Texas · November 21, 2023
What a Texas Freeze Does to Stored Water
Water expands nine percent. A brimful container has nowhere to put it, and the shoulder is where it gives.
The short version
Leave headspace through winter, drain exposed plumbing, close valves rather than trusting a hose bib, and keep a small reserve of sealed containers racked and empty — you cannot buy them the week you need them.
Central Texas freezes are short, hard and increasingly consequential. They also arrive with enough warning that most of the damage they do to stored water is avoidable, and every February we take calls from people discovering that it wasn't.
The physics, briefly
Water expands roughly nine percent when it freezes. That's not a small allowance — on a 275-gallon container it's about twenty-five gallons of volume that has to go somewhere.
A container filled to the shoulder has room. A container filled brimful does not, and the expanding ice does what expanding ice does. It splits, and it almost always splits at the shoulder, where the wall geometry changes and the stress concentrates.
| Fill level | Freeze outcome |
|---|---|
| Brimful | Split at the shoulder. Container lost. |
| To the lid | Likely bulge, possible split. |
| To the shoulder | Ice forms upward into the headspace. Container survives. |
| Three-quarters | Comfortable margin. What we recommend through winter. |
The plumbing goes first
Before the bottle splits, the exposed fittings do. A valve full of water, a length of hose, a pump housing — all of them hold a small volume with nowhere to expand, and all of them crack.
- Drain hoses completely and store them somewhere they can't refill from condensation.
- Drain pumps. Diaphragm pumps in particular hold residual liquid and crack their housings.
- Close the outlet valve. Don't rely on a downstream hose bib to hold — if it splits, the valve is all that's between you and an empty container.
- Cap the outlet after the valve. Two barriers rather than one.
- Insulate any run of pipe you can't drain.
Where the container sits
Thermal mass is on your side. Two thousand three hundred pounds of water takes a long time to freeze through, and a short overnight freeze often doesn't reach the core at all.
What kills containers is a multi-day event where the temperature never recovers above freezing. In those, a container in the open on a north-facing wall is in a materially worse position than the same container against a south wall or under a structure. Small siting decisions buy real margin.
Emergency water, and the timing problem
The February 2021 event emptied our yard in four days. Water containers went out to communities, contractors and neighbours faster than we could wash them, and we ran out.
The lesson we took from it is that emergency water storage cannot be organised during an emergency. Everyone wants the same thing in the same week, the supply is finite, and the freight network is precisely as disrupted as everything else.
We now hold a reserve tier specifically for weather events. It's still first-come during an actual event, which is why operations that want guaranteed access set up a standing reservation instead.
What a sensible reserve looks like
| Situation | Reserve | Notes |
|---|---|---|
| Household | 1 × 275 gal, rebottled | Drinking and sanitation for several days |
| Small crew or shop | 2 × 275 gal | Sealed, stored empty, filled when a warning issues |
| Facility | Size against headcount and expected outage | Rebottled units; potable path matters |
| Livestock operation | 12–20 gal per head per day | The number that surprises people most |
Store them empty and sealed. A full container in storage is a freeze risk of its own; an empty sealed one fills in twenty minutes when a warning issues and carries no risk in the meantime.
And the summer half of the same problem
The same headspace discipline applies in reverse. A container filled brimful in April and left in open Texas sun will weep, bulge or vent by August as the liquid expands with heat. Fill to the shoulder year-round and both problems disappear.
Published November 21, 2023 · Filed under Texas
