Fallout 4 Settlement Guide — Building a Water Empire for Caps

Settlements look like a role-playing hobby but function as the game's best economic engine, and the core of it is water. Building industrial water purifiers produces purified water that is deposited into the settlement's workbench over time, and purified water sells to any vendor for a solid price while weighing almost nothing. Set up a few purifiers at a settlement with a large body of water — Sanctuary is the natural choice because of the river — and you have a passive income stream that requires no combat and no risk.

The infrastructure that makes this work is a supply line network. The Local Leader perk unlocks caravan routes between settlements, which shares crafting materials and food across all of them, so you only need one settlement producing food and one producing water. Keep each settlement's population happy with beds, food and defence, because unhappy settlements stop producing at full rate — a few turrets solve most defence problems permanently and cost almost nothing.

Your best companion for this is a strong Charisma stat, which raises the prices you get when selling and lowers what you pay when buying. Combine high Charisma with a shop built at one settlement and you can convert purified water into caps, then caps into the weapons and power armour you actually want. It is not the most exciting way to play Fallout 4, but it turns the Commonwealth's economy from a constant struggle into a solved problem.