A rain collector crate holds 400 units of liquid and needs carpentry level 3 to build; a rain collector barrel holds 600 units and needs carpentry level 5. Both come in two material variants — garbage bags or a tarp — that change the recipe’s plumbing-adjacent ingredient but not the capacity or skill requirement. If you plumb a sink to more than one collector, the numbers above do not simply add up in the way you would expect from the UI: the sink reads and drains one collector at a time and will not switch to the next until the active one hits zero, so a full backup barrel next to a nearly empty one still shows the low number and can fail a task that needs more water than the active barrel has left. This is a community-documented behavior, not something stated on pzwiki’s own Plumbing page, and it changes how much a given collector count is actually worth in practice.
Capacity by collector type, current build
Both variants of each type share the same capacity, so the choice between garbage bags and tarp is about which material you have on hand, not storage size.
| Collectors | Crate total (400/each) | Barrel total (600/each) |
|---|---|---|
| 1 | 400 units | 600 units |
| 2 | 800 units | 1,200 units |
| 4 | 1,600 units | 2,400 units |
| 8 | 3,200 units | 4,800 units |
Build requirements, side by side
| Property | Rain Collector Crate | Rain Collector Barrel |
|---|---|---|
| Liquid capacity | 400 units | 600 units |
| Carpentry level to build | 3 | 5 |
| Recipe (garbage bags variant) | Plank ×4, Nails ×4, garbage bag (tag) ×4, hammer (tag) ×1 | Plank ×6, Nails ×5, garbage bag (tag) ×4, hammer (tag) ×1 |
| Recipe (tarp variant) | Plank ×4, Nails ×4, Tarp ×1, hammer (tag) ×1 | Plank ×6, Nails ×5, Tarp ×1, hammer (tag) ×1 |
| Carpentry XP on build | 30 | 50 |
| Has a lid | No | Yes |
The barrel’s lid is the other practical difference beyond capacity: pzwiki states the crate “does not have a lid,” while the barrel’s can be opened and closed from the right-click context menu — relevant mainly for keeping debris or rain-diluted contamination out when it is not actively raining, since both types collect tainted water either way that needs boiling before drinking.
Why “how many days will this last” needs your own number, not ours
pzwiki does not publish a per-survivor daily water requirement in units or liters — the Thirst page describes dehydration as a percentage-based moodle rate, not a liquid quantity, so converting that into “units per person per day” would mean inventing a conversion this page cannot source. The practical way to plan buffer days is to track your own household’s draw directly: note a collector’s displayed liquid level, use normally for one full in-game day, and check the level again. That difference, multiplied by the number of people drawing from the same setup, is your real daily draw — and it will vary with how much washing and cooking your base does, which pzwiki does not model as a fixed number either.
Once you have that number, dividing the capacity totals in the table above by it gives days of buffer per collector count. A base running two barrels (1,200 units total) against a draw of 100 units/day gets 12 days; the same two barrels against 50 units/day get 24. Both are arithmetic on your own tracked number, not a claim this page is making about what a typical household uses.
The plumbing catch: multiple collectors do not pool
pzwiki’s Plumbing page confirms the mechanics that make multiple collectors possible at all: a water fixture “can draw from multiple reservoirs with valid placement,” reservoirs must sit one floor above the fixture within a 3x3 area, and reservoirs can be freely added or removed from that zone without breaking the plumbing connection once it is established. What the page does not describe is how the fixture chooses between reservoirs when more than one is connected.
A June 2026 community thread on r/projectzomboid (Build 42) worked that part out through testing: one commenter summarized it as “whenever one barrel is depleted, the consumer… automatically switches to other barrel which contains water,” and another added the operational catch — “you have to fully use one before it switches to another, meaning you can’t do things that require more water than what’s in one of the collectors.” The first commenter also noted the one exception to smooth switching: the washing machine, “since it takes 100units/wash” — and the thread’s explanation is that a load will not start unless the active collector can supply all of that in one go. None of this is confirmed on an official pzwiki mechanics page as of the version checked below — it is player testing, cited here as such, not a developer statement.
What this means for placement
- Displayed water level on a plumbed sink reflects one collector, not your total. Do not use the sink’s readout to judge how much water your base actually has left; check the collectors directly.
- Large single draws (a full washing machine load) can fail even with full backup collectors connected, because the game will not combine two partial-to-full reservoirs into one draw.
- If a task fails on a “low water” barrel with full ones next to it, manually draining the low one (by hand, or with a bucket) is the reported workaround to force the switch early rather than waiting for natural use to empty it.
Related reading
Rain collectors only matter if the base has outdoor space to put them in the first place — the outdoor-space criterion in the base location scorecard covers why that has to be checked before anything else. And the carpentry levels above are one entry in a longer list of skill gates that block recipes outright — the crafting-requirement diagnostic is the general version of “why can’t I build this yet.”
Sources
- PZwiki, Rain Collector Barrel (Garbage Bags) — read in full 17 September 2026. 600-unit capacity, carpentry level 5, the lid feature, and the garbage-bags recipe (Plank ×6, Nails ×5, garbage bag (tag) ×4, hammer ×1, Carpentry XP 50). Page stamped 42.12.3; page banner states current stable is 42.20.4
- PZwiki, Rain Collector Barrel (Tarp) — read in full 17 September 2026. Same 600-unit capacity and carpentry level 5; tarp recipe (Plank ×6, Nails ×5, Tarp ×1, hammer ×1). Page stamped 42.12.3
- PZwiki, Rain Collector Crate (Garbage Bags) — read in full 17 September 2026. 400-unit capacity, carpentry level 3, no lid, garbage-bags recipe (Plank ×4, Nails ×4, garbage bag (tag) ×4, hammer ×1, Carpentry XP 30). Page stamped 42.12.3
- PZwiki, Rain Collector Crate (Tarp) — read in full 17 September 2026. Same 400-unit capacity and carpentry level 3; tarp recipe (Plank ×4, Nails ×4, Tarp ×1, hammer ×1). Page stamped 42.12.3
- PZwiki, Plumbing — read in full 17 September 2026. Multi-reservoir draw eligibility, the one-floor/3x3 placement rule, and reservoirs being addable/removable without breaking an established connection. Page notes the system is “somewhat obscure, and likely incomplete.”
- Reddit, r/projectzomboid: “Multiple water collectors not linking up above my sink (B42)” — read in full 17 September 2026, thread dated June 2026. Community-tested description of sequential (not pooled) draw between connected reservoirs, and the washing-machine failure case; cited as player testing, not an official source.
- Steam news, Project Zomboid news hub — checked 17 September 2026. Confirms 42.20.4 STABLE (26 August 2026 hotfix) as the most recent stable release, with no newer stable patch listed since.
