LOG-020 ·
Water: The Dependency I Almost Skipped
The household audit's most embarrassing omission. One pipe, one utility, zero buffer, and the numbers that fixed it for $412.
- Words
- 713
- Est. read
- 3.1 min
- Confidence
- 0.90
- Topics
- water, resilience, audit
The original household audit graded sixteen systems and I have been working through the findings in public. Here is a confession the log requires: water was not on the original list. The single input without which the household fails in 72 hours, and the auditor forgot it, because it has never once failed him. This is precisely the blindness the audit exists to correct, so consider this entry both a remediation and a demonstration of why "it has never failed" is the most dangerous sentence in resilience planning. I have said that about DNS. It is truer about water.
The baseline, measured
First, consumption. A flow logger on the main line for 30 days, plus meter readings:
| Use | Liters/day (household) | Share |
|---|---|---|
| Toilets | 128 | 24% |
| Showers and baths | 121 | 23% |
| Laundry | 87 | 16% |
| Irrigation (June) | 84 | 16% |
| Faucets and dishwashing | 76 | 14% |
| Drinking and cooking | 11 | 2% |
| Losses and misc | 27 | 5% |
| Total | 534 |
Two numbers in that table restructure the whole problem. Survival water (drinking and cooking) is 11 L/day, or about 2% of the pipe's daily delivery. Functioning water (add sanitation and basic hygiene at emergency rations) is roughly 40 L/day. Everything else is comfort riding on the same single point of failure and inflating our sense of what an emergency requires.
The dependency chain above that pipe: one municipal utility, one treatment plant serving this district, electric pumps with a finite backup window, and 11 km of mains with a real (if low) contamination-event rate. Probability of a multi-day interruption in any year: low single digits, by published utility data for systems this size. Blast radius: total. That combination (low probability, total blast radius) is exactly the shape of risk people systematically underinsure, because the annualized expected loss feels small right up until the year it is not.
The remediation, priced
The fix took one weekend and $412, and the design principle was the same as ever: buffer first, production second, and match the redundancy to the actual requirement, not the comfort number.
Stored water: 14 days at functioning rations. Two 208 L food-grade drums plus rotation of supermarket bottles for drinking. Cost: $148. The drums live where the freeze line and the house's dead weight allow, they get treated and rotated on a 12-month calendar reminder, and together with the water heater's 189 L (a free tank most people forget they own; know your drain valve) the household holds 605 L, which is 15.1 days at 40 L/day.
Treatment: the multiplier. A gravity-fed ceramic filter rated for 5,000 L plus chemical backup. Cost: $189. Storage answers "how long." Treatment answers "then what," because it converts the rain barrels, the neighbor's pool, and the creek 400 m away from scenery into supply. A filter is decentralized infrastructure in its purest form: it makes water sources fungible.
Rain capture: measured, not romanticized. The existing garden barrels total 420 L and my roof sheds about 55 L per millimeter of rain. In this climate that is meaningful in spring and a dusty joke in August, so it is logged as opportunistic supply only. People who plan on rain are planning on weather.
What I declined to buy
A well: quotes came in at $8,400 to $12,000 for this geology, against a hazard with a low single-digit annual probability. Fails the 10% rule from the redundancy ledger by an order of magnitude. A whole-house reverse osmosis system: solves a quality problem I measured myself out of (my tap water tests fine; $34 of lab work beats $2,000 of anxiety plumbing). The discipline cuts both ways or it is not discipline.
The lesson the omission taught
My audit missed water because reliability had made it invisible, and the systems most likely to be missing from your dependency list are precisely the ones that have worked too well to think about. The corrective heuristic, now part of my quarterly review: walk the utilities into the house physically (every pipe, every wire, every line crossing the property boundary) and demand each one justify its absence from the risk register.
Fourteen days of buffer, 5,000 L of treatment capacity, $412, one weekend. Confidence that this is the highest resilience-per-dollar line item in the entire household program: 0.90. It embarrasses the solar battery, and the solar battery knows it.