning number at seven days of outage, sitting inside a typical Coast restoration window of five to ten days. That number is more useful read as a fuel requirement than as an inconvenience. It is how much propane needs to already be sitting on the property when the wind stops.

What the tank actually holds

Nominal tank size is not usable fuel. Liquid propane expands as it warms, so a tank is filled to leave vapor space above the liquid, and the usable figure runs meaningfully below the number on the side of the tank. Runtime then follows from usable gallons and burn rate, which for a whole-home standby in the 20 to 26 kilowatt range is roughly two to three and a half gallons of propane per hour.

Set against the seven-day planning number, the arithmetic is blunt:

• A 120-gallon tank holds about 96 usable gallons, which is roughly one to two days of continuous running.
• A 250-gallon tank holds about 200 usable gallons, or roughly two and a half to four days at heavy load and five to six days with load management.
• A 500-gallon tank holds about 400 usable gallons, or roughly five to eight days of continuous running.

Deliveries stop before the storm does, and restart late

Propane does not move during a hurricane. Suppliers pull trucks off the road well ahead of landfall, and the window for a top-off closes earlier than most people expect, usually while the forecast cone is still wide enough that plenty of households have not decided to act.

Afterward, delivery depends on conditions that have nothing to do with an individual account. Roads have to be passable, debris has to be cleared, and the bulk plant itself needs power to pump. The scale involved is easy to underestimate: at Hurricane Zeta's peak in October 2020, 234,975 Mississippi customers were without power, according to U.S. Department of Energy situation reporting, and Hurricane Ida later peaked near 148,850 customers in the state. A propane distributor is working a restoration map, not a queue.

The practical conclusion is to treat the refill as a bonus rather than a step in the plan. Whatever is in the tank when the storm makes landfall is, for planning purposes, the whole supply.

Load management buys more days than a phone call

The cheapest additional runtime does not come from a bigger tank. It comes from asking the generator to carry less. Shedding a second air-conditioning compressor, a pool pump, or an electric water heater during the worst of an outage changes the burn rate directly, and the runtime guide puts the effect at roughly 30 to 50 percent added to every tank figure above.

That turns a 250-gallon tank from a three-day proposition into something that can plausibly cover a restoration week. Whether a given house can do it depends on how the loads are grouped and what the transfer switch is set up to drop, which is decided during a generator sizing and load assessment rather than improvised in the dark on day three.

The plan to have in place before June

Most of this work is off-season work, and it is easier to do when no storm is named. Find out the tank's usable capacity rather than its nominal size, so the runtime math starts from a real number. Ask the supplier directly what the storm cutoff policy is and how far ahead of landfall deliveries stop. Keep the tank high from the start of the season instead of topping it off on a forecast, because that is precisely when everyone else is calling.

Any tank siting, fuel line, or regulator work belongs in the same off-season window, and it is regulated territory. Clearances, tank placement, and connection requirements vary by jurisdiction along the Coast, so confirm what applies at a specific address with the local authority having jurisdiction before anything is set. The propane and natural gas fuel hookup side of an installation is not a detail to settle in August.

Anyone setting up standby power for a Gulfport or Biloxi home for the first time should settle the fuel question before choosing the generator, not after. Tank size, load plan, and unit size are one decision, and the outage record on this coast is the reason they have to be made together.

More from the blog

• Oil Changes and Generator Service During a Multi-Day Outage
• Whole-Home or Managed-Load: What Your Transfer Switch Decides
• What Saltwater Flooding Does to a Generator, and When a Unit Cannot Be Salvaged