There currently isn't an official Web3 type definition included in the DefinitelyTyped project. Until that happens, we will continue to improve our own type definition. If it get's close to comprehensive, we'll add it to DefinitelyTyped.
Using npm:
npm install --save-dev web3-typescript-typings
Using yarn:
yarn add web3-typescript-typings -D
Also don't forget to manually include index.d.ts within an include section of your tsconfig.json
"include": [
...
"./node_modules/web3-typescript-typings/index.d.ts"
]
And you're ready to go to a bright type-safe and distributed future!