Build 42 Water and Power Shutoff — When It Happens and How to Outlast It

The shutoff is Project Zomboid's oldest clock, and Build 42 changed it twice over: the fluid system rewired how water and fuel behave once utilities die, and the sandbox menu now exposes shutoff settings in a confusing way (more below). This guide covers when the lights go out and the four prep pillars — water, power, lighting, food — on 42.20. Checked 2026-08-04. Pair with our first-week guide.

When do water and power shut off?

It's a sandbox setting, and the two utilities roll separately. Verified defaults per scenario (PZwiki's Custom Sandbox page):

Full option list runs Instant, 0–30 days, 0–2 months, 2–6 months, 0–6 months, 6–12 months, 0–1 year, 0–5 years. Note that the community's often-quoted "7–30 days, usually day 14" window doesn't match the wiki's wording — treat it as unverified.

The warning systems differ too (PZwiki's Metagame page):

• Electricity: announced by the Automated Emergency Broadcast System (AEBS) on the radio up to two days before, and a sound plays across Knox Country at the moment of shutoff. Keep a radio.
• Water: not announced — the only signs are dwindling remaining water (right-click sinks) and gurgling air-mixed water from taps.

Practical read for Apocalypse: plan as if water dies any day in the first month and power follows by day 30 — bank water from day one, and treat the AEBS broadcast as your final generator deadline. (Custom sandbox shows the shutoff controls twice — a range dropdown plus a numeric input; a known UI quirk since early 42.0 builds.)

What stops working when the grid dies

• Taps stop delivering water, and everything grid-powered dies: fridges, freezers, stoves, lights, TVs, washers.
• Generators take over per-building: a connected unit powers every device in its 20-tile radius cylinder — fuel math in our generator guide.
• Gas station pumps die unless you power them with a generator (and have the exterior-generator sandbox option on), which is why fuel logistics tighten at the same moment your lights go out.

Pillar 1: water banking

While the taps still run, bank water aggressively. The Knox Event starts in July, so heat and thirst pressure arrive fast.

• Fill every container before the taps die. Verified capacities: bucket 10 L, dispenser bottle 15 L, backpack sprayer 16 L, watering can 8 L, plastic bottle 2/1 L, pot and kettle 1.5 L, saucepan 0.6 L, mug 0.2 L — containers above 3 L can't be drunk from directly, so keep small bottles for the field.
• Water left in pipes and basins after shutoff never spoils — ration what's already sitting in sinks and bathtubs before touching your stockpile.
• Build rain collector barrels (Carpentry 5, tarp variant, 600 L capacity; a garbage-bags variant exists). Barrels collect tainted water that must be boiled — but a barrel plumbed into a sink supplies drinkable water without purification (community-reported plumbing rule: reservoir one floor above the sink, within a 3×3 area).
• Water dispensers found around Knox Country give fresh drinking water while they last — a bridge, not a plan.
• Boiling makes tainted water safe and is faster in B42; empty cans can serve as boiling vessels. Purification tablets clean limited amounts of tainted water.

Rule of thumb from prep practice: a week of drinking-plus-cooking water per character before you trust your rain barrels, and at least two barrels per base.

Pillar 2: power

Your post-grid options, in order of effort:

1. Generator — the only way to keep appliances running. Requires Electrical 3, the Electrician/Engineer occupation, or the How to Use Generators magazine to connect. Budget fuel: a fridge draws 0.008 L/h, so a 10 L tank keeps a light household load running for weeks. See the generator guide for variant noise and durability.
2. Batteries and propane — batteries (destroyed when drained), car batteries with a charger, and propane tanks are the wiki's listed small-power options: flashlights, radios, lantern-style light. No solar panels exist in vanilla — that's mod territory.
3. No power at all — a valid strategy if you commit to fire-based cooking, natural light discipline, and preserved food. Many veteran Apocalypse runs skip generators for the first winter entirely to avoid the noise radius.

Pillar 3: lighting

Prep habit: one flashlight plus spare batteries per character, candles stockpiled from every looted house, and a lit safe room reachable without opening doors.

Pillar 4: food without a fridge

The fridge is the first casualty. Your route out, in order:

1. Cook down perishables immediately — soups and stews stretch ingredients and use fire instead of grid power. Full mechanics in our cooking guide.
2. Jar and preserve surpluses — jarring needs vegetables ×6 + jar + lid and the canning path; it's the flagship power-free preservation route in B42.
3. Build drying racks — B42's dedicated food-preservation furniture for harvest surpluses.
4. Keep a generator on the fridge only if your fuel income beats the draw — otherwise the fuel is better spent on trips. Fishing stays productive all year and partially replaces cold storage with fresh catch (fishing guide).

Pre-shutoff checklist

• All containers filled; clean/dirty water shelves separated
• Rain barrels placed and empty
• Generator located, tested, fueled (10 L minimum) — or consciously skipped
• How to Use Generators magazine or Electrical 3 secured
• Flashlights, batteries, candles stocked
• Perishables cooked down; jars, lids, and drying rack materials gathered
• Fuel cans (20 L jerry cans) topped up and sealed before evaporation and dead pumps bite

Verified on 42.20 · Last checked 2026-08-04

Scenario defaults, the option list, AEBS electricity warnings, and the unannounced water shutoff come from PZwiki's Custom Sandbox and Metagame pages; container capacities and rain barrel specs from the Fluid container and Rain Collector Barrel pages. Generator rules from PZwiki's Generator page (42.13.1 stamp); hose siphoning and 20 L jerry cans are community-reported via the veterans' guide (gasoline evaporation isn't wiki-documented). Re-check windows after patches — sandbox defaults have moved before.