Inside TYPO3

3.8.2. Character sets

Currently, local charsets are used by default inside TYPO3. However it is highly recommended to set $TYPO3_CONF_VARS['BE']['forceCharset'] = "utf-8" which will force the backend to run in utf-8 regardless of "native" charset. Forcing the charset to "utf-8" also means that all content in the database will be managed in "utf-8" and you might corrupt existing data if you set it after having added content in another charset.